Membrane.RTP.SessionBin (Membrane RTP plugin v0.6.1) View Source

Bin handling one RTP session, that may consist of multiple incoming and outgoing RTP streams.

Incoming streams

Incoming RTP streams can be connected via :rtp_input pads. As each pad can provide multiple RTP streams, they are distinguished basing on SSRC. Once a new stream is received, bin sends new_stream_notification_t/0 notification, meaning the parent should link Pad.ref(:output, ssrc) pad to consuming components. The stream is then depayloaded and forwarded via said pad.

Outgoing streams

To create an RTP stream, the source stream needs to be connected via Pad.ref(:input, ssrc) pad and the sink - via Pad.ref(:rtp_output, ssrc). At least one of :encoding or :payload_type options of :rtp_output pad must be provided too.

Payloaders and depayloaders

Payloaders are Membrane elements that transform stream so that it can be put into RTP packets, while depayloaders work the other way round. Different codecs require different payloaders and depayloaders. Thus, to send or receive given codec via this bin, proper payloader/depayloader is needed. Payloaders and depayloaders can be found in membrane_rtp_X_plugin packages, where X stands for codec name. It's enough when such plugin is added to dependencies.

RTCP

RTCP packets are received via :rtcp_input and sent via :rtcp_output pad. Only one instance of each of them can be linked. RTCP packets should be delivered to each involved peer that supports RTCP.

Bin options

Passed via struct Membrane.RTP.SessionBin.t/0

  • fmt_mapping

    %{RTP.payload_type_t() => {RTP.encoding_name_t(), RTP.clock_rate_t()}}

    Default value: %{}
    Mapping of the custom payload types ( > 95)

  • custom_payloaders

    %{RTP.encoding_name_t() => module()}

    Default value: %{}
    Mapping from encoding names to custom payloader modules

  • custom_depayloaders

    %{RTP.encoding_name_t() => module()}

    Default value: %{}
    Mapping from encoding names to custom depayloader modules

  • rtcp_interval

    Time.t()

    Default value: 5 |> Membrane.Time.seconds()
    Interval between sending subseqent RTCP receiver reports.

  • receiver_ssrc_generator

    (local_ssrcs :: [pos_integer], remote_ssrcs :: [pos_integer] -> ssrc :: pos_integer)

    Default value: &Membrane.RTP.SessionBin.generate_receiver_ssrc/2
    Function generating receiver SSRCs. Default one generates random SSRC that is not in local_ssrcs nor remote_ssrcs.

  • secure?

    boolean

    Default value: false
    Specifies whether to use SRTP. Requires adding srtp dependency to work.

  • srtp_policies

    [ExLibSRTP.Policy.t()]

    Default value: []
    List of SRTP policies to use for decrypting packets. Used only when secure? is set to true. See ExLibSRTP.Policy.t/0 for details.

  • receiver_srtp_policies

    [ExLibSRTP.Policy.t()] | nil

    Default value: nil
    List of SRTP policies to use for encrypting receiver reports and other receiver RTCP packets. Used only when secure? is set to true. Defaults to the value of srtp_policies. See ExLibSRTP.Policy.t/0 for details.

Pads

:rtcp_input

Availability:on_request
CapsMembrane.RemoteStream, restrictions:<br />&nbsp;&nbsp;type: :packetized,<br />&nbsp;&nbsp;content_format: one_of([nil, Membrane.RTCP])
Demand unit:buffers
Direction:input
Mode:pull
Name:rtcp_input

:rtp_input

Availability:on_request
CapsMembrane.RemoteStream, restrictions:<br />&nbsp;&nbsp;type: :packetized,<br />&nbsp;&nbsp;content_format: one_of([nil, Membrane.RTP])
Demand unit:buffers
Direction:input
Mode:pull
Name:rtp_input

:input

Availability:on_request
Caps:any
Demand unit:buffers
Direction:input
Mode:pull
Name:input

