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• FFMpeg(Android) av_read_frame or avcodec_decode_video2 returning same colour

  5 décembre 2012, par Cehm

  I've been experimenting FFMpeg for the past 2 weeks and I'm having a bit of trouble...
  First I've been working with a Galaxy S3, which worked super fine, gave me the best pictures ever but I recently switched to a Galaxy NEXUS which gave me a bunch of problems...

  What I'm doing : I just extract frame from a video

  How I'm doing :

  while(av_read_frame(gFormatCtx, &packet)>=0)
  
          {
  
              // Is this a packet from the video stream?
  
              if(packet.stream_index==videoStream)
  
              {
  
                  // Decode video frame
  
                  avcodec_decode_video2(gVideoCodecCtx, pFrame, &frameFinished, &packet);
  
                  // Did we get a video frame?
  
                  if(frameFinished)
  
                  {//and so on... But our problem is already here...

  Ok, now pFrame is holding a YUV representation of my frame... So, in order to check what I'm getting from the avcodec_decode_video2(...) function I'm just writing pFrame to a file so I can see it with any YUV reader on the web.

  char yuvFileName[100];
  
  sprintf(yuvFileName,"/storage/sdcard0/yuv%d.yuv",index);
  
  FILE* fp = fopen(yuvFileName, "wb");
  
  int y;
  
  // Write pixel data
  
  for(y=0; yheight; y++)
  
  {
  
      fwrite(pFrame->data[0]+y*pFrame->linesize[0], 1, gVideoCodecCtx->width, fp);    
  
  }
  
  for(y=0; yheight/2; y++)
  
  {
  
      fwrite(pFrame->data[1]+y*pFrame->linesize[1], 1, gVideoCodecCtx->width/2, fp);
  
  }
  
  for(y=0; yheight/2; y++)
  
  {
  
      fwrite(pFrame->data[2]+y*pFrame->linesize[2], 1, gVideoCodecCtx->width/2, fp);
  
  }
  
  fclose(fp);

  Ok so Here I now have my result on a file store @ /storage/sdcard0/blabla.YUV on my Galaxy Nexus root memory.

  But If I open the file with (for example XnView, which is meant to display YUV type properly) I only see Dark green on the picture.

  What bothers me is that everything worked properly on Galaxy S3 but something failed on GNexus...

  So here's my question : Why doesn't it work on Galaxy Nexus ?

  Compatibility problem between Gnexus and armeabiv7 ?

  I don't know !

  Regards,
  Cehm

• Contrast normalization of several videos with ffmpeg

  4 octobre 2016, par Alan_AI

  I have some video sequences that I need to concatenate, some of them have bad contrast (so dark) and some are just fine. What is the best method to automatically normalize contrast levels among of these videos automatically without manual tweaking ? Preferably using the ffmpeg script

  Thank you

• Erreur dans squelette collection

  
  2 décembre 2013

  Slt,

  Erreur dans squelette collection à http://cyc.mediaspip.net/collection/saint-malo-event-youth-workers?id_media=417#media_417
  « Aucun squelette breadcrumb/collection n’est disponible... »

  N’apparait que quand connecté

  ++
  Pierre-Yves