Version: 2.5.x (dev)

Source / Track processing

`append`

Append an extra track to every track. Set the metadata ‘liq_append’ to false to inhibit appending on one track.

Type:

(?id : string?, ?insert_missing : bool, ?merge : bool, source('a),
 (([string * string]) -> source('a))) -> source('a)
where 'a is an orderable type

Composition:

This source inherits composition from its effective source.

Arguments:

id (of type string?, which defaults to "append")
insert_missing (of type bool, which defaults to true): Treat track beginnings without metadata as having empty one.
merge (of type bool, which defaults to false): Merge the track with its appended track.
(unlabeled) (of type source('a) where 'a is an orderable type): Given the metadata, build the source producing the track to append. The function can return null to prevent appending a new track.
(unlabeled) (of type ([string * string]) -> source('a) where 'a is an orderable type)

Methods:

buffered (of type () -> [string * float]): Length of buffered data.
cancel_pending (of type () -> unit):
clear_last_metadata (of type () -> unit): Clear the last metadata from the source.
clock (of type clock): The source's clock
duration (of type () -> float): Estimation of the duration of the current track.
elapsed (of type () -> float): Elapsed time in the current track.
fallible (of type bool): Indicate if a source may fail, i.e. may not be ready to stream.
generate_frame (of type () -> unit): Generate a frame from the source without consuming it. This can be useful in advanced cases where generating a frame is required to trigger some side effect like calculating some metadata before making a decision. You should make sure that the source is available before calling this function and it should only be called inside synchronous streaming loop callback such as on_frame!
id (of type () -> string): Identifier of the source.
insert_metadata (of type (?override : bool, ?new_track : bool, [string * string]) -> unit): Dynamically insert metadata in a stream. Inserts a new track with the given metadata if new_track is true. When override is false, metadata that the source provides itself takes precedence over the inserted one.
is_active (of type () -> bool): true if the source is active, i.e. it is continuously animated by its own clock whenever it is ready. Typically, true for outputs and sources such as input.http.
is_ready (of type () -> bool): Indicate if a source is ready to stream. This does not mean that the source is currently streaming, just that its resources are all properly initialized.
is_up (of type () -> bool): Indicate that the source can be asked to produce some data at any time. This is true when the source is currently being used or if it could be used at any time, typically inside a switch or fallback.
last_metadata (of type () -> [string * string]?): Return the last metadata from the source.
log (of type {level : (() -> int).{set : (int) -> unit}}): Get or set the source's log level, from 1 to 5.
pending (of type () -> source('A)? where 'A is an orderable type):
register_command (of type (?usage : string?, description : string, string, ((string) -> string)) -> unit): Register a server command for this source. Command is registered under the source's id namespace when it gets up and de-registered when it gets down.
remaining (of type () -> float): Estimation of remaining time in the current track.
reset_last_metadata_on_track (of type (() -> bool).{set : (bool) -> unit}): If true, the source's last_metadata is reset on each new track. If a metadata is present along with the track mark, then it becomes the new last_metadata, otherwise, last_metadata becomes null`.
seek (of type (float) -> float): Seek forward, in seconds (returns the amount of time effectively seeked).
selected (of type () -> source('A)? where 'A is an orderable type): Currently selected source.
self_sync (of type () -> bool): Is the source currently controlling its own real-time loop.
self_sync_description (of type () -> string):
set_pending (of type (source('A)?) -> unit where 'A is an orderable type):
skip (of type (?cancel_pending : bool) -> unit):
time (of type () -> float): Get a source's time, based on its assigned clock.

Callbacks:

on_collect (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source is collected
on_frame (of type (?before : bool, synchronous : bool, (() -> unit)) -> unit): Call a given handler on frame. When before is true, callback is executed before computing the frame and after otherwise
on_frame_checksum (of type (?before : ((string?) -> unit)?, synchronous : bool, ((cache : string?, string) -> unit)) -> unit): Call a given handler Register callbacks to compute frame checksums for debugging purposes. This is useful to track frame content changes through the streaming pipeline. The before callback is called before computing the frame with the checksum of the cached frame (if any, null otherwise). The main callback is called after computing the frame with the checksum of the generated frame and the remaining cache (if any).
on_metadata (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler to execute on each metadata
on_position (of type (position : {float}, ?remaining : bool, ?allow_partial : bool, synchronous : bool, ((float, [string * string]) -> unit)) -> unit): Call a given handler on track position. If remaining is false, callback is executed when position in track is more or equal to position. If remaining is true, callback is executed when remaining time in the current track is less or equal to position. Keep in mind that elapsed time is exact while remaining time is always estimated. Remaining time is usually more accurate for file-based sources. When allow_partial is true, if the current track ends before the offset position is reached, callback is still executed
on_shutdown (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source shuts down
on_track (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler on track marks
on_wake_up (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called after the source is asked to get ready

Composition methods:

composition_type (of type (() -> string).{set : (string) -> unit}): This source inherits composition from its effective source.
on_leave (of type ({source : source('A), track_sensitive : bool}) -> unit where 'A is an orderable type): Called after switching away from this source in a switch operator, once the transition using the ending source has completed. Receives a record with source (the source being left) and track_sensitive (true if the ending source's last frame had a track mark, i.e. it finished naturally; false if it was preempted mid-track). This function must return quickly as it runs in the streaming thread. The default depends on the active composition profile: file sources (source.composition.file) skip the source when preempted mid-track so it starts fresh on its next selection, and do nothing when it finished naturally; live sources (source.composition.live) do nothing.
on_select (of type ({ending : source('A)?, replay_metadata : bool, starting : source('A)}) -> source('A) where 'A is an orderable type): Called when selecting this source in a switch operator. Receives a record with starting (the incoming source) and ending (the previous source, or null when the ending source reached a track boundary). Returns the source to use. By default, both file and live profiles fade out ending when non-null (up to 1 second). The default is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
replay_metadata (of type {bool}): Whether to replay the latest metadata on this source when it is selected in a switch operator. Defaults to true. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
single (of type bool): Forbid the selection of this source for two consecutive tracks in switch operators. Defaults to false.
track_sensitive (of type {bool}): Whether this source insists on track boundaries in switch operators: when true, it prefers not to be interrupted mid-track and not to be started mid-track. A switch may only cut into a track that is still playing when at least one of the two sources involved has track_sensitive set to false; otherwise it waits for the playing source to reach a track boundary. File-based sources default to true; live network and hardware inputs default to false. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).

`autocue.plot`

Plot two sine tracks with given autocue params. Used for visualizing and testing autocue crossfade transitions.

Type:

(?png : string?, ?dir : string?, ?font : 'a?, ?font_size : int,
 old_autocue : 'h
 .{
   amplify? : 'c,
   cue_in : float,
   cue_out : float,
   extra_metadata? : [string * string],
   fade_in : 'b,
   fade_in_curve? : 'e,
   fade_in_type? : 'd,
   fade_out : float,
   fade_out_curve? : 'g,
   fade_out_type? : 'f,
   start_next? : float
 }, new_autocue : 'o
 .{
   amplify? : 'j,
   cue_in : float,
   cue_out : float,
   extra_metadata? : [string * string],
   fade_in : 'i,
   fade_in_curve? : 'l,
   fade_in_type? : 'k,
   fade_out : float,
   fade_out_curve? : 'n,
   fade_out_type? : 'm,
   start_next? : float
 }, ?sync : string, on_stop : (() -> 'p)) -> unit

Arguments:

png (of type string?, which defaults to null)
dir (of type string?, which defaults to null)
font (of type 'a?, which defaults to null)
font_size (of type int, which defaults to 10)
old_autocue (of type 'h .{ amplify? : 'c, cue_in : float, cue_out : float, extra_metadata? : [string * string], fade_in : 'b, fade_in_curve? : 'e, fade_in_type? : 'd, fade_out : float, fade_out_curve? : 'g, fade_out_type? : 'f, start_next? : float })
new_autocue (of type 'o .{ amplify? : 'j, cue_in : float, cue_out : float, extra_metadata? : [string * string], fade_in : 'i, fade_in_curve? : 'l, fade_in_type? : 'k, fade_out : float, fade_out_curve? : 'n, fade_out_type? : 'm, start_next? : float })
sync (of type string, which defaults to "auto")
on_stop (of type () -> 'p)

`chop`

Regularly insert track boundaries in a stream (useful for testing tracks).

Type:

(?every : {float}, ?metadata : {[string * string]}, source('a)) -> source('a)

Arguments:

every (of type {float}, which defaults to 3.0): Duration of a track (in seconds).
metadata (of type {[string * string]}, which defaults to []): Metadata for tracks.
(unlabeled) (of type source('a)): The stream.

Methods:

buffered (of type () -> [string * float]): Length of buffered data.
clear_last_metadata (of type () -> unit): Clear the last metadata from the source.
clock (of type clock): The source's clock
duration (of type () -> float): Estimation of the duration of the current track.
elapsed (of type () -> float): Elapsed time in the current track.
fallible (of type bool): Indicate if a source may fail, i.e. may not be ready to stream.
generate_frame (of type () -> unit): Generate a frame from the source without consuming it. This can be useful in advanced cases where generating a frame is required to trigger some side effect like calculating some metadata before making a decision. You should make sure that the source is available before calling this function and it should only be called inside synchronous streaming loop callback such as on_frame!
id (of type () -> string): Identifier of the source.
insert_metadata (of type (?override : bool, ?new_track : bool, [string * string]) -> unit): Dynamically insert metadata in a stream. Inserts a new track with the given metadata if new_track is true. When override is false, metadata that the source provides itself takes precedence over the inserted one.
is_active (of type () -> bool): true if the source is active, i.e. it is continuously animated by its own clock whenever it is ready. Typically, true for outputs and sources such as input.http.
is_ready (of type () -> bool): Indicate if a source is ready to stream. This does not mean that the source is currently streaming, just that its resources are all properly initialized.
is_up (of type () -> bool): Indicate that the source can be asked to produce some data at any time. This is true when the source is currently being used or if it could be used at any time, typically inside a switch or fallback.
last_metadata (of type () -> [string * string]?): Return the last metadata from the source.
log (of type {level : (() -> int).{set : (int) -> unit}}): Get or set the source's log level, from 1 to 5.
register_command (of type (?usage : string?, description : string, string, ((string) -> string)) -> unit): Register a server command for this source. Command is registered under the source's id namespace when it gets up and de-registered when it gets down.
remaining (of type () -> float): Estimation of remaining time in the current track.
reset_last_metadata_on_track (of type (() -> bool).{set : (bool) -> unit}): If true, the source's last_metadata is reset on each new track. If a metadata is present along with the track mark, then it becomes the new last_metadata, otherwise, last_metadata becomes null`.
seek (of type (float) -> float): Seek forward, in seconds (returns the amount of time effectively seeked).
self_sync (of type () -> bool): Is the source currently controlling its own real-time loop.
self_sync_description (of type () -> string):
skip (of type () -> unit): Skip to the next track.
time (of type () -> float): Get a source's time, based on its assigned clock.

