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• avfilter/trim : add compatibility layer to not break ABI used by ffmpeg

  12 juillet 2013, par Michael Niedermayer

  avfilter/trim : add compatibility layer to not break ABI used by ffmpeg
  This is a hotfix to fix -t / -ss
  
  a different solution might be choosen later, i just dont want to leave
  
  this broken
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavfilter/trim.c

• How to prevent overwriting fifo while playing local file with ffmpeg ?

  21 juillet 2013, par frankish

  I use av_read_frame() to read and push frames to fifo. In another thread, I read from this fifo. So, reading and writing does not interfere that much.

  However, I found out that when playing from a local file, audio suddenly skips to somewhere else.. I tried to open recorded file with VLC player and it worked. So the file(recording) is not broken.

  I tried (just to see if it works) the following and it works but it has other problems.

  ...
  
  if(localFile){
  
      while(av_fifo_size(fifoPlayback)>2000000){
  
          pthread_mutex_unlock(&fifoPlaybackMutex);
  
          usleep(1000000);
  
          pthread_mutex_lock(&fifoPlaybackMutex);
  
          // Waiting before writing to fifo, it's not empty enough");
  
      }
  
  }
  
  
  
  av_fifo_generic_write(fifoPlayback,...)

  Since the above block at least does not skip, I think my problem is really overwriting on the fifo. But how should I correctly manage this situation ?

• How to detect Audio or Video or Both exist in converted file

  28 juillet 2016, par Khaja Hussain

  I am trying to convert mp4 or 3gp video files into Flash (flv) format (using Perl script), using following (mencoder) command :

  mencoder test.mp4 -of lavf -ovc lavc -lavcopts vcodec=flv:vbitrate=1000:mbd=2 -fps 20.80 -ofps 20.80 -oac mp3lame -lameopts abr:br=32 -srate 22050 -o test.flv

  It works fine, but some files which comes as attachments from mobile phone has problem, the converted FLV file has only audio.

  I also used ffmpeg command as follows :

  ffmpeg -i test.mp4 -ar 22050 -acodec libmp3lame -ab 32K -r 25 -vcodec flv test.flv

  This ffmpeg command helps to convert to flv, which is failed by mencoder.

  I am thinking some solution like, need to check whether converted flv has audio and video then will take action depends on it. Could you help me to solve this issue ?

  Here is some more info (log) :

  [mov,mp4,m4a,3gp,3g2,mj2 @ 0xb6b9a3a0]multiple edit list entries, a/v desync might occur, patch welcome
  ** MUXER_LAVF *************************************
  REMEMBER : MEncoder’s libavformat muxing is presently broken and can generate
  INCORRECT files in the presence of B-frames. Moreover, due to bugs MPlayer
  will play these INCORRECT files as if nothing were wrong !

  ---

  Unsupported PixelFormat 61
  Unsupported PixelFormat 53
  Unsupported PixelFormat 81
  [flv @ 0xb6b9a3a0]Codec for stream 0 does not use global headers but container format requires global headers
  [flv @ 0xb6b9a3a0]Codec for stream 1 does not use global headers but container format requires global headers
  [flv @ 0xb6b9a3a0]pts < dts in stream 0
  Error while writing frame.

  [flv @ 0xb6b9a3a0]pts < dts in stream 0
  Error while writing frame.

  [flv @ 0xb6b9a3a0]pts < dts in stream 0
  Error while writing frame.

  [flv @ 0xb6b9a3a0]pts < dts in stream 0
  Error while writing frame.

  [flv @ 0xb6b9a3a0]pts < dts in stream 0
  Error while writing frame.

  Skipping frame !

  .........................