View Source Membrane.RTC.Engine.Track (Membrane RTC Engine v0.23.0)
Module representing media track.
Media track is a single audio or video. Tracks that are related to each other (e.g. audio from microphone that corresponds to video from a web cam) can be grouped into the same stream by assigning each of them the same stream id.
Summary
Functions
Returns depayloader for given track.
Creates a new track.
Checks whether track is a simulcast one or not.
Generates stream id, that can be used to mark tracks belonging to the same stream.
Returns list of supported track variants.
Types
@type encoding() :: atom()
@type framerate() :: {non_neg_integer(), non_neg_integer()} | nil
@type id() :: String.t()
@type opts_t() :: [ id: String.t(), active?: boolean(), variants: [variant()], metadata: any(), ctx: map(), payload_type: non_neg_integer() | nil, framerate: framerate() ]
Options that can be passed to new/7.
If not provided:
id- will be generatedactive?- truevariants-[:high]metadata-nilctx-%{}
For more information refer to t/0.
@type t() :: %Membrane.RTC.Engine.Track{ active?: boolean(), clock_rate: Membrane.RTP.clock_rate_t(), ctx: map(), disabled_variants: [variant()], encoding: encoding(), fmtp: ExSDP.Attribute.FMTP.t(), framerate: framerate(), id: id(), metadata: any(), origin: String.t(), payload_type: non_neg_integer() | nil, stream_id: String.t(), type: :audio | :video, variants: [variant()] }
This module contains:
type- audio or video,stream_id- media stream this track belongs to. Relationship between tracks (e.g. audio and video) can be indicated by assigning each of them the samestream_id. Onestream_idcan be assign to any number of tracks.id- track idorigin- id of Endpoint this track belongs toencoding- track encodingvariants- list of possible track variants. Refer tovariant/0.clock_rate- track clock ratefmtp- struct describing format specific parameters e.g. for H264 it containsprofile_level_idactive?- indicates whether track is still available or not (because client left a room)metadata- any data passed by user to be linked with this trackctx- any data Endpoints need to associate withMembrane.RTC.Engine.Track.t()for internal usageframerate- track framerate. It's up to endpoints whether they set this field or not but if they do, they should only set it for video tracks with constant framerate. For audio tracks, framerate should always benil. Defaults tonil.
@type variant() :: :high | :medium | :low
Possible track variants.
The usage should be as follows:
:high- main track variant:medium- lower (in terms of quality) track variant:low- the lowest track variant
Audio tracks can have only one variant - :high.
Functions
@spec get_depayloader(t()) :: Membrane.ChildrenSpec.child_definition() | nil
Returns depayloader for given track.
Depayloader can be used to unpack RTP stream i.e. get data out of RTP packets.
Returns Membrane child specification or nil if depayloader
couldn't be determined.
Examples
@impl true
def handle_pad_added(Pad.ref(:input, track_id) = pad, _ctx, state) do
children = %{
{:track_receiver, track_id} => %TrackReceiver{
track: Map.fetch!(state.tracks, track_id),
initial_target_variant: :high
},
{:depayloader, track.id} => get_depayloader(track),
{:serializer, track_id} => Membrane.Stream.Serializer,
{:sink, track_id} => %Membrane.File.Sink{
location: Path.join(state.output_dir_path, track_id)
}
}
links = [
link_bin_input(pad)
|> to({:track_receiver, track_id})
|> to({:depayloader, track.id})
|> to({:serializer, track_id})
|> to({:sink, track_id})
]
{{:ok, spec: %ParentSpec{children: children, links: links}}, state}
endnew(type, stream_id, origin, encoding, clock_rate, fmtp, opts \\ [])
View Source@spec new( :audio | :video, String.t(), String.t(), encoding(), Membrane.RTP.clock_rate_t(), ExSDP.Attribute.FMTP.t(), opts_t() ) :: t()
Creates a new track.
Tracks belonging to the same stream should have the same stream_id,
that can be generated with stream_id/0.
Checks whether track is a simulcast one or not.
@spec stream_id() :: String.t()
Generates stream id, that can be used to mark tracks belonging to the same stream.
@spec supported_variants() :: [variant()]
Returns list of supported track variants.