Source / Visualization

server.rms

Register a command that outputs the RMS of the returned source.

Type:

(?id : string?, source(audio=pcm('a), 'b)) -> source(audio=pcm('a), 'b)

Arguments:

• id (of type string?, which defaults to null): Force the value of the source ID.
• (unlabeled) (of type source(audio=pcm('a), 'b))

Methods:

• buffered (of type () -> [string * float]): Length of buffered data.
• 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.
• id (of type () -> string): Identifier of the source.
• 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.
• on_metadata (of type ((([string * string]) -> unit)) -> unit): Call a given handler on metadata packets.
• on_shutdown (of type ((() -> unit)) -> unit): Register a function to be called when source shuts down.
• on_track (of type ((([string * string]) -> unit)) -> unit): Call a given handler on new tracks.
• on_wake_up (of type ((() -> unit)) -> unit): Register a function to be called after the source is asked to get ready. This is when, for instance, the source's final ID is set.
• remaining (of type () -> float): Estimation of remaining time in the current track.
• rms (of type () -> float): Current value for the RMS volume.
• 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.
• skip (of type () -> unit): Skip to the next track.
• time (of type () -> float): Get a source's time, based on its assigned clock.

video.vumeter

VU meter: display the audio volume (RMS in dB). This adds a video track to the source.

Type:

(?rms_min : float, ?rms_max : float, ?window : float, ?color : int,
 ?persistence : float, 'b
 .{audio : pcm('a), metadata? : metadata, track_marks? : track_marks}) ->
source(audio=pcm('a), video=canvas('c), 'b)
where 'b is a set of tracks to be muxed into a source

Arguments:

• rms_min (of type float, which defaults to -35.): Minimal volume (dB).
• rms_max (of type float, which defaults to 0.): Maximal volume (dB).
• window (of type float, which defaults to 0.1): Duration in seconds of volume computation.
• color (of type int, which defaults to 16711680): Color of the display (0xRRGGBB).
• persistence (of type float, which defaults to 0.): Persistence of the display (s).
• (unlabeled) (of type 'b.{audio : pcm('a), metadata? : metadata, track_marks? : track_marks} where 'b is a set of tracks to be muxed into a source)

Methods:

• buffered (of type () -> [string * float]): Length of buffered data.
• 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.
• id (of type () -> string): Identifier of the source.
• 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.
• on_metadata (of type ((([string * string]) -> unit)) -> unit): Call a given handler on metadata packets.
• on_shutdown (of type ((() -> unit)) -> unit): Register a function to be called when source shuts down.
• on_track (of type ((([string * string]) -> unit)) -> unit): Call a given handler on new tracks.
• on_wake_up (of type ((() -> unit)) -> unit): Register a function to be called after the source is asked to get ready. This is when, for instance, the source's final ID is set.
• remaining (of type () -> float): Estimation of remaining time in the current track.
• 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.
• skip (of type () -> unit): Skip to the next track.
• time (of type () -> float): Get a source's time, based on its assigned clock.

vumeter

VU meter: display the audio volume (RMS in dB) on the standard output.

Type:

(?rms_min : float, ?rms_max : float, ?window : float, ?scroll : bool,
 source(audio=pcm('a), 'b)) -> source(audio=pcm('a), 'b)

Arguments:

• rms_min (of type float, which defaults to -25.): Minimal volume (dB).
• rms_max (of type float, which defaults to -5.): Maximal volume (dB).
• window (of type float, which defaults to 0.5): Duration in seconds of volume computation.
• scroll (of type bool, which defaults to false): Update the display in the same line.
• (unlabeled) (of type source(audio=pcm('a), 'b))

Methods:

• buffered (of type () -> [string * float]): Length of buffered data.
• 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.
• id (of type () -> string): Identifier of the source.
• 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.
• on_metadata (of type ((([string * string]) -> unit)) -> unit): Call a given handler on metadata packets.
• on_shutdown (of type ((() -> unit)) -> unit): Register a function to be called when source shuts down.
• on_track (of type ((([string * string]) -> unit)) -> unit): Call a given handler on new tracks.
• on_wake_up (of type ((() -> unit)) -> unit): Register a function to be called after the source is asked to get ready. This is when, for instance, the source's final ID is set.
• remaining (of type () -> float): Estimation of remaining time in the current track.
• rms (of type () -> float): Current value for the RMS volume.
• 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.
• skip (of type () -> unit): Skip to the next track.
• time (of type () -> float): Get a source's time, based on its assigned clock.