Membrane element providing parser for H264 encoded video stream. Uses the parser provided by FFmpeg.

By default, this parser splits the stream into h264 access units, each of which is a sequence of NAL units corresponding to one video frame, and equips them with the following metadata entries under :h264 key:

• key_frame?: boolean - determines whether the frame is a h264 I frame.

Setting custom packetization options affects metadata, see alignment and attach_nalus? options for details.

This Parser is also capable of handling out-of-band parameters in the form of Decoder Configuration Record. To inject it, simply send Membrane.H264.RemoteStream.t/0 stream_format containing the Decoder Configuration Record to this element. There are however some limitations:

• Membrane.H264.RemoteStream.t/0 stream_format needs to be send only before the first buffer. Sending them during the stream will cause an error
• SPS and PPS will be extracted from Decoder Configuration Record and added to the payload of the very first buffer without any checks of in-band parameters. This might result in duplicated SPS and PPS. It shouldn't be a problem, unless you send an incorrect Decoder Configuration Record that doesn't match the stream.

element-options

Element options

Passed via struct Membrane.H264.FFmpeg.Parser.t/0

• framerate

  H264.framerate_t() | nil

  Default value: nil
  Framerate of video stream, see Membrane.H264.framerate_t/0

• sps

  binary()

  Default value: ""
  Sequence Parameter Set NAL unit - if absent in the stream, should be provided via this option.

• pps

  binary()

  Default value: ""
  Picture Parameter Set NAL unit - if absent in the stream, should be provided via this option.

• alignment

  :au | :nal

  Default value: :au
  Stream units carried by each output buffer. See Membrane.H264.alignment_t/0.

  If alignment is :nal, the following metadata entries are added:

  • type - h264 nalu type
  • new_access_unit: access_unit_metadata - added whenever the new access unit starts. access_unit_metadata is the metadata that would be merged into the buffer metadata normally (if alignment was :au).
  • end_access_unit: true - added for each NALu that ends an access unit.

• attach_nalus?

  boolean()

  Default value: false
  Determines whether to attach NAL units list to the metadata when alignment option is set to :au. For details see Membrane.H264.nalu_in_metadata_t/0.

• skip_until_keyframe?

  boolean()

  Default value: false
  Determines whether to drop the stream until the first key frame is received.

• skip_until_parameters?

  boolean()

  Default value: true
  Determines whether to drop the stream until the first set of SPS and PPS is received.

• max_frame_reorder

  non_neg_integer()

  Default value: 15
  Defines the maximum expected number of consequent b-frames in the stream.

pads

Pads

input

:input

Accepted formats:

%format{} when format in [Membrane.RemoteStream, H264, H264.RemoteStream]

output

:output

Accepted formats:

%H264{}