Callbacks:

on_collect (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source is collected
on_frame (of type (?before : bool, synchronous : bool, (() -> unit)) -> unit): Call a given handler on frame. When before is true, callback is executed before computing the frame and after otherwise
on_frame_checksum (of type (?before : ((string?) -> unit)?, synchronous : bool, ((cache : string?, string) -> unit)) -> unit): Call a given handler Register callbacks to compute frame checksums for debugging purposes. This is useful to track frame content changes through the streaming pipeline. The before callback is called before computing the frame with the checksum of the cached frame (if any, null otherwise). The main callback is called after computing the frame with the checksum of the generated frame and the remaining cache (if any).
on_metadata (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler to execute on each metadata
on_position (of type (position : {float}, ?remaining : bool, ?allow_partial : bool, synchronous : bool, ((float, [string * string]) -> unit)) -> unit): Call a given handler on track position. If remaining is false, callback is executed when position in track is more or equal to position. If remaining is true, callback is executed when remaining time in the current track is less or equal to position. Keep in mind that elapsed time is exact while remaining time is always estimated. Remaining time is usually more accurate for file-based sources. When allow_partial is true, if the current track ends before the offset position is reached, callback is still executed
on_shutdown (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source shuts down
on_track (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler on track marks
on_wake_up (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called after the source is asked to get ready

Composition methods:

on_leave (of type ({source : source('A), track_sensitive : bool}) -> unit): Called after switching away from this source in a switch operator, once the transition using the ending source has completed. Receives a record with source (the source being left) and track_sensitive (true if the ending source's last frame had a track mark, i.e. it finished naturally; false if it was preempted mid-track). This function must return quickly as it runs in the streaming thread. The default depends on the active composition profile: file sources (source.composition.file) skip the source when preempted mid-track so it starts fresh on its next selection, and do nothing when it finished naturally; live sources (source.composition.live) do nothing.
on_select (of type ({ending : source('A)?, replay_metadata : bool, starting : source('A)}) -> source('A)): Called when selecting this source in a switch operator. Receives a record with starting (the incoming source) and ending (the previous source, or null when the ending source reached a track boundary). Returns the source to use. By default, both file and live profiles fade out ending when non-null (up to 1 second). The default is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
replay_metadata (of type {bool}): Whether to replay the latest metadata on this source when it is selected in a switch operator. Defaults to true. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
single (of type bool): Forbid the selection of this source for two consecutive tracks in switch operators. Defaults to false.
track_sensitive (of type {bool}): Whether this source insists on track boundaries in switch operators: when true, it prefers not to be interrupted mid-track and not to be started mid-track. A switch may only cut into a track that is still playing when at least one of the two sources involved has track_sensitive set to false; otherwise it waits for the playing source to reach a track boundary. File-based sources default to true; live network and hardware inputs default to false. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).

`cross.plot`

Plot the first crossfade transition. Used for visualizing and testing crossfade transitions.

Type:

(?png : string?, ?dir : string?, ?font : 'a?, ?font_size : int,
 source(audio=pcm('b), 'c)) -> source(audio=pcm('b), 'c)
where
  'c is a set of tracks to be muxed into a source and a set of internal tracks and an orderable type

Composition:

This source uses file composition by default.

Arguments:

png (of type string?, which defaults to null)
dir (of type string?, which defaults to null)
font (of type 'a?, which defaults to null)
font_size (of type int, which defaults to 10)
(unlabeled) (of type source(audio=pcm('b), 'c) where 'c is a set of tracks to be muxed into a source and a set of internal tracks and an orderable type)

Methods:

buffered (of type () -> [string * float]):
clear_last_metadata (of type () -> unit): Clear the last metadata from the source.
clock (of type clock): The source's clock
cross_duration (of type () -> float):
duration (of type () -> float):
elapsed (of type () -> float): Elapsed time in the current track.
fallible (of type bool): Indicate if a source may fail, i.e. may not be ready to stream.
generate_frame (of type () -> unit): Generate a frame from the source without consuming it. This can be useful in advanced cases where generating a frame is required to trigger some side effect like calculating some metadata before making a decision. You should make sure that the source is available before calling this function and it should only be called inside synchronous streaming loop callback such as on_frame!
id (of type () -> string): Identifier of the source.
insert_metadata (of type (?override : bool, ?new_track : bool, [string * string]) -> unit): Dynamically insert metadata in a stream. Inserts a new track with the given metadata if new_track is true. When override is false, metadata that the source provides itself takes precedence over the inserted one.
is_active (of type () -> bool): true if the source is active, i.e. it is continuously animated by its own clock whenever it is ready. Typically, true for outputs and sources such as input.http.
is_ready (of type () -> bool): Indicate if a source is ready to stream. This does not mean that the source is currently streaming, just that its resources are all properly initialized.
is_up (of type () -> bool): Indicate that the source can be asked to produce some data at any time. This is true when the source is currently being used or if it could be used at any time, typically inside a switch or fallback.
last_metadata (of type () -> [string * string]?): Return the last metadata from the source.
log (of type {level : (() -> int).{set : (int) -> unit}}): Get or set the source's log level, from 1 to 5.
register_command (of type (?usage : string?, description : string, string, ((string) -> string)) -> unit): Register a server command for this source. Command is registered under the source's id namespace when it gets up and de-registered when it gets down.
remaining (of type () -> float): Estimation of remaining time in the current track.
reset_last_metadata_on_track (of type (() -> bool).{set : (bool) -> unit}): If true, the source's last_metadata is reset on each new track. If a metadata is present along with the track mark, then it becomes the new last_metadata, otherwise, last_metadata becomes null`.
seek (of type (float) -> float): Seek forward, in seconds (returns the amount of time effectively seeked).
self_sync (of type () -> bool): Is the source currently controlling its own real-time loop.
self_sync_description (of type () -> string):
skip (of type () -> unit): Skip to the next track.
time (of type () -> float): Get a source's time, based on its assigned clock.

Callbacks:

on_collect (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source is collected
on_frame (of type (?before : bool, synchronous : bool, (() -> unit)) -> unit): Call a given handler on frame. When before is true, callback is executed before computing the frame and after otherwise
on_frame_checksum (of type (?before : ((string?) -> unit)?, synchronous : bool, ((cache : string?, string) -> unit)) -> unit): Call a given handler Register callbacks to compute frame checksums for debugging purposes. This is useful to track frame content changes through the streaming pipeline. The before callback is called before computing the frame with the checksum of the cached frame (if any, null otherwise). The main callback is called after computing the frame with the checksum of the generated frame and the remaining cache (if any).
on_metadata (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler to execute on each metadata
on_position (of type (position : {float}, ?remaining : bool, ?allow_partial : bool, synchronous : bool, ((float, [string * string]) -> unit)) -> unit): Call a given handler on track position. If remaining is false, callback is executed when position in track is more or equal to position. If remaining is true, callback is executed when remaining time in the current track is less or equal to position. Keep in mind that elapsed time is exact while remaining time is always estimated. Remaining time is usually more accurate for file-based sources. When allow_partial is true, if the current track ends before the offset position is reached, callback is still executed
on_shutdown (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source shuts down
on_track (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler on track marks
on_wake_up (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called after the source is asked to get ready

Composition methods:

composition_type (of type (() -> string).{set : (string) -> unit}): This source uses file composition by default.
on_leave (of type ({source : source(audio=pcm('B), 'A), track_sensitive : bool}) -> unit where 'A is a set of tracks to be muxed into a source and a set of internal tracks and an orderable type): Called after switching away from this source in a switch operator, once the transition using the ending source has completed. Receives a record with source (the source being left) and track_sensitive (true if the ending source's last frame had a track mark, i.e. it finished naturally; false if it was preempted mid-track). This function must return quickly as it runs in the streaming thread. The default depends on the active composition profile: file sources (source.composition.file) skip the source when preempted mid-track so it starts fresh on its next selection, and do nothing when it finished naturally; live sources (source.composition.live) do nothing.
on_select (of type ( { ending : source(audio=pcm('B), 'A)?, replay_metadata : bool, starting : source(audio=pcm('B), 'A) }) -> source(audio=pcm('B), 'A) where 'A is a set of tracks to be muxed into a source and a set of internal tracks and an orderable type): Called when selecting this source in a switch operator. Receives a record with starting (the incoming source) and ending (the previous source, or null when the ending source reached a track boundary). Returns the source to use. By default, both file and live profiles fade out ending when non-null (up to 1 second). The default is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
replay_metadata (of type {bool}): Whether to replay the latest metadata on this source when it is selected in a switch operator. Defaults to true. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
single (of type bool): Forbid the selection of this source for two consecutive tracks in switch operators. Defaults to false.
track_sensitive (of type {bool}): Whether this source insists on track boundaries in switch operators: when true, it prefers not to be interrupted mid-track and not to be started mid-track. A switch may only cut into a track that is still playing when at least one of the two sources involved has track_sensitive set to false; otherwise it waits for the playing source to reach a track boundary. File-based sources default to true; live network and hardware inputs default to false. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).

`fallback.skip`

Special track insensitive fallback that always skips current song before switching.

Type:

(source('a), ?fallback : source('a)?) -> source('a)
where 'a is a set of internal tracks

Composition:

This source inherits composition from its effective source.

Arguments:

(unlabeled) (of type source('a) where 'a is a set of internal tracks): The main source.
fallback (of type source('a)? where 'a is a set of internal tracks, which defaults to null): The fallback source. Defaults to blank if null.

Methods:

buffered (of type () -> [string * float]): Length of buffered data.
clear_last_metadata (of type () -> unit): Clear the last metadata from the source.
clock (of type clock): The source's clock
duration (of type () -> float): Estimation of the duration of the current track.
elapsed (of type () -> float): Elapsed time in the current track.
fallible (of type bool): Indicate if a source may fail, i.e. may not be ready to stream.
generate_frame (of type () -> unit): Generate a frame from the source without consuming it. This can be useful in advanced cases where generating a frame is required to trigger some side effect like calculating some metadata before making a decision. You should make sure that the source is available before calling this function and it should only be called inside synchronous streaming loop callback such as on_frame!
id (of type () -> string): Identifier of the source.
insert_metadata (of type (?override : bool, ?new_track : bool, [string * string]) -> unit): Dynamically insert metadata in a stream. Inserts a new track with the given metadata if new_track is true. When override is false, metadata that the source provides itself takes precedence over the inserted one.
is_active (of type () -> bool): true if the source is active, i.e. it is continuously animated by its own clock whenever it is ready. Typically, true for outputs and sources such as input.http.
is_ready (of type () -> bool): Indicate if a source is ready to stream. This does not mean that the source is currently streaming, just that its resources are all properly initialized.
is_up (of type () -> bool): Indicate that the source can be asked to produce some data at any time. This is true when the source is currently being used or if it could be used at any time, typically inside a switch or fallback.
last_metadata (of type () -> [string * string]?): Return the last metadata from the source.
log (of type {level : (() -> int).{set : (int) -> unit}}): Get or set the source's log level, from 1 to 5.
register_command (of type (?usage : string?, description : string, string, ((string) -> string)) -> unit): Register a server command for this source. Command is registered under the source's id namespace when it gets up and de-registered when it gets down.
remaining (of type () -> float): Estimation of remaining time in the current track.
reset_last_metadata_on_track (of type (() -> bool).{set : (bool) -> unit}): If true, the source's last_metadata is reset on each new track. If a metadata is present along with the track mark, then it becomes the new last_metadata, otherwise, last_metadata becomes null`.
seek (of type (float) -> float): Seek forward, in seconds (returns the amount of time effectively seeked).
selected (of type () -> source('A)? where 'A is a set of internal tracks): Currently selected source.
self_sync (of type () -> bool): Is the source currently controlling its own real-time loop.
self_sync_description (of type () -> string):
skip (of type () -> unit): Skip to the next track.
time (of type () -> float): Get a source's time, based on its assigned clock.

