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• FFmpeg : Frame sizes of the generated video are extremely larger than the expected [closed]

  8 février 2021, par bbasaran

  I am recording frames (screen buffer) as NumPy arrays during the game which runs on the resolution of "400x225". Each frame array is a size of 270.1 kB.

  


  After saving those frames, I create an mp4 file with the following bash command (The game runs in 35 FPS (frames/second)) :

  


  ffmpeg -r 35 -f image2 -i frame%05d.png -vcodec libx264 -crf 1 video.mp4


  


  Then I have used a tool to generate a CSV file of frame data from the video created with the command above. The output is here below. The weird this is that, if we sum those first 35 frames (video was recorded with "-r 35" parameter because game runs in 35 FPS), we get approximately 18k kbit.

  


  18k kbit/sec bitrate is super high for a 400x225 video. What am I doing wrong while generating the video ? I appreciate any help, thanks !

  


  

  


• ffmpeg read from a file and apply filter_complex at once

  30 janvier 2020, par AlexZheda

  I am feeding fls.txt into ffmpeg -i and applying concat and a speedup.

  fls.txt

  file 'input1.mp4'
  
  file 'input2.mp4'
  
  file 'input3.mp4'

  The command in one go looks as follows :

  ffmpeg  -i fls.txt     \
  
  -filter_complex "[0:v][0:a][1:v][1:a][2:v][2:a] concat=n=3:v=1:a=1 [v][a];\
  
  [v]setpts=0.5*PTS[v1];[a]atempo=2,asetpts=N/SR/TB[a1]"     \
  
  -c:v h264_nvenc -map "[v1]" -map "[a1]"  x2.mp4

  The output is really weird and says something like a stream is not found. And it also looks like as if it’s trying to understand the fls.txt itself and not its content as the parameters.
  What am I doing wrong here and how can I correct it ?
  Also, it’s a simplified example and I cannot write per hand 3 input file paths. I need it to be read from a file. I’m on windows 10 if that matters.

  EDIT :
  From doing the suggested edits and expanding the -filter_complex I get an error below.

  ffmpeg -f concat -safe 0 -i fls.txt     \
  
  -filter_complex "[0:v]setpts=0.5*PTS[v1];[v1]setpts=0.5*PTS[v2];[0:a]atempo=2,asetpts=N/SR/TB[a1];[a1]atempo=2,asetpts=N/SR/TB[a2]"     \
  
  -c:v h264_nvenc -map "[v1]" -map "[a1]" x2.mp4 \
  
  -c:v h264_nvenc -map "[v2]" -map "[a2]" x4.mp4

  error :

  Output with label 'v1' does not exist in any defined filter graph, or was already used elsewhere.

• avdevice/decklink_enc : fix setting of last_pts to only be set for video

  3 mars 2023, par Devin Heitmueller

  avdevice/decklink_enc : fix setting of last_pts to only be set for video
  The ff_decklink_write_packet() was always caching the last pts
  
  received, to be used when calling StopScheduledPlayback(). However
  
  because audio and video are on different timebases and the call to
  
  StopScheduledPlayback() expects the video timebase, we'll end up
  
  sending a weird value to the stop routine if the last packet
  
  received contained audio.
  Move the setting of last_pts to just be for the video stream.
  Signed-off-by : Devin Heitmueller <dheitmueller@ltnglobal.com>
  
  Signed-off-by : Marton Balint <cus@passwd.hu>
  

  • [DH] libavdevice/decklink_enc.cpp