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• ffmpeg : copy color properties in case of -c:v copy.

  3 mai 2016, par Ronald S. Bultje

  ffmpeg : copy color properties in case of -c:v copy.
  I have no idea why the first hunk uses ost->enc_ctx, because as far as
  
  I understand, that is never used in case of -c:v copy, but this code
  
  block is only entered if encoding_needed=0, which means stream_copy=1.
  
  My point being : review from someone that knows this really well would
  
  be appreciated.
  

  • [DH] ffmpeg.c

• FFMPEG : audio unsynchronized, losing framerate and strange behavior when pavucontrol is open

  10 mars 2021, par Rik Ferreira

  I'm trying to record my desktop screen with internal audio and mic, but I'm noticing some issues with the output, according to this empirical scale :

  


  

  • If I record only the desktop, the output is GOOD.

  


  • If I record the desktop + mic, the output is GOOD.

  


  • If I record the desktop + internal audio only, the output is BAD.

  


  • If I record the desktop + mic + internal audio, the output is BAD.

  


  • If I record the desktop + mic + internal audio + open pavucontrol, the output is GOOD.

  


  


  Good means the two audio sources and the video are acceptably synchronized and bad means not synchronized at all.

  


  I recorded some samples to show what is going on :

  


  

  • Screen + Mic + Internal audio

  


  • Screen + Mic

  


  • Screen + Mic + Internal audio + pavucontrol

  


  


  I'm snapping my fingers near the microphone when the Beep! message appears along with the sound.

  


  I'm using a simple script to play a sound and show a message in the terminal instead of using pavucontrol because it masks the problem.

  


  FFMPEG call

  


  Although the entire script is visible in the videos, here is the ffmpeg call in plain text :

  


  Dual audio

  


  ffmpeg -y \
    -f x11grab -s 1920x1080 -i :0.0 \
    -f pulse -i 0 \
    -f pulse -i 1 \
    -filter_complex amix=inputs=2 \
    output.mp4


  


  Only microphone

  


  ffmpeg -y \
    -f x11grab -s 1920x1080 -i :0.0 \
    -f pulse -i 1 \
    output.mp4


  


  Other info

  


  SO : Arch Linux

  


  When pavucontrol isn't open, pacmd list-source-outputs returns : 0 source output(s) available., but when pavucontrol is open :

  


  pacmd list-source-outputs | grep source

2 source output(s) available.
        source: 0 
                module-stream-restore.id = "source-output-by-application-id:org.PulseAudio.pavucontrol"
        source: 1 
                module-stream-restore.id = "source-output-by-application-id:org.PulseAudio.pavucontrol"


  


  What am I missing ? Why the ffmpeg works fine when pavucontrol is open ?

  


• Merge video and audio with ffmpeg. Loop the video while audio is not over

  9 septembre 2021, par fstephany

  I'm trying to merge an audio file with a video file.

  


  I have two options :

  


  


  • Have a very small video file (e.g., 10 seconds) that loop while the audio file is not over.

    


  


  • Have a very long video file (longer than any of my audio file) on which I can attach the audio file. I would like to cut the video when the audio is finished.

    


  


  


  I'm using the latter with the -t <duration in="in" second="second"></duration> option of ffmpeg. It means I have to get the duration of the audio file to feed it into ffmpeg. Is it possible to avoid this step ?

  


  Any pointer for the first solution ?