Callbacks:

on_collect (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source is collected
on_frame (of type (?before : bool, synchronous : bool, (() -> unit)) -> unit): Call a given handler on frame. When before is true, callback is executed before computing the frame and after otherwise
on_frame_checksum (of type (?before : ((string?) -> unit)?, synchronous : bool, ((cache : string?, string) -> unit)) -> unit): Call a given handler Register callbacks to compute frame checksums for debugging purposes. This is useful to track frame content changes through the streaming pipeline. The before callback is called before computing the frame with the checksum of the cached frame (if any, null otherwise). The main callback is called after computing the frame with the checksum of the generated frame and the remaining cache (if any).
on_metadata (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler to execute on each metadata
on_position (of type (position : {float}, ?remaining : bool, ?allow_partial : bool, synchronous : bool, ((float, [string * string]) -> unit)) -> unit): Call a given handler on track position. If remaining is false, callback is executed when position in track is more or equal to position. If remaining is true, callback is executed when remaining time in the current track is less or equal to position. Keep in mind that elapsed time is exact while remaining time is always estimated. Remaining time is usually more accurate for file-based sources. When allow_partial is true, if the current track ends before the offset position is reached, callback is still executed
on_shutdown (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source shuts down
on_track (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler on track marks
on_wake_up (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called after the source is asked to get ready

Composition methods:

composition_type (of type (() -> string).{set : (string) -> unit}): This source inherits composition from its effective source.
on_leave (of type ({source : source('A), track_sensitive : bool}) -> unit where 'A is a set of internal tracks): Called after switching away from this source in a switch operator, once the transition using the ending source has completed. Receives a record with source (the source being left) and track_sensitive (true if the ending source's last frame had a track mark, i.e. it finished naturally; false if it was preempted mid-track). This function must return quickly as it runs in the streaming thread. The default depends on the active composition profile: file sources (source.composition.file) skip the source when preempted mid-track so it starts fresh on its next selection, and do nothing when it finished naturally; live sources (source.composition.live) do nothing.
on_select (of type ({ending : source('A)?, replay_metadata : bool, starting : source('A)}) -> source('A) where 'A is a set of internal tracks): Called when selecting this source in a switch operator. Receives a record with starting (the incoming source) and ending (the previous source, or null when the ending source reached a track boundary). Returns the source to use. By default, both file and live profiles fade out ending when non-null (up to 1 second). The default is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
replay_metadata (of type {bool}): Whether to replay the latest metadata on this source when it is selected in a switch operator. Defaults to true. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
single (of type bool): Forbid the selection of this source for two consecutive tracks in switch operators. Defaults to false.
track_sensitive (of type {bool}): Whether this source insists on track boundaries in switch operators: when true, it prefers not to be interrupted mid-track and not to be started mid-track. A switch may only cut into a track that is still playing when at least one of the two sources involved has track_sensitive set to false; otherwise it waits for the playing source to reach a track boundary. File-based sources default to true; live network and hardware inputs default to false. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).

`map_first_track`

Apply a function to the first track of a source

Type:

(?id : string?, ((source('a)) -> source('a)), source('a)) -> source('a)

Composition:

This source inherits composition from its effective source.

Arguments:

id (of type string?, which defaults to "map_first_track"): Force the value of the source ID.
(unlabeled) (of type (source('a)) -> source('a)): The applied function.
(unlabeled) (of type source('a)): The input source.

Methods:

buffered (of type () -> [string * float]): Length of buffered data.
clear_last_metadata (of type () -> unit): Clear the last metadata from the source.
clock (of type clock): The source's clock
duration (of type () -> float): Estimation of the duration of the current track.
elapsed (of type () -> float): Elapsed time in the current track.
fallible (of type bool): Indicate if a source may fail, i.e. may not be ready to stream.
generate_frame (of type () -> unit): Generate a frame from the source without consuming it. This can be useful in advanced cases where generating a frame is required to trigger some side effect like calculating some metadata before making a decision. You should make sure that the source is available before calling this function and it should only be called inside synchronous streaming loop callback such as on_frame!
id (of type () -> string): Identifier of the source.
insert_metadata (of type (?override : bool, ?new_track : bool, [string * string]) -> unit): Dynamically insert metadata in a stream. Inserts a new track with the given metadata if new_track is true. When override is false, metadata that the source provides itself takes precedence over the inserted one.
is_active (of type () -> bool): true if the source is active, i.e. it is continuously animated by its own clock whenever it is ready. Typically, true for outputs and sources such as input.http.
is_ready (of type () -> bool): Indicate if a source is ready to stream. This does not mean that the source is currently streaming, just that its resources are all properly initialized.
is_up (of type () -> bool): Indicate that the source can be asked to produce some data at any time. This is true when the source is currently being used or if it could be used at any time, typically inside a switch or fallback.
last_metadata (of type () -> [string * string]?): Return the last metadata from the source.
log (of type {level : (() -> int).{set : (int) -> unit}}): Get or set the source's log level, from 1 to 5.
register_command (of type (?usage : string?, description : string, string, ((string) -> string)) -> unit): Register a server command for this source. Command is registered under the source's id namespace when it gets up and de-registered when it gets down.
remaining (of type () -> float): Estimation of remaining time in the current track.
reset_last_metadata_on_track (of type (() -> bool).{set : (bool) -> unit}): If true, the source's last_metadata is reset on each new track. If a metadata is present along with the track mark, then it becomes the new last_metadata, otherwise, last_metadata becomes null`.
seek (of type (float) -> float): Seek forward, in seconds (returns the amount of time effectively seeked).
selected (of type () -> source('A)?): Currently selected source.
self_sync (of type () -> bool): Is the source currently controlling its own real-time loop.
self_sync_description (of type () -> string):
skip (of type () -> unit): Skip to the next track.
time (of type () -> float): Get a source's time, based on its assigned clock.

Callbacks:

on_collect (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source is collected
on_frame (of type (?before : bool, synchronous : bool, (() -> unit)) -> unit): Call a given handler on frame. When before is true, callback is executed before computing the frame and after otherwise
on_frame_checksum (of type (?before : ((string?) -> unit)?, synchronous : bool, ((cache : string?, string) -> unit)) -> unit): Call a given handler Register callbacks to compute frame checksums for debugging purposes. This is useful to track frame content changes through the streaming pipeline. The before callback is called before computing the frame with the checksum of the cached frame (if any, null otherwise). The main callback is called after computing the frame with the checksum of the generated frame and the remaining cache (if any).
on_metadata (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler to execute on each metadata
on_position (of type (position : {float}, ?remaining : bool, ?allow_partial : bool, synchronous : bool, ((float, [string * string]) -> unit)) -> unit): Call a given handler on track position. If remaining is false, callback is executed when position in track is more or equal to position. If remaining is true, callback is executed when remaining time in the current track is less or equal to position. Keep in mind that elapsed time is exact while remaining time is always estimated. Remaining time is usually more accurate for file-based sources. When allow_partial is true, if the current track ends before the offset position is reached, callback is still executed
on_shutdown (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source shuts down
on_track (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler on track marks
on_wake_up (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called after the source is asked to get ready

Composition methods:

composition_type (of type (() -> string).{set : (string) -> unit}): This source inherits composition from its effective source.
on_leave (of type ({source : source('A), track_sensitive : bool}) -> unit): Called after switching away from this source in a switch operator, once the transition using the ending source has completed. Receives a record with source (the source being left) and track_sensitive (true if the ending source's last frame had a track mark, i.e. it finished naturally; false if it was preempted mid-track). This function must return quickly as it runs in the streaming thread. The default depends on the active composition profile: file sources (source.composition.file) skip the source when preempted mid-track so it starts fresh on its next selection, and do nothing when it finished naturally; live sources (source.composition.live) do nothing.
on_select (of type ({ending : source('A)?, replay_metadata : bool, starting : source('A)}) -> source('A)): Called when selecting this source in a switch operator. Receives a record with starting (the incoming source) and ending (the previous source, or null when the ending source reached a track boundary). Returns the source to use. By default, both file and live profiles fade out ending when non-null (up to 1 second). The default is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
replay_metadata (of type {bool}): Whether to replay the latest metadata on this source when it is selected in a switch operator. Defaults to true. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
single (of type bool): Forbid the selection of this source for two consecutive tracks in switch operators. Defaults to false.
track_sensitive (of type {bool}): Whether this source insists on track boundaries in switch operators: when true, it prefers not to be interrupted mid-track and not to be started mid-track. A switch may only cut into a track that is still playing when at least one of the two sources involved has track_sensitive set to false; otherwise it waits for the playing source to reach a track boundary. File-based sources default to true; live network and hardware inputs default to false. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).

`native.fallback`

At the beginning of each track, select the first ready child.

Type:

(?id : string?, ?track_sensitive : bool, {[source('a)]}) -> source('a)

Composition:

This source inherits composition from its effective source.

Arguments:

id (of type string?, which defaults to null): Force the value of the source ID.
track_sensitive (of type bool, which defaults to true): Re-select only on end of tracks.
(unlabeled) (of type {[source('a)]})

Methods:

buffered (of type () -> [string * float]): Length of buffered data.
clear_last_metadata (of type () -> unit): Clear the last metadata from the source.
clock (of type clock): The source's clock
current_source (of type () -> source('A)?): Return the source currently selected.
duration (of type () -> float): Estimation of the duration of the current track.
elapsed (of type () -> float): Elapsed time in the current track.
fallible (of type bool): Indicate if a source may fail, i.e. may not be ready to stream.
generate_frame (of type () -> unit): Generate a frame from the source without consuming it. This can be useful in advanced cases where generating a frame is required to trigger some side effect like calculating some metadata before making a decision. You should make sure that the source is available before calling this function and it should only be called inside synchronous streaming loop callback such as on_frame!
id (of type () -> string): Identifier of the source.
insert_metadata (of type (?override : bool, ?new_track : bool, [string * string]) -> unit): Dynamically insert metadata in a stream. Inserts a new track with the given metadata if new_track is true. When override is false, metadata that the source provides itself takes precedence over the inserted one.
is_active (of type () -> bool): true if the source is active, i.e. it is continuously animated by its own clock whenever it is ready. Typically, true for outputs and sources such as input.http.
is_ready (of type () -> bool): Indicate if a source is ready to stream. This does not mean that the source is currently streaming, just that its resources are all properly initialized.
is_up (of type () -> bool): Indicate that the source can be asked to produce some data at any time. This is true when the source is currently being used or if it could be used at any time, typically inside a switch or fallback.
last_metadata (of type () -> [string * string]?): Return the last metadata from the source.
log (of type {level : (() -> int).{set : (int) -> unit}}): Get or set the source's log level, from 1 to 5.
prepare (of type (source('A)) -> source('A).{activation : activation}): Prepare a source that will be returned later. Returned source has new activation attached to it and should be used to submit to the source later.
register_command (of type (?usage : string?, description : string, string, ((string) -> string)) -> unit): Register a server command for this source. Command is registered under the source's id namespace when it gets up and de-registered when it gets down.
remaining (of type () -> float): Estimation of remaining time in the current track.
reset_last_metadata_on_track (of type (() -> bool).{set : (bool) -> unit}): If true, the source's last_metadata is reset on each new track. If a metadata is present along with the track mark, then it becomes the new last_metadata, otherwise, last_metadata becomes null`.
seek (of type (float) -> float): Seek forward, in seconds (returns the amount of time effectively seeked).
self_sync (of type () -> bool): Is the source currently controlling its own real-time loop.
self_sync_description (of type () -> string):
skip (of type () -> unit): Skip to the next track.
time (of type () -> float): Get a source's time, based on its assigned clock.

