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• ffmpeg avcodec_decode_video2 function error codes

  7 mai 2018, par gaby

  i use at the function avcodec_decode_video2 at the flowing way :

  if (packet.isEOF()) {
  
      AVPacket eofpkt;
  
      av_init_packet(&eofpkt);
  
      eofpkt.data = NULL;
  
      eofpkt.size = 0;
  
      ret = avcodec_decode_video2(d.codec_ctx, d.frame, &got_frame_ptr, &eofpkt);
  
  } else {
  
      ret = avcodec_decode_video2(d.codec_ctx, d.frame, &got_frame_ptr, (AVPacket*)packet.asAVPacket());
  
  }
  
  //qDebug("pic_type=%c", av_get_picture_type_char(d.frame->pict_type));
  
  d.undecoded_size = qMin(packet.data.size() - ret, packet.data.size());
  
  if (ret < 0) {
  
      //qWarning("[VideoDecoderFFmpegBase] %s", av_err2str(ret));
  
      return false;
  
  }
  
  if (!got_frame_ptr) {
  
      qWarning("no frame could be decompressed: %s %d/%d", av_err2str(ret), d.undecoded_size, packet.data.size());
  
      return !packet.isEOF();
  
  }

  When i run it I get an error (I go inside if(!got_frame_ptr) ) and in the printing i get that ret value’s is :
  203,3053,5120
  (or more accurate tis is my printings :

  Warning: "no frame could be decompressed: Error number 203 occurred 0/203"
Warning: "no frame could be decompressed: Error number 3053 occurred 0/3053"
Warning: "no frame could be decompressed: Error number 5120 occurred 0/5120"

  (av_err2str(ret) just print decorated ret, nothing more))

  the avcodec_decode_video2 docomentatin said :
  On error a negative value is returned, otherwise the number of bytes used or zero if no frame could be decompressed.

  i’m not in situation that avcodec_decode_video2 return me negative value, but i do get zero at got_frame_ptr , instead of got_frame_ptr will be the same value as ret like doc. said i get this odd value (203,3053,5120).

  my questions is :

  1. what this error code means ? (i search at ffmpeg doc. and i didn’t found a good record on what every numeric value should represent)

  2. why i get this values from this function ? is it ffmpeg bug ? or did i didn’t understand ffmpeg currectly ?

  thank you
  g.

• Live streaming dash content using mp4box

  15 mai 2017, par galbarm

  I’m trying to live stream H.264 content to HTML5 using the media source extensions API.

  The following method works pretty well :

  ffmpeg -i rtsp://10.50.1.29/media/video1 -vcodec copy -f mp4 -reset_timestamps 1 -movflags frag_keyframe+empty_moov -loglevel quiet out.mp4

  and then :
  mp4box -dash 1000 -frag 1000 -frag-rap out.mp4

  I can take the MP4Box output (out_dashinit.mp4) and send it through Web Sockets, chunk by chunk, to a JavaScript client that feeds it to the media source API.

  However, this is not a good method for live content.

  What I’m trying to do now, is to create a single pipeline in order to do it in realtime and with the minimum possible latency.
  With FFmpeg it’s possible to redirect the output to stdout instead of out.mp4 and grab the content.
  I couldn’t figure out if it’s possible to combine MP4Box into the pipeline.

  1. Can MP4Box take the input data from a source which is not a file ?
  2. Can MP4Box grab such a content progressively (either from a file or other source) while it is arriving in realtime ? i.e. wait a little if stream stops for 1 sec and resume automatically.
  3. Same question but for the output : can it output to something which is not a file (such as stdout) and can it do so progressively so that whenever output data is ready, I will be able to take it and transfer it to the web client, essentially generating a never-ending dashed MP4.

• avcodec/utils : Only call codec->close if init has been called

  24 septembre 2020, par Andreas Rheinhardt

  avcodec/utils : Only call codec->close if init has been called
  avcodec_open2() also called the AVCodec's close function if an error
  
  happened before init had ever been called if the AVCodec has the
  
  FF_CODEC_CAP_INIT_CLEANUP flag set. This is against the documentation of
  
  said flag : "The codec allows calling the close function for deallocation
  
  even if the init function returned a failure."
  E.g. the SVQ3 decoder is not ready to be closed if init has never been
  
  called.
  Fixes : NULL dereference
  
  Fixes : 25762/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_SVQ3_fuzzer-5716279070294016
  Found-by : continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
  Reviewed-by : Paul B Mahol <onemda@gmail.com>
  
  Reviewed-by : Michael Niedermayer <michael@niedermayer.cc>
  
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavcodec/utils.c