[MEncoder-users] Adjust Audio Volumes of Videos

[Joe Emenaker]

Malte Schünemann wrote:
> So this means I use e.g. volnorm=2:0.5 for the video with low setting 
> and volnorm=2:0.2 for that with high volume for encoding - correct ?
I don't think so. I've always just used "-af volnorm" without any "=" or 
anything following it, and I've obtained fairly good results.

I think you might not understand that this isn't a fixed volume 
adjustment regardless of what you're encoding. You don't need to listen 
to the video beforehand to find out how much you need to boost or cut 
it. Instead, volume normalization aims to do this automatically by 
analyzing the material at the time of playing/encoding. In other words, 
if you encode a variety of things (loud, soft, and medium) with 
"mencoder -af volnorm ....", you should end up with video files with a 
much more consistent volume than the originals.

Now, looking at the optional "method" parameter, it appears that you can 
change the overall volume that mencoder is trying to achieve. For 
example, using "-af volnorm=2:1.0" should cause mencoder to try to 
adjust the volume on *all* files you encode to 100% of the loudest 
possible sound allowable by the sound format you're encoding to. If you 
used, instead, "-af volnorm=2:0.4", then mencoder would try to adjust 
the volumes on all files you encode to about 40% of the loudest sound 
supported by the sound format.

So, the number you feed to the volnorm command does *not* seem to be 
based upon the loudness of the *source*. It seems to be the loudness you 
want all of the *destination* files to be.

- Joe