Re: normalize-audio and video files

[Nicolas George <george@nsup.org>]

L'octidi 28 messidor, an CCXXIII, Darac Marjal a écrit :
> You could try stripping the audio from the MPEG file, normalising it and
> then recombining it.
> 
> So, to extract the audio from the video, try something like:
> 
>  avconv -i video.mp4 -vn -acodec 'copy' audio.out
> 
> (check "avconv -i video.mp4" to see what format the audio will be)
> 
> And to recombine the audio, use something like:
> 
>  avconv -i video.mp4 -i audio.out -map 0:0 -map 1 \
>   -vcodec copy -acodec copy new_video.mp4
> 
> That will combine stream 0 from the first file (which will PROBABLY be
> the video, but check with "avconv -i video.mp4" again) with all of the
> second file (the audio).

If using that kind tool, then better use a real recent FFmpeg (either using
the one from Sid or building from source), because it has the following
filters that allow to do more work directly:

https://ffmpeg.org/ffmpeg-filters.html#volume
(also present in avconv) -> to change the volume of the audio by a fixed
factor

https://ffmpeg.org/ffmpeg-filters.html#compand
(also present in avconv) -> "compress or expand the audio's dynamic range"

https://ffmpeg.org/ffmpeg-filters.html#ebur128
(NOT present in avconv) -> measure the volume

https://ffmpeg.org/ffmpeg-filters.html#volumedetect
(NOT present in avconv) -> same as previous, but less accurate and much
faster

Regards,

-- 
  Nicolas George