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• (FFMPEG) avformat_write_header crashes (MSVC2013) (C++) (Qt)

  29 avril 2015, par user3502626

  I just downloaded FFMPEG and now I’m trying to use it in Qt with MSVC2013 compiler.

  To understand how it works, I started reading the documentation and the API.
  According to this figure, I was trying to make a little test with libavformat.

  I did all they said in the demuxing module, then the muxing module. But, my program crashes when I call the avformat_write_header() function.

  I would like to know what I did wrong and if you could help me to understand that.

  In the main :

  av_register_all();
  
  
  
  if(!decode())
  
      return;

  The decode() methode :

  bool MainWindow::decode()
  
  {
  
  AVFormatContext *formatContext = NULL;
  
  AVPacket packet;
  
  
  
  /**************** muxing varaiables ******************/
  
  
  
  AVFormatContext *muxingContext = avformat_alloc_context();
  
  AVOutputFormat *outputFormat = NULL;
  
  AVIOContext *contextIO = NULL;
  
  AVCodec *codecEncode = avcodec_find_encoder(AV_CODEC_ID_WMAV2);
  
  AVStream *avStream =  NULL;
  
  AVCodecContext *codecContext = NULL;
  
  
  
  
  
  /******************* demuxing **************************/
  
  
  
  //open a media file
  
  if(avformat_open_input(&formatContext,"h.mp3",NULL,NULL)!=0)
  
  {
  
      qDebug() << "paka ouve fichier";
  
      return false;
  
  }
  
  
  
  //function which tries to read and decode a few frames to find missing          
  
  information.
  
  if(avformat_find_stream_info(formatContext,NULL)<0)
  
  {
  
      qDebug()<<"paka find stream";
  
      return false;
  
  }
  
  
  
  
  
  /**************** muxing *************************/
  
  
  
  //The oformat field must be set to select the muxer that will be used.
  
  muxingContext->oformat = outputFormat;
  
  
  
  //Unless the format is of the AVFMT_NOFILE type, the pb field must be set to
  
  //an opened IO context, either returned from avio_open2() or a custom one.
  
  if(avio_open2(&contextIO,"out.wma",AVIO_FLAG_WRITE,NULL,NULL)<0)
  
  {
  
      qDebug() <<"paka kreye fichier soti";
  
      return false;
  
  }
  
  muxingContext->pb = contextIO;
  
  
  
  //Unless the format is of the AVFMT_NOSTREAMS type, at least
  
  //one stream must be created with the avformat_new_stream() function.
  
  avStream = avformat_new_stream(muxingContext,codecEncode);
  
  
  
  //The caller should fill the stream codec context information,
  
  //such as the codec type, id and other parameters
  
  //(e.g. width / height, the pixel or sample format, etc.) as known
  
  
  
  codecContext = avStream->codec;
  
  codecContext->codec_type = AVMEDIA_TYPE_AUDIO;
  
  codecContext->codec_id = AV_CODEC_ID_WMAV2;
  
  codecContext->sample_fmt = codecEncode->sample_fmts[0];
  
  codecContext->bit_rate = 128000;
  
  codecContext->sample_rate = 44000;
  
  codecContext->channels = 2;
  
  
  
  //The stream timebase should be set to the timebase that the caller desires
  
  //to use for this stream (note that the timebase actually used by the muxer
  
  //can be different, as will be described later).
  
  
  
  avStream->time_base = formatContext->streams[0]->time_base;
  
  qDebug()<streams[0]->time_base.num <<"/" 
  
  <streams[0]->time_base.den;
  
  
  
  
  
  //When the muxing context is fully set up, the caller must call     
  
  //avformat_write_header()
  
  //to initialize the muxer internals and write the file header
  
  
  
  qDebug() << "does not crash yet";
  
  if(avformat_write_header(muxingContext,NULL) <0)
  
  {
  
      qDebug()<<"cannot write header";
  
      return false;
  
  }
  
  qDebug() << "OOps you can't see me (John Cena)";
  
  
  
  ///////////////////// Reading from an opened file //////////////////////////
  
  while(av_read_frame(formatContext,&packet)==0)
  
  {
  
      //The data is then sent to the muxer by repeatedly calling
  
      //av_write_frame() or av_interleaved_write_frame()
  
      if(av_write_frame(muxingContext,&packet)<0)
  
          qDebug()<<"paka write frame";
  
      else
  
          qDebug()<<"writing";
  
  }
  
  
  
  //Once all the data has been written, the caller must call
  
  //av_write_trailer() to flush any buffered packets and finalize
  
  //the output file, then close the IO context (if any) and finally
  
  //free the muxing context with avformat_free_context().
  
  
  
  if(av_write_trailer(muxingContext)!=0)
  
  {
  
      qDebug()<<"paka ekri trailer";
  
      return false;
  
  }
  
  
  
  
  
  return true;
  
  }

  The program shows the message does not crash yet. But not OOps you can’t see me (John Cena)

  And there is no error. I used an MP3 file as input and I would like to ouput it in WMA.

• cmdutils : replace usages of "#ifdef __MINGW32__" with "#ifdef _WIN32" because MSVC...

  17 mai 2014, par John Peebles

  cmdutils : replace usages of "#ifdef __MINGW32__" with "#ifdef _WIN32" because MSVC only defines _WIN32
  With the previous patch, this should fix ticket #3580 as well.
  Signed-off-by : John Peebles <johnpeeb@gmail.com>
  

  • [DH] cmdutils.h
  • [DH] ffplay.c

• libavformat : output cues for each subtitle block in MKV muxer

  22 mai 2014, par John Peebles

  libavformat : output cues for each subtitle block in MKV muxer
  Signed-off-by : John Peebles <johnpeeb@gmail.com>
  
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] MAINTAINERS
  • [DH] libavformat/matroskaenc.c