Callbacks:

on_collect (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source is collected
on_frame (of type (?before : bool, synchronous : bool, (() -> unit)) -> unit): Call a given handler on frame. When before is true, callback is executed before computing the frame and after otherwise
on_frame_checksum (of type (?before : ((string?) -> unit)?, synchronous : bool, ((cache : string?, string) -> unit)) -> unit): Call a given handler Register callbacks to compute frame checksums for debugging purposes. This is useful to track frame content changes through the streaming pipeline. The before callback is called before computing the frame with the checksum of the cached frame (if any, null otherwise). The main callback is called after computing the frame with the checksum of the generated frame and the remaining cache (if any).
on_metadata (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler to execute on each metadata
on_position (of type (position : {float}, ?remaining : bool, ?allow_partial : bool, synchronous : bool, ((float, [string * string]) -> unit)) -> unit): Call a given handler on track position. If remaining is false, callback is executed when position in track is more or equal to position. If remaining is true, callback is executed when remaining time in the current track is less or equal to position. Keep in mind that elapsed time is exact while remaining time is always estimated. Remaining time is usually more accurate for file-based sources. When allow_partial is true, if the current track ends before the offset position is reached, callback is still executed
on_shutdown (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source shuts down
on_track (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler on track marks
on_wake_up (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called after the source is asked to get ready

Composition methods:

composition_type (of type (() -> string).{set : (string) -> unit}): This source inherits composition from its effective source.
on_leave (of type ({source : source('A), track_sensitive : bool}) -> unit): Called after switching away from this source in a switch operator, once the transition using the ending source has completed. Receives a record with source (the source being left) and track_sensitive (true if the ending source's last frame had a track mark, i.e. it finished naturally; false if it was preempted mid-track). This function must return quickly as it runs in the streaming thread. The default depends on the active composition profile: file sources (source.composition.file) skip the source when preempted mid-track so it starts fresh on its next selection, and do nothing when it finished naturally; live sources (source.composition.live) do nothing.
on_select (of type ({ending : source('A)?, replay_metadata : bool, starting : source('A)}) -> source('A)): Called when selecting this source in a switch operator. Receives a record with starting (the incoming source) and ending (the previous source, or null when the ending source reached a track boundary). Returns the source to use. By default, both file and live profiles fade out ending when non-null (up to 1 second). The default is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
replay_metadata (of type {bool}): Whether to replay the latest metadata on this source when it is selected in a switch operator. Defaults to true. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
single (of type bool): Forbid the selection of this source for two consecutive tracks in switch operators. Defaults to false.
track_sensitive (of type {bool}): Whether this source insists on track boundaries in switch operators: when true, it prefers not to be interrupted mid-track and not to be started mid-track. A switch may only cut into a track that is still playing when at least one of the two sources involved has track_sensitive set to false; otherwise it waits for the playing source to reach a track boundary. File-based sources default to true; live network and hardware inputs default to false. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).

`native.once`

Create a source that plays only one track of the input source.

Type:

(source('c).{on_track : (synchronous : bool, (('a) -> unit)) -> 'b}) ->
source('c)

Composition:

This source inherits composition from its effective source.

Arguments:

(unlabeled) (of type source('c).{on_track : (synchronous : bool, (('a) -> unit)) -> 'b})

Methods:

buffered (of type () -> [string * float]): Length of buffered data.
clear_last_metadata (of type () -> unit): Clear the last metadata from the source.
clock (of type clock): The source's clock
duration (of type () -> float): Estimation of the duration of the current track.
elapsed (of type () -> float): Elapsed time in the current track.
fallible (of type bool): Indicate if a source may fail, i.e. may not be ready to stream.
generate_frame (of type () -> unit): Generate a frame from the source without consuming it. This can be useful in advanced cases where generating a frame is required to trigger some side effect like calculating some metadata before making a decision. You should make sure that the source is available before calling this function and it should only be called inside synchronous streaming loop callback such as on_frame!
id (of type () -> string): Identifier of the source.
insert_metadata (of type (?override : bool, ?new_track : bool, [string * string]) -> unit): Dynamically insert metadata in a stream. Inserts a new track with the given metadata if new_track is true. When override is false, metadata that the source provides itself takes precedence over the inserted one.
is_active (of type () -> bool): true if the source is active, i.e. it is continuously animated by its own clock whenever it is ready. Typically, true for outputs and sources such as input.http.
is_ready (of type () -> bool): Indicate if a source is ready to stream. This does not mean that the source is currently streaming, just that its resources are all properly initialized.
is_up (of type () -> bool): Indicate that the source can be asked to produce some data at any time. This is true when the source is currently being used or if it could be used at any time, typically inside a switch or fallback.
last_metadata (of type () -> [string * string]?): Return the last metadata from the source.
log (of type {level : (() -> int).{set : (int) -> unit}}): Get or set the source's log level, from 1 to 5.
register_command (of type (?usage : string?, description : string, string, ((string) -> string)) -> unit): Register a server command for this source. Command is registered under the source's id namespace when it gets up and de-registered when it gets down.
remaining (of type () -> float): Estimation of remaining time in the current track.
reset_last_metadata_on_track (of type (() -> bool).{set : (bool) -> unit}): If true, the source's last_metadata is reset on each new track. If a metadata is present along with the track mark, then it becomes the new last_metadata, otherwise, last_metadata becomes null`.
seek (of type (float) -> float): Seek forward, in seconds (returns the amount of time effectively seeked).
self_sync (of type () -> bool): Is the source currently controlling its own real-time loop.
self_sync_description (of type () -> string):
skip (of type () -> unit): Skip to the next track.
time (of type () -> float): Get a source's time, based on its assigned clock.

Callbacks:

on_collect (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source is collected
on_frame (of type (?before : bool, synchronous : bool, (() -> unit)) -> unit): Call a given handler on frame. When before is true, callback is executed before computing the frame and after otherwise
on_frame_checksum (of type (?before : ((string?) -> unit)?, synchronous : bool, ((cache : string?, string) -> unit)) -> unit): Call a given handler Register callbacks to compute frame checksums for debugging purposes. This is useful to track frame content changes through the streaming pipeline. The before callback is called before computing the frame with the checksum of the cached frame (if any, null otherwise). The main callback is called after computing the frame with the checksum of the generated frame and the remaining cache (if any).
on_metadata (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler to execute on each metadata
on_position (of type (position : {float}, ?remaining : bool, ?allow_partial : bool, synchronous : bool, ((float, [string * string]) -> unit)) -> unit): Call a given handler on track position. If remaining is false, callback is executed when position in track is more or equal to position. If remaining is true, callback is executed when remaining time in the current track is less or equal to position. Keep in mind that elapsed time is exact while remaining time is always estimated. Remaining time is usually more accurate for file-based sources. When allow_partial is true, if the current track ends before the offset position is reached, callback is still executed
on_shutdown (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source shuts down
on_track (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler on track marks
on_wake_up (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called after the source is asked to get ready

Composition methods:

composition_type (of type (() -> string).{set : (string) -> unit}): This source inherits composition from its effective source.
on_leave (of type ({source : source('A), track_sensitive : bool}) -> unit): Called after switching away from this source in a switch operator, once the transition using the ending source has completed. Receives a record with source (the source being left) and track_sensitive (true if the ending source's last frame had a track mark, i.e. it finished naturally; false if it was preempted mid-track). This function must return quickly as it runs in the streaming thread. The default depends on the active composition profile: file sources (source.composition.file) skip the source when preempted mid-track so it starts fresh on its next selection, and do nothing when it finished naturally; live sources (source.composition.live) do nothing.
on_select (of type ({ending : source('A)?, replay_metadata : bool, starting : source('A)}) -> source('A)): Called when selecting this source in a switch operator. Receives a record with starting (the incoming source) and ending (the previous source, or null when the ending source reached a track boundary). Returns the source to use. By default, both file and live profiles fade out ending when non-null (up to 1 second). The default is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
replay_metadata (of type {bool}): Whether to replay the latest metadata on this source when it is selected in a switch operator. Defaults to true. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
single (of type bool): Forbid the selection of this source for two consecutive tracks in switch operators. Defaults to false.
track_sensitive (of type {bool}): Whether this source insists on track boundaries in switch operators: when true, it prefers not to be interrupted mid-track and not to be started mid-track. A switch may only cut into a track that is still playing when at least one of the two sources involved has track_sensitive set to false; otherwise it waits for the playing source to reach a track boundary. File-based sources default to true; live network and hardware inputs default to false. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).

`native.sequence`

Play only one track of every successive source, except for the last one which is played as much as available.

Type:

(?id : string?,
 [source('a)
  .{
    buffered : () -> [string * float],
    clear_last_metadata : () -> unit,
    clock : clock,
    composition_type : (() -> string)
    .{set : (string) -> unit
    },
    duration : () -> float,
    elapsed : () -> float,
    fallible : bool,
    generate_frame : () -> unit,
    id : () -> string,
    insert_metadata : (?override : bool, ?new_track : bool,
                       [string * string]) -> unit,
    is_active : () -> bool,
    is_ready : () -> bool,
    is_up : () -> bool,
    last_metadata : () -> [string * string]?,
    log : 
    {level : (() -> int).{set : (int) -> unit}
    },
    on_collect : (synchronous : bool, (() -> unit)) -> unit,
    on_frame : (?before : bool, synchronous : bool, (() -> unit)) -> unit,
    on_frame_checksum : (?before : ((string?) -> unit)?, synchronous : bool,
                         ((cache : string?, string) -> unit)) -> unit,
    on_leave : ({source : source('a), track_sensitive : bool}) -> unit,
    on_metadata : (synchronous : bool, (([string * string]) -> unit)) -> unit,
    on_position : (position : {float}, ?remaining : bool,
                   ?allow_partial : bool, synchronous : bool,
                   ((float, [string * string]) -> unit)) -> unit,
    on_select : (
                 {
                   ending : source('a)?,
                   replay_metadata : bool,
                   starting : source('a)
                 }) -> source('a),
    on_shutdown : (synchronous : bool, (() -> unit)) -> unit,
    on_track : (synchronous : bool, (([string * string]) -> unit)) -> unit,
    on_wake_up : (synchronous : bool, (() -> unit)) -> unit,
    register_command : (?usage : string?, description : string, string,
                        ((string) -> string)) -> unit,
    remaining : () -> float,
    replay_metadata : {bool},
    reset_last_metadata_on_track : (() -> bool)
    .{set : (bool) -> unit
    },
    seek : (float) -> float,
    self_sync : () -> bool,
    self_sync_description : () -> string,
    single : bool,
    skip : () -> unit,
    time : () -> float,
    track_sensitive : {bool}
  }]) -> source('a)

Composition:

This source inherits composition from its effective source.

