[FFmpeg-devel] [PATCH 2/2] lavfi/volume: support volume normalization through metadata.

[Nicolas George]

Le nonidi 9 ventôse, an CCXXI, Clement Boesch a écrit :
> I'm not sure how the expression eval would really help, but I could make
> ebur128 inject the volume adjustment instead of making af volume compute
> it.

We already have expression eval, that is not the issue. The issue is that
Stefano proposed a patch to re-evaluate the expression for each frame. With
this patch, volume normalization becomes almost trivial, it is just a matter
of using the correct expression.

> Basically you have:
>     M: analysis of the last 400ms
>     S: analysis of the last 3s
>     I: overall
> 
> I and S are fairly decent for "real-time" normalization.

Even 3 seconds is rather too short for volume normalization. Furthermore, if
I understand you correctly, S(t) is the loudness for the ] t-3s; t ]
interval. IMHO, volume normalization would require some lookahead too,
probably with a symmetrical interval.

Regards,

-- 
  Nicolas George
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