Version: 2.3.3

Metadata

`file.cover`

Obtain cover-art for a file. null is returned in case there is no such information.

Type:

(string) -> string
.{
  color_depth? : int,
  description? : string,
  format? : string,
  height? : int,
  mime : string,
  number_of_colors? : int?,
  picture_type? : int,
  width? : int}?

Arguments:

(unlabeled) (of type string): File from which the cover should be obtained

`metadata.artist`

Extract artist from metadata.

Type:

([string * string]) -> string

Arguments:

(unlabeled) (of type [string * string])

`metadata.comment`

Extract comment from metadata.

Type:

([string * string]) -> string

Arguments:

(unlabeled) (of type [string * string])

`metadata.cover`

Extract cover from metadata. This function implements cover extraction for the following formats: coverart (ogg), apic (flac, mp3) and pic (mp3).

Type:

(?coverart_mime : string?, [string * string]) -> string
.{
  color_depth? : int,
  description? : string,
  format? : string,
  height? : int,
  mime : string,
  number_of_colors? : int?,
  picture_type? : int,
  width? : int}?

Arguments:

coverart_mime (of type string?, which defaults to null): Mime type to use for "coverart" metadata. Support disabled if null.
(unlabeled) (of type [string * string]): Metadata from which the cover should be extracted.

`metadata.cover.remove`

Remove cover metadata. This is mostly useful in order not to flood logs with coverart when logging metadata.

Type:

([string * string]) -> [string * string]

Arguments:

(unlabeled) (of type [string * string])

`metadata.deduplicate`

Remove duplicate metadata in a source.

Type:

(?id : string?, ?using : [string]?, source('a)) -> source('a)
where 'a is a set of tracks to be muxed into a source

Arguments:

id (of type string?, which defaults to "metadata.deduplicate"): Source id
using (of type [string]?, which defaults to null): Labels to use to compare the metadata. Defaults to all of them when null.
(unlabeled) (of type source('a) where 'a is a set of tracks to be muxed into a source): source

Methods:

buffered (of type () -> [string * float]): Length of buffered data.
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.
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.
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.
skip (of type () -> unit): Skip to the next track.
time (of type () -> float): Get a source's time, based on its assigned clock.

`metadata.export`

Cleanup metadata for export. This is used to remove Liquidsoap's internal metadata entries before sending them. List of exported metadata is set using settings.encoder.metadata.export.set.

Type:

([string * string]) -> [string * string]

Arguments:

(unlabeled) (of type [string * string])

`metadata.filename`

Extract filename from metadata.

Type:

([string * string]) -> string

Arguments:

(unlabeled) (of type [string * string])

`metadata.getter`

Create a getter from a metadata: this is a string, whose value can be changed with a metadata.

Type:

(string, 'a, 'c.{on_metadata : (((['a * string]) -> unit)) -> 'b}) ->
() -> string where 'a is an orderable type

Arguments:

(unlabeled) (of type string): Initial value.
(unlabeled) (of type anything that is an orderable type): Metadata on which the value should be updated.
(unlabeled) (of type 'c.{on_metadata : (((['a * string]) -> unit)) -> 'b} where 'a is an orderable type): Source containing the metadata.

`metadata.getter.float`

Create a float getter from a metadata: this is a float, whose value can be changed with a metadata.

Type:

(float, 'a, 'c.{on_metadata : (((['a * string]) -> unit)) -> 'b}) ->
() -> float where 'a is an orderable type

Arguments:

(unlabeled) (of type float): Initial value.
(unlabeled) (of type anything that is an orderable type): Metadata on which the value should be updated.
(unlabeled) (of type 'c.{on_metadata : (((['a * string]) -> unit)) -> 'b} where 'a is an orderable type): Source containing the metadata.

`metadata.getter.source.float`

Create a float getter from a metadata: this is a float, whose value can be changed with a metadata. This function also returns the source.