Arguments:

id (of type string?, which defaults to null): Force the value of the source ID.
(unlabeled) (of type [source('a) .{ buffered : () -> [string * float], clear_last_metadata : () -> unit, clock : clock, composition_type : (() -> string) .{set : (string) -> unit }, duration : () -> float, elapsed : () -> float, fallible : bool, generate_frame : () -> unit, id : () -> string, insert_metadata : (?override : bool, ?new_track : bool, [string * string]) -> unit, is_active : () -> bool, is_ready : () -> bool, is_up : () -> bool, last_metadata : () -> [string * string]?, log : {level : (() -> int).{set : (int) -> unit} }, on_collect : (synchronous : bool, (() -> unit)) -> unit, on_frame : (?before : bool, synchronous : bool, (() -> unit)) -> unit, on_frame_checksum : (?before : ((string?) -> unit)?, synchronous : bool, ((cache : string?, string) -> unit)) -> unit, on_leave : ({source : source('a), track_sensitive : bool}) -> unit, on_metadata : (synchronous : bool, (([string * string]) -> unit)) -> unit, on_position : (position : {float}, ?remaining : bool, ?allow_partial : bool, synchronous : bool, ((float, [string * string]) -> unit)) -> unit, on_select : ( { ending : source('a)?, replay_metadata : bool, starting : source('a) }) -> source('a), on_shutdown : (synchronous : bool, (() -> unit)) -> unit, on_track : (synchronous : bool, (([string * string]) -> unit)) -> unit, on_wake_up : (synchronous : bool, (() -> unit)) -> unit, register_command : (?usage : string?, description : string, string, ((string) -> string)) -> unit, remaining : () -> float, replay_metadata : {bool}, reset_last_metadata_on_track : (() -> bool) .{set : (bool) -> unit }, seek : (float) -> float, self_sync : () -> bool, self_sync_description : () -> string, single : bool, skip : () -> unit, time : () -> float, track_sensitive : {bool} }]): List of sources to play tracks from.

Methods:

buffered (of type () -> [string * float]): Length of buffered data.
clear_last_metadata (of type () -> unit): Clear the last metadata from the source.
clock (of type clock): The source's clock
current_source (of type () -> source('A)?): Return the source currently selected.
duration (of type () -> float): Estimation of the duration of the current track.
elapsed (of type () -> float): Elapsed time in the current track.
fallible (of type bool): Indicate if a source may fail, i.e. may not be ready to stream.
generate_frame (of type () -> unit): Generate a frame from the source without consuming it. This can be useful in advanced cases where generating a frame is required to trigger some side effect like calculating some metadata before making a decision. You should make sure that the source is available before calling this function and it should only be called inside synchronous streaming loop callback such as on_frame!
id (of type () -> string): Identifier of the source.
insert_metadata (of type (?override : bool, ?new_track : bool, [string * string]) -> unit): Dynamically insert metadata in a stream. Inserts a new track with the given metadata if new_track is true. When override is false, metadata that the source provides itself takes precedence over the inserted one.
is_active (of type () -> bool): true if the source is active, i.e. it is continuously animated by its own clock whenever it is ready. Typically, true for outputs and sources such as input.http.
is_ready (of type () -> bool): Indicate if a source is ready to stream. This does not mean that the source is currently streaming, just that its resources are all properly initialized.
is_up (of type () -> bool): Indicate that the source can be asked to produce some data at any time. This is true when the source is currently being used or if it could be used at any time, typically inside a switch or fallback.
last_metadata (of type () -> [string * string]?): Return the last metadata from the source.
log (of type {level : (() -> int).{set : (int) -> unit}}): Get or set the source's log level, from 1 to 5.
prepare (of type (source('A)) -> source('A).{activation : activation}): Prepare a source that will be returned later. Returned source has new activation attached to it and should be used to submit to the source later.
register_command (of type (?usage : string?, description : string, string, ((string) -> string)) -> unit): Register a server command for this source. Command is registered under the source's id namespace when it gets up and de-registered when it gets down.
remaining (of type () -> float): Estimation of remaining time in the current track.
reset_last_metadata_on_track (of type (() -> bool).{set : (bool) -> unit}): If true, the source's last_metadata is reset on each new track. If a metadata is present along with the track mark, then it becomes the new last_metadata, otherwise, last_metadata becomes null`.
seek (of type (float) -> float): Seek forward, in seconds (returns the amount of time effectively seeked).
self_sync (of type () -> bool): Is the source currently controlling its own real-time loop.
self_sync_description (of type () -> string):
skip (of type () -> unit): Skip to the next track.
time (of type () -> float): Get a source's time, based on its assigned clock.

Callbacks:

on_collect (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source is collected
on_frame (of type (?before : bool, synchronous : bool, (() -> unit)) -> unit): Call a given handler on frame. When before is true, callback is executed before computing the frame and after otherwise
on_frame_checksum (of type (?before : ((string?) -> unit)?, synchronous : bool, ((cache : string?, string) -> unit)) -> unit): Call a given handler Register callbacks to compute frame checksums for debugging purposes. This is useful to track frame content changes through the streaming pipeline. The before callback is called before computing the frame with the checksum of the cached frame (if any, null otherwise). The main callback is called after computing the frame with the checksum of the generated frame and the remaining cache (if any).
on_metadata (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler to execute on each metadata
on_position (of type (position : {float}, ?remaining : bool, ?allow_partial : bool, synchronous : bool, ((float, [string * string]) -> unit)) -> unit): Call a given handler on track position. If remaining is false, callback is executed when position in track is more or equal to position. If remaining is true, callback is executed when remaining time in the current track is less or equal to position. Keep in mind that elapsed time is exact while remaining time is always estimated. Remaining time is usually more accurate for file-based sources. When allow_partial is true, if the current track ends before the offset position is reached, callback is still executed
on_shutdown (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source shuts down
on_track (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler on track marks
on_wake_up (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called after the source is asked to get ready

Composition methods:

composition_type (of type (() -> string).{set : (string) -> unit}): This source inherits composition from its effective source.
on_leave (of type ({source : source('A), track_sensitive : bool}) -> unit): Called after switching away from this source in a switch operator, once the transition using the ending source has completed. Receives a record with source (the source being left) and track_sensitive (true if the ending source's last frame had a track mark, i.e. it finished naturally; false if it was preempted mid-track). This function must return quickly as it runs in the streaming thread. The default depends on the active composition profile: file sources (source.composition.file) skip the source when preempted mid-track so it starts fresh on its next selection, and do nothing when it finished naturally; live sources (source.composition.live) do nothing.
on_select (of type ({ending : source('A)?, replay_metadata : bool, starting : source('A)}) -> source('A)): Called when selecting this source in a switch operator. Receives a record with starting (the incoming source) and ending (the previous source, or null when the ending source reached a track boundary). Returns the source to use. By default, both file and live profiles fade out ending when non-null (up to 1 second). The default is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
replay_metadata (of type {bool}): Whether to replay the latest metadata on this source when it is selected in a switch operator. Defaults to true. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
single (of type bool): Forbid the selection of this source for two consecutive tracks in switch operators. Defaults to false.
track_sensitive (of type {bool}): Whether this source insists on track boundaries in switch operators: when true, it prefers not to be interrupted mid-track and not to be started mid-track. A switch may only cut into a track that is still playing when at least one of the two sources involved has track_sensitive set to false; otherwise it waits for the playing source to reach a track boundary. File-based sources default to true; live network and hardware inputs default to false. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).

`native.switch`

Select the first source whose predicate is true in a list. If the second argument is a getter, the source will be dynamically created.

Type:

(?id : string?, ?track_sensitive : bool, [{bool} * source('a)]) -> source('a)

Composition:

This source inherits composition from its effective source.

Arguments:

id (of type string?, which defaults to null): Force the value of the source ID.
track_sensitive (of type bool, which defaults to true): Re-select only on end of tracks.
(unlabeled) (of type [{bool} * source('a)]): Sources with the predicate telling when they can be played.

Methods:

buffered (of type () -> [string * float]): Length of buffered data.
clear_last_metadata (of type () -> unit): Clear the last metadata from the source.
clock (of type clock): The source's clock
current_source (of type () -> source('A)?): Return the source currently selected.
duration (of type () -> float): Estimation of the duration of the current track.
elapsed (of type () -> float): Elapsed time in the current track.
fallible (of type bool): Indicate if a source may fail, i.e. may not be ready to stream.
generate_frame (of type () -> unit): Generate a frame from the source without consuming it. This can be useful in advanced cases where generating a frame is required to trigger some side effect like calculating some metadata before making a decision. You should make sure that the source is available before calling this function and it should only be called inside synchronous streaming loop callback such as on_frame!
id (of type () -> string): Identifier of the source.
insert_metadata (of type (?override : bool, ?new_track : bool, [string * string]) -> unit): Dynamically insert metadata in a stream. Inserts a new track with the given metadata if new_track is true. When override is false, metadata that the source provides itself takes precedence over the inserted one.
is_active (of type () -> bool): true if the source is active, i.e. it is continuously animated by its own clock whenever it is ready. Typically, true for outputs and sources such as input.http.
is_ready (of type () -> bool): Indicate if a source is ready to stream. This does not mean that the source is currently streaming, just that its resources are all properly initialized.
is_up (of type () -> bool): Indicate that the source can be asked to produce some data at any time. This is true when the source is currently being used or if it could be used at any time, typically inside a switch or fallback.
last_metadata (of type () -> [string * string]?): Return the last metadata from the source.
log (of type {level : (() -> int).{set : (int) -> unit}}): Get or set the source's log level, from 1 to 5.
prepare (of type (source('A)) -> source('A).{activation : activation}): Prepare a source that will be returned later. Returned source has new activation attached to it and should be used to submit to the source later.
register_command (of type (?usage : string?, description : string, string, ((string) -> string)) -> unit): Register a server command for this source. Command is registered under the source's id namespace when it gets up and de-registered when it gets down.
remaining (of type () -> float): Estimation of remaining time in the current track.
reset_last_metadata_on_track (of type (() -> bool).{set : (bool) -> unit}): If true, the source's last_metadata is reset on each new track. If a metadata is present along with the track mark, then it becomes the new last_metadata, otherwise, last_metadata becomes null`.
seek (of type (float) -> float): Seek forward, in seconds (returns the amount of time effectively seeked).
self_sync (of type () -> bool): Is the source currently controlling its own real-time loop.
self_sync_description (of type () -> string):
skip (of type () -> unit): Skip to the next track.
time (of type () -> float): Get a source's time, based on its assigned clock.

