An Endpoint responsible for communicatiing with WebRTC client.

It is responsible for sending and receiving media tracks from other WebRTC clients (e.g. web browsers).

Signalling

In order to operate correctly, this endpoint requires that the business logic implements the signalling channel to the client it represents. Implementation details are not important to endpoint.

Signalling in WebRTC is used to eg. facilitate SDP negotiation or send notifications regarding the session. This endpoint uses an abstraction of Media Events to achieve this. A Media Event is a black box message sent between the Client Library and this endpoint.

The business logic will receive an encoded media event in binary form from both the endpoint and the client library. It's only responsibility is to feed the binary to either the endpoint or the client library.

Message Protocol Definition

The business logic must receive media_event_message_t/0 message from the endpoint and forward it to the client over the implemented signalling channel. Mind you, this message will be wrapped with Membrane.RTC.Engine.Message.EndpointMessage.t/0

Example

@impl GenServer
def handle_info(%Membrane.RTC.Engine.Message.EndpointMessage{endpoint_id: endpoint, message: {:media_event, _event} = message}, state) do
  send state.channels[endpoint], message
  {:noreply, state}
end

Simmilarily, it must forward all media events it receives over the signalling channel to the endpoint by sending a media_event_message_t/0 to it.

Example.

@impl GenServer
def handle_info({:media_event, origin, event}, state) do
  endpoint_id = state.client_channel_to_endpoint_id[origin]
  Engine.message_endpoint(endpoint_id, {:media_event, event})
  {:noreply, state}
end

Client libraries

The following client libraries for handling signalling messages are available:

• Typescript library intended for use in web browsers
• Android native library
• IOS native library

Monitoring track activity

WebRTC Endpoint only monitors simulcast tracks activity, meaning that it never emits Membrane.RTC.Engine.Event.TrackVariantPaused event for non-simulcast tracks. The main reason is that it's impossible to tell if the screensharing track is inactive or not sending any packets because it contains static content.

Bin options

Passed via struct Membrane.RTC.Engine.Endpoint.WebRTC.t/0

• rtc_engine

  pid()

  Required
  Pid of parent Engine

• direction

  EndpointBin.direction()

  Default value: :sendrecv
  Direction of WebRTC Endpoint. Determines whether EndpointBin can send, receive or both send and receive media. For more information refer to t:EndpointBin.direction/0.

• ice_name

  String.t()

  Required
  Ice name is used in creating credentials for ice connnection

• handshake_opts

  Keyword.t()

  Default value: []
  Keyword list with options for handshake module. For more information please refer to Membrane.ICE.Bin

• filter_codecs

  ({RTPMapping.t(), FMTP.t() | nil} -> boolean())

  Default value: &Membrane.WebRTC.SDP.filter_encodings/1
  Defines function which will filter SDP m-line by codecs

• log_metadata

  :list

  Default value: []
  Logger metadata used for endpoint bin and all its descendants

• webrtc_extensions

  [module()]

  Default value: []
  List of WebRTC extensions to use.

  Each module has to implement Membrane.WebRTC.Extension.t(). See membrane_webrtc_plugin documentation for a list of possible extensions.

• extensions

  %{(encoding_name :: atom() | :any) => [Membrane.RTP.SessionBin.extension_t()]}

  Default value: %{}
  A map pointing from encoding names to lists of extensions that should be used for given encodings. Encoding ":any" indicates that extensions should be applied regardless of encoding.

  A sample usage would be to add silence discarder to OPUS tracks when VAD extension is enabled. It can greatly reduce CPU usage in rooms when there are a lot of people but only a few of them are actively speaking.

• integrated_turn_domain

  binary() | nil

  Default value: nil
  Domain address of integrated TURN Servers. Required for TLS TURN

• integrated_turn_options

  Membrane.ICE.Endpoint.integrated_turn_options_t()

  Default value: []

• owner

  pid()

  Required
  Pid of parent all notifications will be send to.

  To see possible notifications please refer to module docs.

• trace_context

  :list

  Default value: []
  Trace context for otel propagation

• parent_span

  :opentelemetry.span_ctx() | nil

  Default value: nil
  Parent span of webrtc_endpoint.life_span

• video_tracks_limit

  integer() | nil

  Default value: nil
  Maximal number of video tracks that will be sent to the the browser at the same time.

  This variable indicates how many video tracks should be sent to the browser at the same time. If nil all video tracks this Membrane.RTC.Engine.Endpoint.WebRTC receives will be sent.

• rtcp_receiver_report_interval

  Membrane.Time.t() | nil

  Default value: nil
  Receiver reports's generation interval, set to nil to avoid reports generation

• rtcp_sender_report_interval

  Membrane.Time.t() | nil

  Default value: nil
  Sender reports's generation interval, set to nil to avoid reports generation

• simulcast_config

  SimulcastConfig.t()

  Default value: %Membrane.RTC.Engine.Endpoint.WebRTC.SimulcastConfig{enabled: false, initial_target_variant: &Membrane.RTC.Engine.Endpoint.WebRTC.SimulcastConfig.initial_target_variant/1}
  Simulcast configuration

• metadata

  any()

  Default value: nil
  Endpoint metadata

• telemetry_label

  Membrane.TelemetryMetrics.label()

  Default value: []
  Label passed to Membrane.TelemetryMetrics functions

• toilet_capacity

  pos_integer()

  Default value: 200
  TrackReceiver toilet capacity

Pads

:input

Accepted formats:

_any

:output

Accepted formats:

_any