:rtcp_output

Availability:on_request
CapsMembrane.RemoteStream, restrictions:<br />&nbsp;&nbsp;type: :packetized,<br />&nbsp;&nbsp;content_format: Membrane.RTCP
Demand unit:buffers
Direction:output
Mode:pull
Name:rtcp_output

:rtp_output

Availability:on_request
CapsMembrane.RemoteStream, restrictions:<br />&nbsp;&nbsp;type: :packetized,<br />&nbsp;&nbsp;content_format: Membrane.RTP
Demand unit:buffers
Direction:output
Mode:pull
Name:rtp_output

Options:

  • payload_type

    RTP.payload_type_t() | nil

    Default value: nil
    Payload type of output stream. If not provided, determined from :encoding.

  • encoding

    RTP.encoding_name_t() | nil

    Default value: nil
    Encoding name of output stream. If not provided, determined from :payload_type.

  • clock_rate

    integer() | nil

    Default value: nil
    Clock rate to use. If not provided, determined from :payload_type.

:output

Availability:on_request
Caps:any
Demand unit:buffers
Direction:output
Mode:pull
Name:output

Options:

  • encoding

    RTP.encoding_name_t() | nil

    Default value: nil
    Encoding name determining depayloader which will be used to produce output stream from RTP stream.

  • clock_rate

    integer() | nil

    Default value: nil
    Clock rate to use. If not provided, determined from fmt_mapping or defaults registered by proper plugins i.e. Membrane.RTP.X.Plugin where X is the name of codec corresponding to encoding.

  • extensions

    [:vad]

    Default value: []
    List of extensions. Currently :vad is only supported.

    • :vad will turn on Voice Activity Detection mechanism firing appropriate notifications when needed. Should be set only for audio tracks. For more information refer to Membrane.RTP.VAD module documentation.

Link to this section Summary

Types

Options for pad :output

Options for pad :rtp_output

t()

Struct containing options for Membrane.RTP.SessionBin

Functions

Returns pads descriptions for Membrane.RTP.SessionBin

Returns description of options available for this module

Link to this section Types

Link to this type

new_stream_notification_t()

View Source

Specs

new_stream_notification_t() ::
  Membrane.RTP.SSRCRouter.new_stream_notification_t()

Specs

output_pad_opts_t() :: [
  encoding: Membrane.RTP.encoding_name_t() | nil,
  clock_rate: integer() | nil,
  extensions: [:vad]
]

Options for pad :output

Link to this type

rtp_output_pad_opts_t()

View Source

Specs

rtp_output_pad_opts_t() :: [
  payload_type: Membrane.RTP.payload_type_t() | nil,
  encoding: Membrane.RTP.encoding_name_t() | nil,
  clock_rate: integer() | nil
]

Options for pad :rtp_output

Specs

t() :: %Membrane.RTP.SessionBin{
  custom_depayloaders: %{required(Membrane.RTP.encoding_name_t()) => module()},
  custom_payloaders: %{required(Membrane.RTP.encoding_name_t()) => module()},
  fmt_mapping: %{
    required(Membrane.RTP.payload_type_t()) =>
      {Membrane.RTP.encoding_name_t(), Membrane.RTP.clock_rate_t()}
  },
  receiver_srtp_policies: [ExLibSRTP.Policy.t()] | nil,
  receiver_ssrc_generator:
    (local_ssrcs :: [pos_integer()], remote_ssrcs :: [pos_integer()] ->
       ssrc :: pos_integer()),
  rtcp_interval: Membrane.Time.t(),
  secure?: boolean(),
  srtp_policies: [ExLibSRTP.Policy.t()]
}

Struct containing options for Membrane.RTP.SessionBin

Link to this section Functions

Specs

membrane_pads() :: [{Membrane.Pad.name_t(), Membrane.Pad.description_t()}]

Returns pads descriptions for Membrane.RTP.SessionBin

Specs

options() :: keyword()

Returns description of options available for this module