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• Is there any control property to fix video playback speed problem when using ffmpeg to decode in Qt platform ?

  16 février 2019, par SoloWang

  I want to play local video file in Qt platform using ffmpeg to decode.Everything is OK except that play speed is as twice as normal.
  The first thing I think about is that there must be a sampling frequency involved.But to be a new to ffmpeg,I don’t know how to fix this problem.
  Above is my code to read frame,is anyone can tell me what’s wrong with the code ?

  void VideoThread::run()
  
  {
  
      m_pInFmtCtx = avformat_alloc_context(); //ini struct
  
      char path[] = "d:/test.mp4";
  
      // open specific file
  
      if(avformat_open_input(&m_pInFmtCtx, *path, NULL, NULL)){ 
  
      {
  
          qDebug()<<"get rtsp failed";
  
          return;
  
      }
  
      else
  
      {
  
          qDebug()<<"get rtsp success";
  
      }
  
  
  
  
  
      if(avformat_find_stream_info(m_pInFmtCtx, NULL) < 0)
  
      {
  
          qDebug()<<"could not find stream information";
  
          return;
  
      }
  
      int nVideoIndex = -1;
  
      for(int i = 0; i < m_pInFmtCtx->nb_streams; i++)
  
      {
  
          if(m_pInFmtCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
  
          {
  
              nVideoIndex = i;
  
              break;
  
          }
  
      }
  
      if(nVideoIndex == -1)
  
      {
  
          qDebug()<<"could not find video stream";
  
          return;
  
      }
  
  
  
      qDebug("---------------- File Information ---------------");
  
      m_pCodecCtx = m_pInFmtCtx->streams[nVideoIndex]->codec;
  
      m_pCodec = avcodec_find_decoder(m_pCodecCtx->codec_id);
  
      if(!m_pCodec)
  
      {
  
          qDebug()<<"could not find codec";
  
          return;
  
      }
  
      //start Decoder
  
      if (avcodec_open2(m_pCodecCtx, m_pCodec, NULL) < 0) {
  
          qDebug("Could not open codec.\n");
  
          return;
  
      }
  
  
  
  
  
      //malloc space for stroring frame
  
      m_pFrame     = av_frame_alloc();
  
      m_pFrameRGB  = av_frame_alloc();
  
      m_pOutBuf = (uint8_t*)av_malloc(avpicture_get_size(AV_PIX_FMT_RGB32, m_pCodecCtx->width, m_pCodecCtx->height));
  
      avpicture_fill((AVPicture*)m_pFrameRGB, m_pOutBuf, AV_PIX_FMT_RGB32, m_pCodecCtx->width, m_pCodecCtx->height);
  
  
  
      //for color switch,from YUV to RGB
  
      struct SwsContext *pImgCtx = sws_getContext(m_pCodecCtx->width, m_pCodecCtx->height, m_pCodecCtx->pix_fmt,
  
                                                  m_pCodecCtx->width, m_pCodecCtx->height, AV_PIX_FMT_RGB32, SWS_BICUBIC, NULL, NULL, NULL);
  
  
  
  
  
      int nSize = m_pCodecCtx->width * m_pCodecCtx->height;
  
      m_pPacket = (AVPacket *)av_malloc(sizeof(AVPacket));
  
      if(av_new_packet(m_pPacket, nSize) != 0)
  
      {
  
          qDebug()<<"new packet failed";
  
      }
  
  
  
      //isInterruptionRequested is a flag,determine whether the thread is over
  
      // read each frame from specific video file
  
      while (!isInterruptionRequested())
  
      {
  
          int nGotPic = 0;
  
          if(av_read_frame(m_pInFmtCtx, m_pPacket) >= 0)
  
          {
  
              if(m_pPacket->stream_index == nVideoIndex)
  
              {
  
                  //avcodec_decode_video2()transform from packet to frame
  
                  if(avcodec_decode_video2(m_pCodecCtx, m_pFrame, &nGotPic, m_pPacket) < 0)
  
                  {
  
                      qDebug()<<"decode failed";
  
                      return;
  
                  }
  
                  if(nGotPic)
  
                  {   // transform to RGB color
  
                      sws_scale(pImgCtx, (const uint8_t* const*)m_pFrame->data,
  
                                m_pFrame->linesize, 0, m_pCodecCtx->height, m_pFrameRGB->data,
  
                                m_pFrameRGB->linesize);
  
                      // save to QImage,for later use
  
                      QImage *pImage = new QImage((uchar*)m_pOutBuf, m_pCodecCtx->width, m_pCodecCtx->height, QImage::Format_RGB32);
  
                  }
  
  
  
              }
  
          }
  
  
  
          av_free_packet(m_pPacket);
  
          msleep(5);
  
      }
  
      exec();
  
  }

• avcodec/mips : [loongson] fix mpeg4 decoding error on loongson platform.

  24 mai 2019, par Shiyou Yin

  avcodec/mips : [loongson] fix mpeg4 decoding error on loongson platform.
  In function ff_dct_unquantize_mpeg2_intra_mmi,
  
  addr0 shoudn't be changed before storage operation.
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/mips/mpegvideo_mmi.c

• copy step written on stackoverflow to install FFMPEG on wamp not working

  17 septembre 2019, par user3833682

  I’m working on project for converting youtube videos into mp3 format and found this also to install ffmpeg on wamp server Install FFMPEG on WAMP and try other links also but ffmpeg extension is not installing so I also checked it at phpinfo to confirm its installed or not but not installed and I’ve windows 7 64, wampserver 2.4, apache 2.4.4 and php version is 5.4.12 I don’t know what am I missing, I spent my 6 hours to figure out but extension of ffmpeg is not installed yet please tell me what am I doing wrong ?

  Now after that I’m getting popup message twice when I start wamp server `PHP Startup : Unable to load dynamic library

  c :/wamp/bin/php/php5.4.12/ext/php_ffmpeg.dll’ - %1 is not a valid
  Win32 application.