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• How to prevent my users from installing ffmpeg themselves

  7 février 2018, par keys king

  I would like to develop a program for converting video formats based on the ffmpeg command line on mac. I should use c ++ or python. But now there is a problem that bothers me. I do not want my users to have to install the ffmpeg command themselves , before I use my program, so what should I do ? My question may be naive, I’m just a sophomore in college and I would be very grateful if you could help me.

  I should check whether there is ffmpeg in the program, and then use the command line to install it ? I hope my program can bring ffmpeg, rather than to install

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  Sorry, I did not say clearly. I hope my program can be the same as the normal mac program can be placed directly into the Application folder. And then you can open directly. I will use qt to draw the interface

• 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();
  
  }

• Consume RTSP stream from users browser without converting on the server

  19 août 2018, par Kazanz

  I have thousands of IP cameras that need to be displayed to various users that are all outputing RTSP streams. Right now I have a server that uses ffpmeg to convert the stream to mpeg video that is then consumed and served over websockets via a node app.

  My problem is that these two processes take up a ridiculous amount of memory. About a half a GB for each camera.

  Is there any way to offload the conversion and reading of the stream to the client’s machine in their browser, or potentially out of it ?