membrane_h264_ffmpeg_plugin crashes using Encoder profile :constrained_baseline

[olegokunevych]

While testing different Encoder profiles, found out that :constrained_baseline crashes pipeline.
However other profiles doesn't crash entire pipeline.

Pipeline example:

child(:source, %Membrane.RTMP.SourceBin{
  client_ref: state.client_ref
})
|> via_out(:video)
|> child(:video_parser, %Membrane.H264.Parser{
  output_alignment: :au,
  output_stream_structure: :annexb,
})
|> child(:h264_decoder, %Membrane.H264.FFmpeg.Decoder{})
|> child(:h264_encoder, %Membrane.H264.FFmpeg.Encoder{
  profile: :constrained_baseline
})
|> child(:output_video_parser, %Membrane.H264.Parser{
  output_alignment: :nalu,
  output_stream_structure: :annexb,
  repeat_parameter_sets: true
})

Actual result:

12:22:57.245 [error] pid=<0.899.0> mfa=Membrane.Core.Element.handle_info/2  <0.854.0>/{:endpoint, "63555e37-bd5b-4062-b08d-b1573536841b"}/:h264_encoder Error occured in Membrane Element:
** (RuntimeError) Failed to create native encoder: :codec_open
    (membrane_h264_ffmpeg_plugin 0.32.3) lib/membrane_h264_ffmpeg/encoder.ex:213: anonymous fn/1 in Membrane.H264.FFmpeg.Encoder.handle_stream_format/4
    (membrane_core 1.1.1) lib/membrane/core/callback_handler.ex:139: Membrane.Core.CallbackHandler.exec_callback/4
    (membrane_core 1.1.1) lib/membrane/core/callback_handler.ex:69: Membrane.Core.CallbackHandler.exec_and_handle_callback/5
    (membrane_core 1.1.1) lib/membrane/core/element/stream_format_controller.ex:82: Membrane.Core.Element.StreamFormatController.exec_handle_stream_format/4
    (membrane_core 1.1.1) lib/membrane/core/element.ex:237: Membrane.Core.Element.handle_info/2
    (stdlib 5.2) gen_server.erl:1095: :gen_server.try_handle_info/3
    (stdlib 5.2) gen_server.erl:1183: :gen_server.handle_msg/6
    (stdlib 5.2) proc_lib.erl:241: :proc_lib.init_p_do_apply/3

Expected result:

Pipeline works with all profiles described in the doc https://hexdocs.pm/membrane_h264_format/0.6.1/Membrane.H264.html#t:profile/0

[gBillal]

Actually the H264 format defines the set of possible profiles, it doesn't mention that all of them should be supported by the encoder. The x264 library used by ffmpeg (used in its turn by membrane_h264_ffmpeg_plugin) does not support constrained_baseline profile.