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• How to handle unstable fps with FFMPEG ?

  16 décembre 2022, par Berkay

  I'm running an object detection pipeline in python using yoloV5. It's basically a project that reads frames from an RTSP camera and runs inference on them. I'm also recording short videos for every detection. My problem is that FPS slightly varies every now on then.
My question is that, how can I stabilize the fps for a given video ? We give the input fps once at the process creation and then it stays the same. However for the rest of the code it fluctuates.
Is there a method that can compensate for small changes ?

  


  I'm using the following snippet to record my videos :

  


    ffmpeg_processes[video_id] = (Popen(['ffmpeg', '-y', '-f', 'image2pipe',
                                                             '-vcodec', 'mjpeg', '-r', str(fps),
                                                             '-i', '-', '-vcodec', 'libx264', '-qscale',
                                                             '5', '-r', str(fps), video_path],


  


  I keep a video_id for each detection and add them frames until the desired duration is reached.
then I add the frames in the following way :

  


          for vid_id, value in ffmpeg_processes.items():
            process, num_of_frames, fps = value
            if num_of_frames < DETECTION_VIDEO_LENGTH * fps:
                frame_to_save.save(process.stdin, 'JPEG')
                ffmpeg_processes[vid_id] = (process, num_of_frames + 1, fps)


  


  Although the duration is exactly what I wanted ,let's say 10 secs, the video recorded actually is 12 seconds in real time. I think this is due to the slight variations of the rest of the pipeline (1-2 fps changes).

  


• avcodec/pnm_parser : Use memmove() to handle "overread"

  1er août 2019, par Michael Niedermayer

  avcodec/pnm_parser : Use memmove() to handle "overread"
  This is significantly faster
  Fixes : Timeout (1sec after this and the previous commit)
  
  Fixes : 15558/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_PPM_fuzzer-5705273643106304
  Found-by : continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/pnm_parser.c

• build : handle library dependencies in configure

  1er mai 2014, par Janne Grunau

  build : handle library dependencies in configure
  Instead of setting FFLIBS in each library Makefile configure
  
  exports FFLIBS-$library in config.mak.
  

  • [DBH] common.mak
  • [DBH] configure
  • [DBH] libavcodec/Makefile
  • [DBH] libavdevice/Makefile
  • [DBH] libavfilter/Makefile
  • [DBH] libavformat/Makefile
  • [DBH] libavresample/Makefile
  • [DBH] libswscale/Makefile