Type:

(float, string, source('a)) ->
source('a)
.{
  buffered : () -> [string * float],
  clock : clock,
  duration : () -> float,
  elapsed : () -> float,
  fallible : bool,
  id : () -> string,
  is_active : () -> bool,
  is_ready : () -> bool,
  is_up : () -> bool,
  last_metadata : () -> [string * string]?,
  log : 
  {level : (() -> int).{set : (int) -> unit}
  },
  on_metadata : ((([string * string]) -> unit)) -> unit,
  on_shutdown : ((() -> unit)) -> unit,
  on_track : ((([string * string]) -> unit)) -> unit,
  on_wake_up : ((() -> unit)) -> unit,
  register_command : (?usage : string?, description : string, string,
                      ((string) -> string)) -> unit,
  remaining : () -> float,
  reset_last_metadata_on_track : (() -> bool)
  .{set : (bool) -> unit
  },
  seek : (float) -> float,
  self_sync : () -> bool,
  skip : () -> unit,
  time : () -> float
} * (() -> float)

Arguments:

(unlabeled) (of type float): Initial value.
(unlabeled) (of type string): Metadata on which the value should be updated.
(unlabeled) (of type source('a)): Source containing the metadata.

`metadata.json.parse`

Parse metadata from JSON object.

Type:

(string) -> [string * string] as json.object

Arguments:

(unlabeled) (of type string)

`metadata.json.stringify`

Export metadata as JSON object. Cover art, if found, is extracted using metadata.cover and exported with key "cover" and exported using string.data_uri.encode.

Type:

(?coverart_mime : string?, ?base64 : bool, ?compact : bool, ?json5 : bool,
 [string * string]) -> string

Arguments:

coverart_mime (of type string?, which defaults to null): Mime type to use for "coverart" metadata. Support disasbled if null.
base64 (of type bool, which defaults to true)
compact (of type bool, which defaults to false): Output compact text.
json5 (of type bool, which defaults to false): Use json5 extended spec.
(unlabeled) (of type [string * string])

`metadata.replaygain`

Extract the ReplayGain from the metadata (in dB).

Type:

([string * string]) -> float?

Arguments:

(unlabeled) (of type [string * string]): Metadata from which the ReplayGain should be extracted.

`metadata.title`

Extract title from metadata.

Type:

([string * string]) -> string

Arguments:

(unlabeled) (of type [string * string])

`string.apic.parse`

Parse APIC ID3v2 tags (such as those obtained in the APIC tag from file.metadata.id3v2). The returned values are: mime, picture type, description, and picture data.

Type:

(string) -> string

Arguments:

(unlabeled) (of type string): APIC data.

Methods:

description (of type string): Description
mime (of type string): Mime type
picture_type (of type int): Picture type

`string.pic.parse`

Parse PIC ID3v2 tags (such as those obtained in the PIC tag from file.metadata.id3v2). The returned values are: format, picture type, description, and picture data.

Type:

(string) -> string

Arguments:

(unlabeled) (of type string): PIC data.

Methods:

description (of type string): Description
format (of type string): Picture format
picture_type (of type int): Picture type

`track.metadata.deduplicate`

Remove duplicate metadata in a track.

Type:

(?id : string?, ?using : [string]?, metadata) -> metadata

Arguments:

id (of type string?, which defaults to "track.metadata.deduplicate")
using (of type [string]?, which defaults to null): Labels to use to compare the metadata. Defaults to all of them when null.
(unlabeled) (of type metadata)

file.cover​

metadata.artist​

metadata.comment​

metadata.cover​

metadata.cover.remove​

metadata.deduplicate​

metadata.export​

metadata.filename​

metadata.getter​

metadata.getter.float​

metadata.getter.source.float​

metadata.json.parse​

metadata.json.stringify​

metadata.replaygain​

metadata.title​

string.apic.parse​

string.pic.parse​

track.metadata.deduplicate​

`file.cover`

`metadata.artist`

`metadata.comment`

`metadata.cover`

`metadata.cover.remove`

`metadata.deduplicate`

`metadata.export`

`metadata.filename`

`metadata.getter`

`metadata.getter.float`

`metadata.getter.source.float`

`metadata.json.parse`

`metadata.json.stringify`

`metadata.replaygain`

`metadata.title`

`string.apic.parse`

`string.pic.parse`

`track.metadata.deduplicate`