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?, 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
• (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.
• 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.

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.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.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?, metadata) -> metadata

Arguments:

• id (of type string?, which defaults to "track.metadata.deduplicate")
• (unlabeled) (of type metadata)