VideoHelp Forum

Our website is made possible by displaying online advertisements to our visitors. Consider supporting us by disable your adblocker or buy Replay Video Capture or PlayON and record Netflix, HBO, etc! :)
+ Reply to Thread
Results 1 to 3 of 3
Thread
  1. Hello - I know questions like these are asked a lot, but I have a slightly tricky issue.
    I have about 30 video+audio files that have been captured incorrectly. They are mp4 H.264 with stereo AAC audio.
    The video is fine and I don't want to re-encode that. The stereo audio is about -20db on the right leg.

    What would be syntax of a windows FFmpeg command be to copy the video and left stereo audio leg and add 20db gain to the right leg only to a new file?

    Any guidance much appreciated.

    Thanks all - Duncan.
    Quote Quote  
  2. Try:
    for %%a in (*.mp4) do ffmpeg -i %%a -c:v copy -af dynaudnorm=n=0 "output\%%~na.mp4"

    That should normalize the channels independently (to same level). If you want to do a "stupid" gain you probably have to split the channels and then do the "normal" gain or normalization filter.

    Are they "real" stereo files? If they are not I would just convert to mono, or stereo but just by duplicating the left channel.

    https://superuser.com/questions/323119/how-can-i-normalize-audio-using-ffmpeg
    https://trac.ffmpeg.org/wiki/AudioVolume
    https://trac.ffmpeg.org/wiki/AudioChannelManipulation
    https://ffmpeg.org/ffmpeg-filters.html#dynaudnorm
    Quote Quote  
  3. **really helpful** thanks you. For my purposes this approach worked just great.
    For anyone in a similar situation, I had to make one tiny adjustment to increase the gain range to 20db

    ffmpeg -i %%a -c:v copy -af dynaudnorm=n=0:m=20.0 "output\%%~na.mp4"

    Your expertise is much appreciated.
    Quote Quote  



Similar Threads