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• Videos encoded with FFmpeg play too fast

  23 avril 2014, par Ari Black

  I’ve scoured the Google/SO/Zeranoe results and tried to integrate everything I found into making my program generate videos correctly but I still can’t get it to work right.

  I needed a good video to use as a reference so I ran :

  ffmpeg -t 5 -f dshow -i "video=Logitech HD Pro WebcamC910" CLI.mpg

  Which generated a five-second video which can be played in VLC and shows the duration and plays correctly. You can get the video here : https://drive.google.com/file/d/0B1VGi1Ts7D7TR3c4VUlyM2dIcFk/edit?usp=sharing

  I then generated a five-second video with my own code. I’ve tried to pare it down to only what I think is needed to record. You can find the code here : https://drive.google.com/file/d/0B1VGi1Ts7D7TMnFxSE1HX2FKbEU/edit?usp=sharing

  It generated a video also, with similar video quality, but VLC doesn’t show the video duration and the video seems to play too quickly. I mean that what I see on the screen looks like it’s moving slightly too fast. You can find the video my code generated here : https://drive.google.com/file/d/0B1VGi1Ts7D7TSzFGUFZEMHJwQ0U/edit?usp=sharing

  Even when you click on the links to the videos, you can see that Google is having trouble with mine but no problem with the one generated by the FFmpeg CLI. Sorry about posting everything off-site but I didn’t want to spam my code into the post and I wanted to provide as much information as I could.

  I’ve seen a number of posts about this but I can’t seem to find a definitive solution.

  EDIT :
  So I implemented your suggestions and I’m pretty sure that your answer fixed the timing issue but now I consistently get 20 non-strictly-monotonic errors before the first successful call encode_video. This happens whether I use

  gFrame->pts = gFrameIndex;

  or

  gFrame->pts = av_rescale_q(gFrameIndex, gCodecContext->time_base, gStream->codec->time_base);

  before

  ret = avcodec_encode_video2(gCodecContext, &pkt, gFrame, &got_output);
  
  if (ret < 0) {
  
    fprintf(stderr, "Error encoding frame\n");
  
    return false;
  
  }

  This seems to coincide with video artifacts at the start of the video file during playback. gFrameIndex starts at 1.

  I believe my webcam auto-focuses at the start of recordings, is it possible this is related ?

  I’ve uploaded the generated .h264 file at https://drive.google.com/file/d/0B1VGi1Ts7D7TRjRzbzZZemRaRTA/edit?usp=sharing and my most recent code to https://drive.google.com/file/d/0B1VGi1Ts7D7TbmlyYncxYzRQUTA/edit?usp=sharing.

  I really appreciate the help. Sadly, I can’t use the FFmpeg CLI directly in my software, so I have to use the library. I’m going to have to keep trucking along with it unless you can suggest a better alternative.

• Revision 17037 : report de r17030

  28 janvier 2011, par cedric -

  en SQLite sql_delete ne respectait pas encore le changement d’API introduit par r14495 : renvoyer le nombre de lignes supprimees ou false en cas d’echec. En renvoyant toujours true en cas de succes, meme si aucune ligne n’etait supprimee, la fonction trompait la gestion de la file d’attente de (...)

• Revision 17038 : report de r17030

  28 janvier 2011, par cedric -

  en SQLite sql_delete ne respectait pas encore le changement d’API introduit par r14495 : renvoyer le nombre de lignes supprimees ou false en cas d’echec. En renvoyant toujours true en cas de succes, meme si aucune ligne n’etait supprimee, la fonction trompait la gestion de la file d’attente de (...)