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• Libavformat- Passing an object of images to libavformat to generate a video

  8 septembre 2020, par Venkata Tata

  I am trying to generate a video with libavformat/Libavcodec with a bunch of images that are in memory.

  


  Can someone point me in the right direction, please ?

  


  Thanks in advance.

  


• Peer to peer video chat ? [closed]

  30 mars 2013, par aladein

  I want to program a peer to peer video chat application. can any body suggest an open source real time video codec with low latency. I prefer to work with c#.
  ffmpeg is great but I could not figure how to use (stream over
  network) it on windows.
  thank you in advance.

• Generating synthetic testsrc video counting at 10 fps, first frame is duplicated

  19 février 2020, par Rotem

  I am trying to generate synthetic video using FFmpeg.

  I want the frame rate to be 10 fps, and I want testsrc counter to advance every frame.

  Problem :
  When the output file is mp4, the first video frame is duplicated 10 times.

  Question :
  Is it a bug in FFmpeg, or a problem in the command line arguments ?

  ---

  I am using the following command :

  ffmpeg -y -r 10 -f lavfi -i testsrc=duration=10:size=192x108:rate=1 -c:v libx264 vid.mp4

  • The reason for setting rate=1 is for the counter to advance on each frame.
    The generated source pattern is designed to advance the counter every second.
  • The reason for setting -r 10 before the input, is for "remuxing" the video at 10 fps, and ignoring the timestamps of the input.

  I found the syntax in the following post : Using ffmpeg to change framerate :

  Remux with new framerate

  ffmpeg -y -r 24 -i seeing_noaudio.h264 -c copy seeing.mp4

  When the output file is AVI it’s working correctly (first frame is not duplicated) :

  ffmpeg -y -r 10 -f lavfi -i testsrc=duration=10:size=192x108:rate=1 -c:v libx264 vid.avi

  When generating AVI at 1 fps, and Remux to mp4 at 10 fps, there is a different problem :
  The first and second frames are duplicated twice, and the last frame is missing.
  Here are the commands :

  ffmpeg -y -f lavfi -i testsrc=duration=10:size=92x54:rate=1 -c:v libx264 -r 1 vid.avi
  
  ffmpeg -y -r 10 -i vid.avi -c:v copy -r 10 vid.mp4

  ---

  Parsing the mp4 video to PNG images :

  ffmpeg -i vid.mp4 %02d.png  

  Result :
  
  The first frame is duplicated 10 times.

  ---

  Parsing the AVI video to PNG images :
  Result :
  
  There are 10 frames as expected.