Callbacks:

on_collect (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source is collected
on_frame (of type (?before : bool, synchronous : bool, (() -> unit)) -> unit): Call a given handler on frame. When before is true, callback is executed before computing the frame and after otherwise
on_frame_checksum (of type (?before : ((string?) -> unit)?, synchronous : bool, ((cache : string?, string) -> unit)) -> unit): Call a given handler Register callbacks to compute frame checksums for debugging purposes. This is useful to track frame content changes through the streaming pipeline. The before callback is called before computing the frame with the checksum of the cached frame (if any, null otherwise). The main callback is called after computing the frame with the checksum of the generated frame and the remaining cache (if any).
on_metadata (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler to execute on each metadata
on_position (of type (position : {float}, ?remaining : bool, ?allow_partial : bool, synchronous : bool, ((float, [string * string]) -> unit)) -> unit): Call a given handler on track position. If remaining is false, callback is executed when position in track is more or equal to position. If remaining is true, callback is executed when remaining time in the current track is less or equal to position. Keep in mind that elapsed time is exact while remaining time is always estimated. Remaining time is usually more accurate for file-based sources. When allow_partial is true, if the current track ends before the offset position is reached, callback is still executed
on_shutdown (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source shuts down
on_track (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler on track marks
on_wake_up (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called after the source is asked to get ready

Composition methods:

composition_type (of type (() -> string).{set : (string) -> unit}): This source inherits composition from its effective source.
on_leave (of type ({source : source('A), track_sensitive : bool}) -> unit): Called after switching away from this source in a switch operator, once the transition using the ending source has completed. Receives a record with source (the source being left) and track_sensitive (true if the ending source's last frame had a track mark, i.e. it finished naturally; false if it was preempted mid-track). This function must return quickly as it runs in the streaming thread. The default depends on the active composition profile: file sources (source.composition.file) skip the source when preempted mid-track so it starts fresh on its next selection, and do nothing when it finished naturally; live sources (source.composition.live) do nothing.
on_select (of type ({ending : source('A)?, replay_metadata : bool, starting : source('A)}) -> source('A)): Called when selecting this source in a switch operator. Receives a record with starting (the incoming source) and ending (the previous source, or null when the ending source reached a track boundary). Returns the source to use. By default, both file and live profiles fade out ending when non-null (up to 1 second). The default is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
replay_metadata (of type {bool}): Whether to replay the latest metadata on this source when it is selected in a switch operator. Defaults to true. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
single (of type bool): Forbid the selection of this source for two consecutive tracks in switch operators. Defaults to false.
track_sensitive (of type {bool}): Whether this source insists on track boundaries in switch operators: when true, it prefers not to be interrupted mid-track and not to be started mid-track. A switch may only cut into a track that is still playing when at least one of the two sources involved has track_sensitive set to false; otherwise it waits for the playing source to reach a track boundary. File-based sources default to true; live network and hardware inputs default to false. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).

`notify_metadata`

Use notify to display metadata info.

Type:

(?urgency : string, ?icon : string, ?timeout : float,
 ?display : (([string * string]) -> string), ?title : string, 'b
 .{on_metadata : (synchronous : bool, (([string * string]) -> unit)) -> 'a}) ->
'a

Arguments:

urgency (of type string, which defaults to "low"): Urgency (low|normal|critical).
icon (of type string, which defaults to "stock_smiley-22"): Icon filename or stock icon to display.
timeout (of type float, which defaults to 3.0): Timeout in seconds.
display (of type ([string * string]) -> string, which defaults to fun (m) -> ...): Function used to display a metadata packet.
title (of type string, which defaults to "Liquidsoap: new track"): Title of the notification message.
(unlabeled) (of type 'b.{on_metadata : (synchronous : bool, (([string * string]) -> unit)) -> 'a})

`osd_metadata`

Use X On Screen Display to display metadata info.

Type:

(?color : string, ?position : string, ?font : string,
 ?display : (([string * string]) -> string), 'b
 .{on_metadata : (synchronous : bool, (([string * string]) -> unit)) -> 'a}) ->
'a

Arguments:

color (of type string, which defaults to "green"): Color of the text.
position (of type string, which defaults to "top"): Position of the text (top|middle|bottom).
font (of type string, which defaults to "-*-courier-*-r-*-*-*-240-*-*-*-*-*-*"): Font used (xfontsel is your friend...)
display (of type ([string * string]) -> string, which defaults to fun (m) -> ...): Function used to display a metadata packet.
(unlabeled) (of type 'b.{on_metadata : (synchronous : bool, (([string * string]) -> unit)) -> 'a})

`overlap_sources`

Rotate between overlapping sources. Next track starts according to 'liq_start_next' offset metadata.

Type:

(?id : string?, ?normalize : bool, ?start_next : string,
 ?weights : [{float}],
 [source('d)
  .{
    on_metadata : (synchronous : bool, (([string * string]) -> unit)) -> unit,
    on_position : (synchronous : bool, allow_partial : bool,
                   position : (() -> float), (('a, 'b) -> unit)) -> unit,
    on_track : (synchronous : bool, (('c) -> unit)) -> unit
  }]) -> source('d)
where
  'd is a set of tracks to be muxed into a source and a set of internal tracks

Composition:

This source inherits composition from its effective source.

Arguments:

id (of type string?, which defaults to "overlap_sources"): Force the value of the source ID.
normalize (of type bool, which defaults to false)
start_next (of type string, which defaults to "liq_start_next"): Metadata field indicating when the next track should start, relative to current track's time.
weights (of type [{float}], which defaults to []): Relative weight of the sources in the sum. The empty list stands for the homogeneous distribution.
(unlabeled) (of type [source('d) .{ on_metadata : (synchronous : bool, (([string * string]) -> unit)) -> unit, on_position : (synchronous : bool, allow_partial : bool, position : (() -> float), (('a, 'b) -> unit)) -> unit, on_track : (synchronous : bool, (('c) -> unit)) -> unit }] where 'd is a set of tracks to be muxed into a source and a set of internal tracks): Sources to toggle from

Methods:

buffered (of type () -> [string * float]): Length of buffered data.
clear_last_metadata (of type () -> unit): Clear the last metadata from the source.
clock (of type clock): The source's clock
duration (of type () -> float): Estimation of the duration of the current track.
elapsed (of type () -> float): Elapsed time in the current track.
fallible (of type bool): Indicate if a source may fail, i.e. may not be ready to stream.
generate_frame (of type () -> unit): Generate a frame from the source without consuming it. This can be useful in advanced cases where generating a frame is required to trigger some side effect like calculating some metadata before making a decision. You should make sure that the source is available before calling this function and it should only be called inside synchronous streaming loop callback such as on_frame!
id (of type () -> string): Identifier of the source.
insert_metadata (of type (?override : bool, ?new_track : bool, [string * string]) -> unit): Dynamically insert metadata in a stream. Inserts a new track with the given metadata if new_track is true. When override is false, metadata that the source provides itself takes precedence over the inserted one.
is_active (of type () -> bool): true if the source is active, i.e. it is continuously animated by its own clock whenever it is ready. Typically, true for outputs and sources such as input.http.
is_ready (of type () -> bool): Indicate if a source is ready to stream. This does not mean that the source is currently streaming, just that its resources are all properly initialized.
is_up (of type () -> bool): Indicate that the source can be asked to produce some data at any time. This is true when the source is currently being used or if it could be used at any time, typically inside a switch or fallback.
last_metadata (of type () -> [string * string]?): Return the last metadata from the source.
log (of type {level : (() -> int).{set : (int) -> unit}}): Get or set the source's log level, from 1 to 5.
register_command (of type (?usage : string?, description : string, string, ((string) -> string)) -> unit): Register a server command for this source. Command is registered under the source's id namespace when it gets up and de-registered when it gets down.
remaining (of type () -> float): Estimation of remaining time in the current track.
reset_last_metadata_on_track (of type (() -> bool).{set : (bool) -> unit}): If true, the source's last_metadata is reset on each new track. If a metadata is present along with the track mark, then it becomes the new last_metadata, otherwise, last_metadata becomes null`.
seek (of type (float) -> float): Seek forward, in seconds (returns the amount of time effectively seeked).
self_sync (of type () -> bool): Is the source currently controlling its own real-time loop.
self_sync_description (of type () -> string):
skip (of type () -> unit): Skip to the next track.
time (of type () -> float): Get a source's time, based on its assigned clock.

Callbacks:

on_collect (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source is collected
on_frame (of type (?before : bool, synchronous : bool, (() -> unit)) -> unit): Call a given handler on frame. When before is true, callback is executed before computing the frame and after otherwise
on_frame_checksum (of type (?before : ((string?) -> unit)?, synchronous : bool, ((cache : string?, string) -> unit)) -> unit): Call a given handler Register callbacks to compute frame checksums for debugging purposes. This is useful to track frame content changes through the streaming pipeline. The before callback is called before computing the frame with the checksum of the cached frame (if any, null otherwise). The main callback is called after computing the frame with the checksum of the generated frame and the remaining cache (if any).
on_metadata (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler to execute on each metadata
on_position (of type (position : {float}, ?remaining : bool, ?allow_partial : bool, synchronous : bool, ((float, [string * string]) -> unit)) -> unit): Call a given handler on track position. If remaining is false, callback is executed when position in track is more or equal to position. If remaining is true, callback is executed when remaining time in the current track is less or equal to position. Keep in mind that elapsed time is exact while remaining time is always estimated. Remaining time is usually more accurate for file-based sources. When allow_partial is true, if the current track ends before the offset position is reached, callback is still executed
on_shutdown (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source shuts down
on_track (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler on track marks
on_wake_up (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called after the source is asked to get ready

Composition methods:

composition_type (of type (() -> string).{set : (string) -> unit}): This source inherits composition from its effective source.
on_leave (of type ({source : source('A), track_sensitive : bool}) -> unit where 'A is a set of tracks to be muxed into a source and a set of internal tracks): Called after switching away from this source in a switch operator, once the transition using the ending source has completed. Receives a record with source (the source being left) and track_sensitive (true if the ending source's last frame had a track mark, i.e. it finished naturally; false if it was preempted mid-track). This function must return quickly as it runs in the streaming thread. The default depends on the active composition profile: file sources (source.composition.file) skip the source when preempted mid-track so it starts fresh on its next selection, and do nothing when it finished naturally; live sources (source.composition.live) do nothing.
on_select (of type ({ending : source('A)?, replay_metadata : bool, starting : source('A)}) -> source('A) where 'A is a set of tracks to be muxed into a source and a set of internal tracks): Called when selecting this source in a switch operator. Receives a record with starting (the incoming source) and ending (the previous source, or null when the ending source reached a track boundary). Returns the source to use. By default, both file and live profiles fade out ending when non-null (up to 1 second). The default is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
replay_metadata (of type {bool}): Whether to replay the latest metadata on this source when it is selected in a switch operator. Defaults to true. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
single (of type bool): Forbid the selection of this source for two consecutive tracks in switch operators. Defaults to false.
track_sensitive (of type {bool}): Whether this source insists on track boundaries in switch operators: when true, it prefers not to be interrupted mid-track and not to be started mid-track. A switch may only cut into a track that is still playing when at least one of the two sources involved has track_sensitive set to false; otherwise it waits for the playing source to reach a track boundary. File-based sources default to true; live network and hardware inputs default to false. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).

`playlog`

Keep a record of played files. This is primarily useful to know when a song was last played and avoid repetitions.

Type:

(?duration : float, ?persistency : string?,
 ?hash : (([string * string]) -> string)) -> unit

Arguments:

duration (of type float, which defaults to inf): Duration (in seconds) after which songs are forgotten. By default, songs are not forgotten which means that the playlog will contain all the songs ever played.
persistency (of type string?, which defaults to null): Set a file name where the values are stored and loaded in case the script is restarted.
hash (of type ([string * string]) -> string, which defaults to fun (m) -> ...): Function to extract an identifier from the metadata. By default, the filename is used but we could return the artist to know when a song from a given artist was last played for instance.

