[FFmpeg-user] Preserving perceived loudness when downmixing audio from 5.1 AC3 to stereo AAC

[Nicolas George]

Le septidi 27 thermidor, an CCXXI, Francois Visagie a écrit :
> Is it possible to normalise audio levels using ffmpeg? The 'pan' filter
> documentation mentions:

Define "normalize".

> "If the ‘=’ in a channel specification is replaced by ‘<’, then the gains
> for that specification will be renormalized so that the total is 1, thus
> avoiding clipping noise."

Read carefully: "so that the total is 1", "avoiding clipping". That is
exactly what was discussed in this thread.

> I.e., having downmixed to stereo, can one expect correct normalisation
> from '-filter:a pan=stereo:c0<c0:c1<c1'?

This filter does nothing, obviously.

> If not, does ffmpeg provide a better mechanism, or is something like that
> in planning?

There are mechanism, they are mostly good, but you are not specific enough.

Regards,

-- 
  Nicolas George
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 198 bytes
Desc: Digital signature
URL: <http://ffmpeg.org/pipermail/ffmpeg-user/attachments/20130814/d03cbef6/attachment.asc>