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• FFMpeg - Video conversion - .OGG to .MP4

  21 septembre 2018, par Hue Man

  After scouring the net, I can’t find anyone else trying to do this :
  Convert an OGG video format to MP4 video (usualy people are doing this the other way round).
  I have FFMpeg working just fine converting WEBM to MP4 but it just doesn’t seem to like OGG files.
  The official FFMpeg documentation says that it can both Encode AND Decode OGG files but for some reason it isn’t.
  Any ideas ?

• Ffmpeg decode H264 video from RTP stream very slow

  3 octobre 2013, par Dmitry Bakhtiyarov

  I have H264 RTP stream over network and I need to decode it. I use libx264 to encode stream and ffmpeg to decode. When I connect to server using VLC, it correct play video without any problem. But when I connect to server using my application I have a long period, when widget, which draw video from this stream, draw only one image.

  I check log file and found, that avcodec_decode_video2() set got_image into 1 very rarely ! Decoder give me new decoded frame average every 1-2 seconds, but on the server I have 12-15 fps on encoder !

  What the reasons of this delays on decoder and how I can fix its ?

  avcodec_register_all();
  
  av_init_packet(&m_packet);
  
  m_decoder = avcodec_find_decoder(CODEC_ID_H264);
  
  if (!m_decoder)
  
  {
  
      QString str = QString("Can't find H264 decoder!");
  
      emit criticalError(str);
  
  }
  
  m_decoderContext = avcodec_alloc_context3(m_decoder);
  
  
  
  m_decoderContext->flags |= CODEC_FLAG_LOW_DELAY;
  
  m_decoderContext->flags2 |= CODEC_FLAG2_CHUNKS;
  
  AVDictionary* dictionary = nullptr;
  
  if (avcodec_open2(m_decoderContext, m_decoder, &dictionary) < 0)
  
  {
  
      QString str = QString("Failed to open decoder!");
  
      emit criticalError(str);
  
  }
  
  qDebug() << "H264 Decoder successfully opened";
  
  m_picture = avcodec_alloc_frame();
  
  ...
  
      while(m_packet.size > 0)
  
      {
  
          int got_picture;
  
          int len = avcodec_decode_video2(m_decoderContext, m_picture, &got_picture, &m_packet);
  
          if (len < 0)
  
          {
  
              QString err("Decoding error");
  
              qDebug() << err;
  
              //emit criticalError(err);
  
              return false;
  
          }
  
          if (got_picture)
  
          {
  
                  //create from frame QImage and send it into GUI thread
  
              qDebug() << "H264Decoder: frame decoded!";

  I try to change some options of m_decoderContext (i.e. thread_count) but this not changing anything.

• ffmpeg drawtext RGB color codes

  19 janvier 2018, par Manish Jha

  I have an ffmpeg command which overlays an image and some text on a video where arguments are :

   -i "C:\exports\blue.mp4"
  
   -i "D:\Manish\Videos\logo.png" 
  
   -filter_complex 
  
   "[0:v]drawtext=fontfile='C\:\\Windows\\Fonts\\arial.ttf':
  
    text='falana dhimaka':
  
    fontcolor=AntiqueWhite:
  
    fontsize=20:x=1000:y=10[text]; 
  
    [text][1:v]overlay=140:5[filtered]" -map "[filtered]" -map 0:a? -codec:a copy 
  
    -preset ultrafast -ac 2 "C:\exports\blue_wm.mp4"

  This works well, but I want to be able to supply RGB Hex instead of AntiqueWhite. Any help is appreciated.