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• Detect if AVStream is broken

  9 juillet 2018, par Eugene Alexeev

  In my project I’m using an FFMpeg and I wrote a muxer which works with multi-video container (it’s an .mp4 with few video streams). And sometimes I have to deal with a situation when my code was fed up with file which has broken video stream. And the problem is - I need to find a way how I can detect broken stream and abandon it from usage.

  Here’s my code which I’m using for reading streams out of the file :

  - (BOOL)openFile:(NSString *)filePath options:(AVDictionary *)options
  
  {
  
      _pFormatCtx = NULL;
  
  
  
      if (avformat_open_input(&_pFormatCtx, [filePath UTF8String], NULL, &options) != 0) {
  
          [self raiseExceptionWithMessage:@"Couldn't open the file!"];
  
          return NO;
  
      }
  
  
  
      if (avformat_find_stream_info(_pFormatCtx, NULL) < 0) {
  
          //[self raiseExceptionWithMessage:@"Couldn't find stream info!"];
  
          return NO;
  
      }
  
  
  
      int stream_index = 0;
  
      for (int i = 0; i < _pFormatCtx->nb_streams ; i++)
  
      {
  
          AVStream *st = _pFormatCtx->streams[i];
  
          if (_pFormatCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO)
  
          {
  
              AVCodecParameters *params = st->codecpar;
  
              st->index = stream_index;
  
              _streams[@(st->index)] = [[VideoStream alloc] initWithStream:st];
  
              stream_index++;
  
          }
  
      }
  
  
  
      _firstStream = [_streams.allValues firstObject].stream;
  
  
  
      if (_streams.count == 0) {
  
          [self raiseExceptionWithMessage:@"Couldn't find videostream!"];
  
          return NO;
  
      }
  
  
  
      _pCodecParams = [self firstStream]->codecpar;
  
      _pCodec = avcodec_find_decoder(_pCodecParams->codec_id);
  
  
  
      if (!_pCodec) {
  
          [self raiseExceptionWithMessage:@"Unsupported codec!"];
  
          return NO;
  
      }
  
  
  
      _pCodecCtx = avcodec_alloc_context3(_pCodec);
  
      if (avcodec_parameters_to_context(_pCodecCtx, _pCodecParams) < 0) {
  
          [self raiseExceptionWithMessage:@"Couldn't copy params into codec"];
  
          return NO;
  
      }
  
  
  
      if (avcodec_open2(_pCodecCtx, _pCodec, 0) < 0) {
  
          [self raiseExceptionWithMessage:@"Couldn't open the Codec!"];
  
          return NO;
  
      }
  
  
  
      return YES;
  
  }

  When this method is opening video with broken video-stream, avformat_find_stream_info gives such output in logs :

  [h264 @ 0x10684e200] top block unavailable for requested intra mode -1
  
  [h264 @ 0x10684e200] error while decoding MB 45 0, bytestream 76665
  
  [h264 @ 0x10684e200] concealing 3600 DC, 3600 AC, 3600 MV errors in I frame
  
  [h264 @ 0x106854a00] top block unavailable for requested intra mode -1
  
  [h264 @ 0x106854a00] error while decoding MB 47 0, bytestream 69501
  
  [h264 @ 0x106854a00] concealing 3600 DC, 3600 AC, 3600 MV errors in I frame
  
  [h264 @ 0x10683de00] left block unavailable for requested intra4x4 mode -1
  
  [h264 @ 0x10683de00] error while decoding MB 0 1, bytestream 73290
  
  [h264 @ 0x10683de00] concealing 3600 DC, 3600 AC, 3600 MV errors in I frame
  
  [h264 @ 0x106860800] left block unavailable for requested intra4x4 mode -1
  
  [h264 @ 0x106860800] error while decoding MB 0 2, bytestream 23072
  
  [h264 @ 0x106860800] concealing 3559 DC, 3559 AC, 3559 MV errors in I frame

  Good news is avformat_find_stream_info clearly sees that something is wrong with the file. But bad news is - output of avformat_find_stream_info isn’t affected at all. After this method execution my AVFormatContext variable which is _pFormatCtx will have all streams file provides whether it’s valid or not.

  And my question - how can I differ bad stream from a good one ? What kind of data inside the stream I can rely on ? What kind of method I could use to test stream out ? Any help would be appreciated !

• How to swap package configuration for environment

  24 juillet 2018, par Finn Maunsell

  I’d like to change the location that I get ffmpeg from for my anaconda environment. The problem has occured because I want to use the ffmpeg configuration for my base system instead of the configuration meant for the environment.

  If I use ffmpeg in ubuntu bash then I get this for my active environment :

    ffmpeg version N-91510-gd134b8d Copyright (c) 2000-2018 the FFmpeg developers
  
    built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.10) 20160609
  
    configuration: --prefix=/home/notebook/ffmpeg_build --pkg-config-flags=--static --extra-cflags=-I/home/notebook/ffmpeg_build/include --extra-ldflags=-L/home/notebook/ffmpeg_build/lib --extra-libs='-lpthread -lm' --bindir=/home/notebook/bin --enable-gpl --enable-libaom --enable-openssl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-nonfree

  and for non-environment :

  ffmpeg version 3.4.1 Copyright (c) 2000-2017 the FFmpeg developers
  
    built with gcc 4.8.2 (GCC) 20140120 (Red Hat 4.8.2-15)
  
    configuration: --prefix=/home/notebook/anaconda2/envs/tensorflow --disable-doc --enable-shared --enable-static --extra-cflags='-Wall -g -m64 -pipe -O3 -march=x86-64 -fPIC -I/home/notebook/anaconda2/envs/tensorflow/include' --extra-cxxflags='=-Wall -g -m64 -pipe -O3 -march=x86-64 -fPIC' --extra-libs=
  
  '-L/home/notebook/anaconda2/envs/tensorflow/lib -lz' --enable-pic --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --enable-libx264

  Solving this will allow me to use the 2nd ffmpeg installation in my conda environment.

• Revision 50038 : Petites améliorations du formulaire de configuration On retrouve le ...

  28 juillet 2011, par kent1@… — Log

  Petites améliorations du formulaire de configuration
  On retrouve le logo pour CFG2
  Un peu de ménage dans les sites :
  Les éléments enlevés de la liste :
   Bluegger => fermé
   Furl => renvoit vers diigo.com
   Kirtsy => ne semble plus être un site de ce type
   Mixx => racheté et ne fonctionne plis
   pioche.fr => N’existe plus
   propeller.com => Racheté par aol news
   Shoutwire => semble avoir disparu de la toile
   ​http://simpy.com/ => semble avoir disparu de la toile
   ​http://www.tagtooga.com/ => semble avoir disparu de la toile
   twine => pointe vers evri.com => url à trouver ?
  Les éléments ajoutés :
   BarraPunto ? => ​http://barrapunto.com
   Bitacoras => ​http://bitacoras.com
   Dzone => ​http://www.dzone.com/
   Friendfeed => ​http://www.friendfeed.com
   identi.ca => ​http://identi.ca
   linkedin => ​http://www.linkedin.com
   Plaxo
  Petite modification de l’url de facebook
  On incrémente le numéro de version