[FFmpeg-user] Increasing audio

[Moritz Barsnick]

On Sat, Apr 01, 2017 at 23:41:21 +0200, Cecil Westerhof wrote:
> > You can use then use that value for the volume filter - note the
> > "dB" syntax:
> >
> > $ ffmpeg -y -i speaker.MP4 -vcodec copy -af volume="7.7 dB"
> > speakerAudioInc.MP4
> 
> Almost all give 0.0 dB (12), or -0.0 dB (4). When using that there
> will change nothing. Or am I overlooking something?
> There is also a -0.4 dB and a -0.2 dB.

0 dB change indeed means no change (it's a logarithmic scale - sorry if
that's too mathematical for you). In other words, the loudest parts of
the file are already at maximum, and raising their volume will
introduce clipping, what could be perceived as distortion. Apparently,
even at "volume=3", it's not noticable to you yet, at "volume=4" it is.

Did you try dynaudnorm? If "volume=3" isn't good enough for you, it
could be a better solution.
https://ffmpeg.org/ffmpeg-filters.html#dynaudnorm

Moritz