Methods:

add (of type ([string * string]) -> unit): Record that file with given metadata has been played.
last (of type ([string * string]) -> float): How long ago a file was played (in seconds), infinity is returned if the song has never been played.

`prepend`

Prepend an extra track before every track. Set the metadata liq_prepend to false to inhibit prepending on one track.

Type:

(?id : string?, ?merge : bool, source('a)
 .{
   on_metadata : (synchronous : bool, (([string * string]) -> unit)) -> unit,
   on_track : (synchronous : bool, (([string * string]) -> unit)) -> unit
 }, (([string * string]) -> source('a)?)) -> source('a)

Composition:

This source inherits composition from its effective source.

Arguments:

id (of type string?, which defaults to "prepend")
merge (of type bool, which defaults to false): Merge the track with its appended track.
(unlabeled) (of type source('a) .{ on_metadata : (synchronous : bool, (([string * string]) -> unit)) -> unit, on_track : (synchronous : bool, (([string * string]) -> unit)) -> unit }): Given the metadata, build the source producing the track to append. The function can return null to prevent any track prepend.
(unlabeled) (of type ([string * string]) -> source('a)?)

Methods:

buffered (of type () -> [string * float]): Length of buffered data.
clear_last_metadata (of type () -> unit): Clear the last metadata from the source.
clock (of type clock): The source's clock
duration (of type () -> float): Estimation of the duration of the current track.
elapsed (of type () -> float): Elapsed time in the current track.
fallible (of type bool): Indicate if a source may fail, i.e. may not be ready to stream.
generate_frame (of type () -> unit): Generate a frame from the source without consuming it. This can be useful in advanced cases where generating a frame is required to trigger some side effect like calculating some metadata before making a decision. You should make sure that the source is available before calling this function and it should only be called inside synchronous streaming loop callback such as on_frame!
id (of type () -> string): Identifier of the source.
insert_metadata (of type (?override : bool, ?new_track : bool, [string * string]) -> unit): Dynamically insert metadata in a stream. Inserts a new track with the given metadata if new_track is true. When override is false, metadata that the source provides itself takes precedence over the inserted one.
is_active (of type () -> bool): true if the source is active, i.e. it is continuously animated by its own clock whenever it is ready. Typically, true for outputs and sources such as input.http.
is_ready (of type () -> bool): Indicate if a source is ready to stream. This does not mean that the source is currently streaming, just that its resources are all properly initialized.
is_up (of type () -> bool): Indicate that the source can be asked to produce some data at any time. This is true when the source is currently being used or if it could be used at any time, typically inside a switch or fallback.
last_metadata (of type () -> [string * string]?): Return the last metadata from the source.
log (of type {level : (() -> int).{set : (int) -> unit}}): Get or set the source's log level, from 1 to 5.
register_command (of type (?usage : string?, description : string, string, ((string) -> string)) -> unit): Register a server command for this source. Command is registered under the source's id namespace when it gets up and de-registered when it gets down.
remaining (of type () -> float): Estimation of remaining time in the current track.
reset_last_metadata_on_track (of type (() -> bool).{set : (bool) -> unit}): If true, the source's last_metadata is reset on each new track. If a metadata is present along with the track mark, then it becomes the new last_metadata, otherwise, last_metadata becomes null`.
seek (of type (float) -> float): Seek forward, in seconds (returns the amount of time effectively seeked).
selected (of type () -> source('A)?): Currently selected source.
self_sync (of type () -> bool): Is the source currently controlling its own real-time loop.
self_sync_description (of type () -> string):
skip (of type () -> unit): Skip to the next track.
time (of type () -> float): Get a source's time, based on its assigned clock.

Callbacks:

on_collect (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source is collected
on_frame (of type (?before : bool, synchronous : bool, (() -> unit)) -> unit): Call a given handler on frame. When before is true, callback is executed before computing the frame and after otherwise
on_frame_checksum (of type (?before : ((string?) -> unit)?, synchronous : bool, ((cache : string?, string) -> unit)) -> unit): Call a given handler Register callbacks to compute frame checksums for debugging purposes. This is useful to track frame content changes through the streaming pipeline. The before callback is called before computing the frame with the checksum of the cached frame (if any, null otherwise). The main callback is called after computing the frame with the checksum of the generated frame and the remaining cache (if any).
on_metadata (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler to execute on each metadata
on_position (of type (position : {float}, ?remaining : bool, ?allow_partial : bool, synchronous : bool, ((float, [string * string]) -> unit)) -> unit): Call a given handler on track position. If remaining is false, callback is executed when position in track is more or equal to position. If remaining is true, callback is executed when remaining time in the current track is less or equal to position. Keep in mind that elapsed time is exact while remaining time is always estimated. Remaining time is usually more accurate for file-based sources. When allow_partial is true, if the current track ends before the offset position is reached, callback is still executed
on_shutdown (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source shuts down
on_track (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler on track marks
on_wake_up (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called after the source is asked to get ready

Composition methods:

composition_type (of type (() -> string).{set : (string) -> unit}): This source inherits composition from its effective source.
on_leave (of type ({source : source('A), track_sensitive : bool}) -> unit): Called after switching away from this source in a switch operator, once the transition using the ending source has completed. Receives a record with source (the source being left) and track_sensitive (true if the ending source's last frame had a track mark, i.e. it finished naturally; false if it was preempted mid-track). This function must return quickly as it runs in the streaming thread. The default depends on the active composition profile: file sources (source.composition.file) skip the source when preempted mid-track so it starts fresh on its next selection, and do nothing when it finished naturally; live sources (source.composition.live) do nothing.
on_select (of type ({ending : source('A)?, replay_metadata : bool, starting : source('A)}) -> source('A)): Called when selecting this source in a switch operator. Receives a record with starting (the incoming source) and ending (the previous source, or null when the ending source reached a track boundary). Returns the source to use. By default, both file and live profiles fade out ending when non-null (up to 1 second). The default is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
replay_metadata (of type {bool}): Whether to replay the latest metadata on this source when it is selected in a switch operator. Defaults to true. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
single (of type bool): Forbid the selection of this source for two consecutive tracks in switch operators. Defaults to false.
track_sensitive (of type {bool}): Whether this source insists on track boundaries in switch operators: when true, it prefers not to be interrupted mid-track and not to be started mid-track. A switch may only cut into a track that is still playing when at least one of the two sources involved has track_sensitive set to false; otherwise it waits for the playing source to reach a track boundary. File-based sources default to true; live network and hardware inputs default to false. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).

`rotate.merge`

Same operator as rotate but merges tracks from each sources. For instance, rotate.merge([intro,main,outro]) creates a source that plays a sequence [intro,main,outro] as single track and loops back.

Type:

(?id : string?,
 [source('e)
  .{
    on_leave? : ({source : source('a), track_sensitive : bool}) -> unit,
    on_select? : (
                  {
                    ending : source('c)?,
                    replay_metadata : bool,
                    starting : source('b)
                  }) -> source('d),
    replay_metadata? : {bool},
    single? : bool,
    track_sensitive? : {bool},
    weight? : {int}
  }]) -> source('e)
where
  'e is a set of internal tracks and a set of tracks to be muxed into a source

Composition:

This source inherits composition from its effective source.

Arguments:

id (of type string?, which defaults to "rotate.merge"): Force the value of the source ID.
(unlabeled) (of type [source('e) .{ on_leave? : ({source : source('a), track_sensitive : bool}) -> unit, on_select? : ( { ending : source('c)?, replay_metadata : bool, starting : source('b) }) -> source('d), replay_metadata? : {bool}, single? : bool, track_sensitive? : {bool}, weight? : {int} }] where 'e is a set of internal tracks and a set of tracks to be muxed into a source): Sequence of sources to be merged.

Methods:

buffered (of type () -> [string * float]): Length of buffered data.
clear_last_metadata (of type () -> unit): Clear the last metadata from the source.
clock (of type clock): The source's clock
duration (of type () -> float): Estimation of the duration of the current track.
elapsed (of type () -> float): Elapsed time in the current track.
fallible (of type bool): Indicate if a source may fail, i.e. may not be ready to stream.
generate_frame (of type () -> unit): Generate a frame from the source without consuming it. This can be useful in advanced cases where generating a frame is required to trigger some side effect like calculating some metadata before making a decision. You should make sure that the source is available before calling this function and it should only be called inside synchronous streaming loop callback such as on_frame!
id (of type () -> string): Identifier of the source.
insert_metadata (of type (?override : bool, ?new_track : bool, [string * string]) -> unit): Dynamically insert metadata in a stream. Inserts a new track with the given metadata if new_track is true. When override is false, metadata that the source provides itself takes precedence over the inserted one.
is_active (of type () -> bool): true if the source is active, i.e. it is continuously animated by its own clock whenever it is ready. Typically, true for outputs and sources such as input.http.
is_ready (of type () -> bool): Indicate if a source is ready to stream. This does not mean that the source is currently streaming, just that its resources are all properly initialized.
is_up (of type () -> bool): Indicate that the source can be asked to produce some data at any time. This is true when the source is currently being used or if it could be used at any time, typically inside a switch or fallback.
last_metadata (of type () -> [string * string]?): Return the last metadata from the source.
log (of type {level : (() -> int).{set : (int) -> unit}}): Get or set the source's log level, from 1 to 5.
register_command (of type (?usage : string?, description : string, string, ((string) -> string)) -> unit): Register a server command for this source. Command is registered under the source's id namespace when it gets up and de-registered when it gets down.
remaining (of type () -> float): Estimation of remaining time in the current track.
reset_last_metadata_on_track (of type (() -> bool).{set : (bool) -> unit}): If true, the source's last_metadata is reset on each new track. If a metadata is present along with the track mark, then it becomes the new last_metadata, otherwise, last_metadata becomes null`.
seek (of type (float) -> float): Seek forward, in seconds (returns the amount of time effectively seeked).
selected (of type () -> source('A)? where 'A is a set of internal tracks and a set of tracks to be muxed into a source): Currently selected source.
self_sync (of type () -> bool): Is the source currently controlling its own real-time loop.
self_sync_description (of type () -> string):
skip (of type () -> unit): Skip to the next track.
time (of type () -> float): Get a source's time, based on its assigned clock.

