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• OpenCV+ffmpeg : Set max_analyze_duration ?

  3 avril 2013, par Christian Jonassen

  import sys
  
  import cv
  
  
  
  video = "http://192.168.1.15:8000/video.mjpg" # from motion
  
  capture = cv.CaptureFromFile(video)
  
  print capture
  
  cv.NamedWindow('Stream', 1 )
  
  
  
  while True:
  
    frame = cv.QueryFrame(capture)
  
  
  
    if frame is None:
  
      print "No frame, exiting program"
  
      break
  
    else:
  
      cv.ShowImage('Stream', frame)
  
      cv.WaitKey(20)

  , which sort of works. Meaning that after a while, I get

  Using network protocols without global network initialization. Please use avformat_network_init(), this will become mandatory later.
  
  Using network protocols without global network initialization. Please use avformat_network_init(), this will become mandatory later.
  
  [mjpeg @ 0xb46720] max_analyze_duration reached
  
  [mjpeg @ 0xb46720] Estimating duration from bitrate, this may be inaccurate
  
  Using network protocols without global network initialization. Please use avformat_network_init(), this will become mandatory later.
  
  Using network protocols without global network initialization. Please use avformat_network_init(), this will become mandatory later.
  
  [mjpeg @ 0xb46720] max_analyze_duration reached
  
  [mjpeg @ 0xb46720] Estimating duration from bitrate, this may be inaccurate
  
  <capture 0x7f0aed25c630="0x7f0aed25c630">
  
  </capture>

  The stream then works fine (it's a bit speedy in the start).

  It makes sense : FFMPEG finds the stream mysterious, and therefore analyzes it for the maximum duration, which makes the buffer full, and hence the speediness at the start. Now, is there a way I can (without recompiling FFMPEG) set max_analyze_duration, or otherwise pass some hints to FFMPEG so that it doesn't analyse the stream until max_analyze_duration has passed ?

  The stream is from the motion program : an MJPEG stream of 10 FPS with 640x480.

• FFMPEG libraries : Bitstream "h264_mp4toannexb" filter does not work

  25 décembre 2013, par user2677612

  We are using FFmpeg libraries git-ee94362 libavformat v55.2.100. Our purpose is to mux two streams (video and audio) into M3U8 playlist using HLS.

  We are using AV_CODEC_ID_H264 output encoder, AV_PIX_FMT_YUV420P output video pixel format and CODEC_FLAG_GLOBAL_HEADER flag for the encoder.

  The last causes us to use "h264_mp4toannexb" bit stream filter.

  So, here is the code snippet :

  AVPacket outpkt = {0};
  
  int isGotVideoPacket = 0;
  
  
  
  av_init_packet(&outpkt);
  
  
  
  out_video_frame->pts = (int64_t) (video_frame_count * in_video_frame_duration / av_q2d(out_video_stream->time_base));
  
  
  
  int ret = avcodec_encode_video2(enc_out_video_ctx, &outpkt, out_video_frame[i], &isGotVideoPacket);
  
  
  
  assert(0 <= ret);
  
  
  
  if ((1 == isGotVideoPacket) && (0 < outpkt.size)) {
  
  
  
       AVPacket new_outpkt = outpkt;
  
  
  
       if ((AVBitStreamFilterContext*) 0 != vbsf_ctx) {
  
            AVPacket new_outpkt = outpkt;
  
  
  
             ret = av_bitstream_filter_filter(vbsf_ctx, enc_out_video_ctx, (const char*)0, &new_outpkt.data, &new_outpkt.size, outpkt.data, outpkt.size, outpkt.flags & AV_PKT_FLAG_KEY);
  
  
  
             if (ret > 0)
  
             {
  
                outpkt = new_outpkt;
  
             }
  
             else 
  
             {
  
                // We get ret = -22
  
                char errbuf[128] = ""; 
  
  
  
                // Both the functions get "Error number -22 occurred" that don't explain anything
  
                av_strerror (ret, errbuf, 128);
  
                av_make_error_string (errbuf, 128, ret);          
  
              }
  
  
  
              assert(0 <= ret);
  
  
  
       }
  
  
  
       outpkt->stream_index = output_video_stream->index;
  
  
  
       // If to comment av_bitstream_filter_filter() and "if-else", then
  
       // At frame #37 we get the following error from av_interleaved_write_frame():
  
       // [mpegts @ 09628140] H.264 bitstream malformed, no startcode found, use the h264_mp4toannexb bitstream filter (-bsf h264_mp4toannexb).
  
       ret = av_interleaved_write_frame(ofmt_ctx, &outpkt);
  
  
  
       assert(0 <= ret);                          
  
   }

  Our questions :

  1. What is the meaning of the "-22" error from av_bitstream_filter_filter()?
  
  2. Where can we get full FFMPEG error code description list?
  
  3. If we are using av_bitstream_filter_filter() right? If no, what is the right way?

  Andrey Mochenov.

• Prepare mp4 videos for Media Source Extensions API using ffmpeg

  6 février 2018, par ler

  This command produce init.mp4 + bunch of m4s files, i’m trying to play them using MSE :

  ffmpeg -i <input file="file" /> -f hls -hls_segment_type fmp4 -c:v copy playlist.m3u8

  This is the client side code i’m using :

  var socket = io();
  
  var video = document.querySelector('video');
  
  var mimeCodec = 'video/mp4; codecs="avc1.64000d,mp4a.40.2"'; 
  
  if ('MediaSource' in window && MediaSource.isTypeSupported(mimeCodec)) {
  
      var mediaSource = new MediaSource;
  
      video.src = URL.createObjectURL(mediaSource);
  
      mediaSource.addEventListener('sourceopen', sourceOpen);
  
  } else {
  
      console.error('Unsupported MIME type or codec: ', mimeCodec);
  
  }
  
  function sourceOpen (_) {
  
    var mediaSource = this;
  
    var sourceBuffer = mediaSource.addSourceBuffer(mimeCodec);
  
    sourceBuffer.mode = 'sequence'; 
  
    socket.on('broadcast', function (newPiece) {
  
        // here i'm getting the buffer of the video  == buffer
  
        sourceBuffer.addEventListener('updateend', function (_) {
  
          video.play().then(function() { }).catch(function(error) { });
  
        });
  
        sourceBuffer.appendBuffer(buffer); // when the seconde video comes i append it's buffer
  
    })
  
  };

  Everything works fine when i send init.mp4 file followed by playlist0.m4s, playlist1.m4s, playlist2.m4s, .....
  But when i try to play init.mp4 file followed immediately 6,7,8 not 0,1,2 meaning playlist6.m4s, playlist7.m4s, playlist8.m4s, ...., it didn’t work.
  I don’t know why, this supposed to be live video, the viewer that is watching the live from the beginning gets init.mp4, playlist0.m4s, playlist1.m4s, playlist2.m4s, .....
  Someone that came after 5 minutes gets something like this init.mp4, playlist32.m4s, playlist33.m4s, playlist34.m4s, .... and so on, but so far it works only for the viewer that get’s init.mp4, playlist0.m4s, playlist1.m4s, playlist2.m4s, ..... the video can’t play for the others