Ok solved the problem by myself:

Qt Code: 
  1. void MainWindow::try_with_ffmpeg()
  2. {
  3.     av_register_all();
  4.  
  5.     int             audioStream = -1;
  6.     AVCodecContext  *codecContext;
  7.     AVCodec         *codec;
  8.     AVPacket        packet;
  9.  
  10.     av_open_input_file(&formatContext, WMV, NULL,0,NULL);
  11.     av_find_stream_info(formatContext);
  12.     av_dump_format(formatContext, 0, WMV,0);
  13.  
  14.     for( unsigned int i=0; i < formatContext->nb_streams; i++ )
  15.     {
  16.         if( formatContext->streams[i]->codec->codec_type == CODEC_TYPE_AUDIO )
  17.         {
  18.             audioStream = i;
  19.             break;
  20.         }
  21.     }
  22.     if( audioStream == -1 )
  23.     {
  24.         qWarning() << "Didnt find audio stream";
  25.         return;
  26.     }
  27.  
  28.     codecContext = formatContext->streams[audioStream]->codec;
  29.  
  30.     codec = avcodec_find_decoder(codecContext->codec_id);
  31.     avcodec_open(codecContext,codec);
  32.  
  33.     med_buffer = (uint8_t*)malloc(AVCODEC_MAX_AUDIO_FRAME_SIZE + FF_INPUT_BUFFER_PADDING_SIZE);
  34.     buffer.open(QBuffer::WriteOnly);
  35.  
  36.     while( av_read_frame(formatContext,&packet) >= 0 )
  37.     {
  38.         qint64 written=0;
  39.         if( packet.stream_index == audioStream )
  40.         {
  41.             qDebug() << "size= " << packet.size;
  42.             while(packet.size > 0)
  43.             {
  44.                 int len, data_size = AVCODEC_MAX_AUDIO_FRAME_SIZE;
  45.                 //decode
  46.                 len = avcodec_decode_audio3(codecContext, (int16_t*)med_buffer, &data_size, &packet);
  47.                 if( len <= 0 )
  48.                     qWarning() << "no data read to buffer";
  49.                 if( data_size > 0 )
  50.                     written = buffer.write((const char*)med_buffer, data_size);
  51.  
  52.                 packet.size -= len;
  53.                 packet.data += len;
  54.  
  55.                 if( buffer.size() > 10000000 )
  56.                 {
  57.                     qDebug() << "buffer.size()=" << buffer.size();
  58.                     break;
  59.                 }
  60.             }
  61.  
  62.         }
  63.  
  64.     }
  65.  
  66.     QAudioFormat format;
  67.     format.setFrequency(codecContext->sample_rate);
  68.     format.setChannels(2);
  69.     format.setSampleSize(16);
  70.     format.setCodec("audio/pcm");
  71.     format.setByteOrder(QAudioFormat::LittleEndian);
  72.     format.setSampleType(QAudioFormat::SignedInt);
  73.  
  74.     QAudioDeviceInfo info(QAudioDeviceInfo::defaultOutputDevice());
  75.  
  76.     if (!info.isFormatSupported(format)) {
  77.         qWarning()<<"raw audio format not supported by backend, cannot play audio.";
  78.         format = info.nearestFormat(format);
  79.     }
  80.  
  81.     audio = new QAudioOutput(format, this);
  82.  
  83.     connect(audio,SIGNAL(stateChanged(QAudio::State)),SLOT(stateChanged(QAudio::State)));
  84.  
  85.     if( !buffer.open(QBuffer::ReadWrite) )
  86.         qWarning() << "Couldnt open Buffer";
  87.  
  88.     qDebug() << "buffer.size()=" << buffer.size();
  89.  
  90.     audio->start(&buffer);
  91. }
To copy to clipboard, switch view to plain text mode