Callbacks:

on_collect (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source is collected
on_frame (of type (?before : bool, synchronous : bool, (() -> unit)) -> unit): Call a given handler on frame. When before is true, callback is executed before computing the frame and after otherwise
on_frame_checksum (of type (?before : ((string?) -> unit)?, synchronous : bool, ((cache : string?, string) -> unit)) -> unit): Call a given handler Register callbacks to compute frame checksums for debugging purposes. This is useful to track frame content changes through the streaming pipeline. The before callback is called before computing the frame with the checksum of the cached frame (if any, null otherwise). The main callback is called after computing the frame with the checksum of the generated frame and the remaining cache (if any).
on_metadata (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler to execute on each metadata
on_position (of type (position : {float}, ?remaining : bool, ?allow_partial : bool, synchronous : bool, ((float, [string * string]) -> unit)) -> unit): Call a given handler on track position. If remaining is false, callback is executed when position in track is more or equal to position. If remaining is true, callback is executed when remaining time in the current track is less or equal to position. Keep in mind that elapsed time is exact while remaining time is always estimated. Remaining time is usually more accurate for file-based sources. When allow_partial is true, if the current track ends before the offset position is reached, callback is still executed
on_shutdown (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source shuts down
on_track (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler on track marks
on_wake_up (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called after the source is asked to get ready

Composition methods:

composition_type (of type (() -> string).{set : (string) -> unit}): This source inherits composition from its effective source.
on_leave (of type ({source : source('A), track_sensitive : bool}) -> unit where 'A is a set of internal tracks and a set of tracks to be muxed into a source): Called after switching away from this source in a switch operator, once the transition using the ending source has completed. Receives a record with source (the source being left) and track_sensitive (true if the ending source's last frame had a track mark, i.e. it finished naturally; false if it was preempted mid-track). This function must return quickly as it runs in the streaming thread. The default depends on the active composition profile: file sources (source.composition.file) skip the source when preempted mid-track so it starts fresh on its next selection, and do nothing when it finished naturally; live sources (source.composition.live) do nothing.
on_select (of type ({ending : source('A)?, replay_metadata : bool, starting : source('A)}) -> source('A) where 'A is a set of internal tracks and a set of tracks to be muxed into a source): Called when selecting this source in a switch operator. Receives a record with starting (the incoming source) and ending (the previous source, or null when the ending source reached a track boundary). Returns the source to use. By default, both file and live profiles fade out ending when non-null (up to 1 second). The default is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
replay_metadata (of type {bool}): Whether to replay the latest metadata on this source when it is selected in a switch operator. Defaults to true. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
single (of type bool): Forbid the selection of this source for two consecutive tracks in switch operators. Defaults to false.
track_sensitive (of type {bool}): Whether this source insists on track boundaries in switch operators: when true, it prefers not to be interrupted mid-track and not to be started mid-track. A switch may only cut into a track that is still playing when at least one of the two sources involved has track_sensitive set to false; otherwise it waits for the playing source to reach a track boundary. File-based sources default to true; live network and hardware inputs default to false. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).

`server.insert_metadata`

Register a server/telnet command to update a source's metadata. Returns a new source, which will receive the updated metadata. The command has the following format: insert key1="val1",key2="val2",...

Type:

('d
 .{
   register_command : (description : string, usage : string, string,
                       (('b.{insert_metadata : ([string * string]) -> 'a}) ->
                        string)) -> 'c
 }) -> 'd

Arguments:

(unlabeled) (of type 'd .{ register_command : (description : string, usage : string, string, (('b.{insert_metadata : ([string * string]) -> 'a}) -> string)) -> 'c })

Methods:

register_command (of type (description : string, usage : string, string, (('B.{insert_metadata : ([string * string]) -> 'C}) -> string)) -> 'A):

`skipper`

Regularly skip tracks from a source (useful for testing skipping).

Type:

(?every : {float}, 'b
 .{on_frame : ((() -> unit)) -> 'a, skip : () -> unit, time : () -> float}) ->
'b

Arguments:

every (of type {float}, which defaults to 5.0): How often to skip tracks.
(unlabeled) (of type 'b.{on_frame : ((() -> unit)) -> 'a, skip : () -> unit, time : () -> float}): The stream.

Methods:

on_frame (of type ((() -> unit)) -> 'A):
skip (of type () -> unit):
time (of type () -> float):

`source.cue`

Generate a CUE file for the source. This function will generate a new track in the file for each metadata of the source. This function tries to map metadata to the appropriate CUE file standard values. You can use the map_metadata argument to add your own pre-processing. The following metadata are recognized on tracks: "title", "artist", "album", "isrc", and "cue_year".

Type:

(?title : string?, ?performer : string?, ?file : {string?},
 ?file_type : string?, ?comment : string?, ?year : 'a?,
 ?map_metadata : (([string * string]) -> [string * string]),
 ?last_tracks : int?, ?temp_dir : string?, ?deduplicate_using : [string],
 ?delete : bool, {string}, source('b)) -> source('b)
where 'b is a set of tracks to be muxed into a source

Composition:

This source uses file composition by default.

Arguments:

title (of type string?, which defaults to null): Title of the stream.
performer (of type string?, which defaults to null)
file (of type {string?}, which defaults to null): File where the stream is stored.
file_type (of type string?, which defaults to null): Format in which the stream is stored.
comment (of type string?, which defaults to null): Comment about the stream.
year (of type 'a?, which defaults to null): Year for the stream.
map_metadata (of type ([string * string]) -> [string * string], which defaults to fun (m) -> ...): Function to apply to metadata before writing the CUE file (useful for pre-processing metadata).
last_tracks (of type int?, which defaults to null): Only report the number of last tracks.
temp_dir (of type string?, which defaults to null): Temporary directory for atomic write.
deduplicate_using (of type [string], which defaults to ["title", "artist", "album", "isrc", "cue_year"]): To avoid duplicate entries, duplicate metadata are filtered. Set this to a list of labels to use for detecting duplicated metadata.
delete (of type bool, which defaults to true): Delete the CUE files when starting if it exists.
(unlabeled) (of type {string}): Path where the CUE file should be written.
(unlabeled) (of type source('b) where 'b is a set of tracks to be muxed into a source)

Methods:

buffered (of type () -> [string * float]): Length of buffered data.
clear_last_metadata (of type () -> unit): Clear the last metadata from the source.
clock (of type clock): The source's clock
duration (of type () -> float): Estimation of the duration of the current track.
elapsed (of type () -> float): Elapsed time in the current track.
fallible (of type bool): Indicate if a source may fail, i.e. may not be ready to stream.
generate_frame (of type () -> unit): Generate a frame from the source without consuming it. This can be useful in advanced cases where generating a frame is required to trigger some side effect like calculating some metadata before making a decision. You should make sure that the source is available before calling this function and it should only be called inside synchronous streaming loop callback such as on_frame!
id (of type () -> string): Identifier of the source.
insert_metadata (of type (?override : bool, ?new_track : bool, [string * string]) -> unit): Dynamically insert metadata in a stream. Inserts a new track with the given metadata if new_track is true. When override is false, metadata that the source provides itself takes precedence over the inserted one.
is_active (of type () -> bool): true if the source is active, i.e. it is continuously animated by its own clock whenever it is ready. Typically, true for outputs and sources such as input.http.
is_ready (of type () -> bool): Indicate if a source is ready to stream. This does not mean that the source is currently streaming, just that its resources are all properly initialized.
is_up (of type () -> bool): Indicate that the source can be asked to produce some data at any time. This is true when the source is currently being used or if it could be used at any time, typically inside a switch or fallback.
last_metadata (of type () -> [string * string]?): Return the last metadata from the source.
log (of type {level : (() -> int).{set : (int) -> unit}}): Get or set the source's log level, from 1 to 5.
register_command (of type (?usage : string?, description : string, string, ((string) -> string)) -> unit): Register a server command for this source. Command is registered under the source's id namespace when it gets up and de-registered when it gets down.
remaining (of type () -> float): Estimation of remaining time in the current track.
reset_last_metadata_on_track (of type (() -> bool).{set : (bool) -> unit}): If true, the source's last_metadata is reset on each new track. If a metadata is present along with the track mark, then it becomes the new last_metadata, otherwise, last_metadata becomes null`.
seek (of type (float) -> float): Seek forward, in seconds (returns the amount of time effectively seeked).
self_sync (of type () -> bool): Is the source currently controlling its own real-time loop.
self_sync_description (of type () -> string):
skip (of type () -> unit): Skip to the next track.
time (of type () -> float): Get a source's time, based on its assigned clock.

Callbacks:

on_collect (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source is collected
on_frame (of type (?before : bool, synchronous : bool, (() -> unit)) -> unit): Call a given handler on frame. When before is true, callback is executed before computing the frame and after otherwise
on_frame_checksum (of type (?before : ((string?) -> unit)?, synchronous : bool, ((cache : string?, string) -> unit)) -> unit): Call a given handler Register callbacks to compute frame checksums for debugging purposes. This is useful to track frame content changes through the streaming pipeline. The before callback is called before computing the frame with the checksum of the cached frame (if any, null otherwise). The main callback is called after computing the frame with the checksum of the generated frame and the remaining cache (if any).
on_metadata (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler to execute on each metadata
on_position (of type (position : {float}, ?remaining : bool, ?allow_partial : bool, synchronous : bool, ((float, [string * string]) -> unit)) -> unit): Call a given handler on track position. If remaining is false, callback is executed when position in track is more or equal to position. If remaining is true, callback is executed when remaining time in the current track is less or equal to position. Keep in mind that elapsed time is exact while remaining time is always estimated. Remaining time is usually more accurate for file-based sources. When allow_partial is true, if the current track ends before the offset position is reached, callback is still executed
on_shutdown (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called when source shuts down
on_track (of type (synchronous : bool, (([string * string]) -> unit)) -> unit): Call a given handler on track marks
on_wake_up (of type (synchronous : bool, (() -> unit)) -> unit): Call a given handler to be called after the source is asked to get ready

Composition methods:

composition_type (of type (() -> string).{set : (string) -> unit}): This source uses file composition by default.
on_leave (of type ({source : source('A), track_sensitive : bool}) -> unit where 'A is a set of tracks to be muxed into a source): Called after switching away from this source in a switch operator, once the transition using the ending source has completed. Receives a record with source (the source being left) and track_sensitive (true if the ending source's last frame had a track mark, i.e. it finished naturally; false if it was preempted mid-track). This function must return quickly as it runs in the streaming thread. The default depends on the active composition profile: file sources (source.composition.file) skip the source when preempted mid-track so it starts fresh on its next selection, and do nothing when it finished naturally; live sources (source.composition.live) do nothing.
on_select (of type ({ending : source('A)?, replay_metadata : bool, starting : source('A)}) -> source('A) where 'A is a set of tracks to be muxed into a source): Called when selecting this source in a switch operator. Receives a record with starting (the incoming source) and ending (the previous source, or null when the ending source reached a track boundary). Returns the source to use. By default, both file and live profiles fade out ending when non-null (up to 1 second). The default is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
replay_metadata (of type {bool}): Whether to replay the latest metadata on this source when it is selected in a switch operator. Defaults to true. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).
single (of type bool): Forbid the selection of this source for two consecutive tracks in switch operators. Defaults to false.
track_sensitive (of type {bool}): Whether this source insists on track boundaries in switch operators: when true, it prefers not to be interrupted mid-track and not to be started mid-track. A switch may only cut into a track that is still playing when at least one of the two sources involved has track_sensitive set to false; otherwise it waits for the playing source to reach a track boundary. File-based sources default to true; live network and hardware inputs default to false. The value is looked up at runtime from the active composition profile (source.composition.file or source.composition.live depending on composition_type).

append​

autocue.plot​

chop​

cross.plot​

fallback.skip​

map_first_track​

native.fallback​

native.once​

native.sequence​

native.switch​

notify_metadata​

osd_metadata​

overlap_sources​

playlog​

prepend​

rotate.merge​

server.insert_metadata​

skipper​

source.cue​

`append`

`autocue.plot`

`chop`

`cross.plot`

`fallback.skip`

`map_first_track`

`native.fallback`

`native.once`

`native.sequence`

`native.switch`

`notify_metadata`

`osd_metadata`

`overlap_sources`

`playlog`

`prepend`

`rotate.merge`

`server.insert_metadata`

`skipper`

`source.cue`