Saving RTP stream to file using membrane framework

Elixir Framework Forums Membrane Forum
1

I’m playing around with membrane, trying to save an RTP stream from an IP camera to file. Using code from some demos I managed to get the the video stream and send it to a hls stream to make sure it works. At this point my code looks like this:

  def handle_init(opts) do
    %{audio_port: audio_port, video_port: video_port} = opts

    spec = %ParentSpec{
      children: [
        video_src: %Membrane.Element.UDP.Source{
          local_port_no: video_port,
        },
        audio_src: %Membrane.Element.UDP.Source{
          local_port_no: audio_port,
        },
        rtp: %RTP.SessionBin{
          secure?: false,
        },
      ],
      links: [
        link(:video_src) |> via_in(:rtp_input) |> to(:rtp),
        link(:audio_src) |> via_in(:rtp_input) |> to(:rtp)
      ]
    }

    {{:ok, spec: spec}, %{}}
  end

  defp handle_stream(%{video: video_ssrc, table: table}) do
    spec = %ParentSpec{
      children: %{
        video_parser: %Membrane.H264.FFmpeg.Parser{framerate: {30, 1}, alignment: :au, attach_nalus?: true},
        video_payloader: Membrane.MP4.Payloader.H264,
        video_cmaf_muxer: Membrane.MP4.CMAF.Muxer,

        hls: %Membrane.HTTPAdaptiveStream.Sink {
          manifest_module: Membrane.HTTPAdaptiveStream.HLS,
          target_window_duration: 10 |> Membrane.Time.seconds(),
          storage: %Membrane.HTTPAdaptiveStream.Storages.FileStorage{directory: "output"}
        }


      },
      links: [
        link(:rtp)
        |> via_out(Pad.ref(:output, video_ssrc))
        |> to(:video_parser)

        |> to(:video_payloader)
        |> to(:video_cmaf_muxer)
        |> via_in(:input)

        |> to(:hls)
      ],
      stream_sync: :sinks
    }

    [spec: spec]
  end

I’d like to replace the hls output and save the stream to a avi or mp4 file. Is it possible?

Thanks!

1 Like
2

Hi @eloy,
I am not sure if this is possible with current mp4_plugin.

What you can try is to save this stream as h264 video and play it with ffmpeg or use ffmpeg to convert it to mp4 file.

To save something to file

You can use membrane_file_plugin.

To play h264 video using ffmpeg

ffplay -f h264 video.h264.
The -f option stands for format.

To convert h264 file to mp4 one

ffmpeg -framerate 24 -i video.h264 -c copy video.mp4(source)
The -i option stands for input.
The -c option stands for codec so that -c copy means that streams will be copied into output file i.e. no reencoding will be performed.
The -framerate is video framerate. I think you can try to omit it.

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3

I dunno if RTP is same as RTMP, but Underjord blog has a post on how he made the streamed video saved while it also streamed. Maybe worth a look?

4

RTP and RTMP are totally different protocols and the blog shows how to dump to HLS, not MP4 :wink: Membrane can dump both RTP and RTMP to HLS, while dumping to MP4 requires transcoding. Dumping to MP4 without transcoding is not really straightforward, but support for that is coming too: https://github.com/membraneframework/membrane_mp4_plugin/pull/38.

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