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• ffmpeg is dropping frames of second video in concat

  17 juin 2018, par bugwheels94

  I did a screen share and when sharing the screen I minimized the sharing window so the video that I am sharing has some thing weird going on. Seeking does not work on mplayer but works on VLC. However, when doing the concat

  ffmpeg -i test.webm -f lavfi -i color=c=blue:s=1366x768:d=71 \
  
  -filter_complex "[0]scale=w='min(1366\, iw)':h='min(768\, ih)':force_original_aspect_ratio=decrease,\
  
  pad=width=1366:height=768:x=(ow-iw)/2:y=(oh-ih)/2,setsar=1/1[v1];\
  
  [1][v1]concat=n=2[v]" -map [v] -qscale 7 result.mp4

  The webm video of length 155 seconds is not showing complete. Ideally the result should be 71 + 156 = 227 but I am getting 155 seconds and the webm video of concat being cropped.

  If I reverse the concat order to [v1][1]concat=n=2[v] then everything is perfect at 227 seconds

  Download test.webm

  May you please tell me about what might be wrong here ? Thanks

• 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.