[MPlayer-dev-eng] [PATCH] audio filter volnorm2 - two-pass audio normalizer

[Rich Felker]

On Sat, Jul 30, 2005 at 06:19:23PM +0200, Attila Kinali wrote:
> On Sat, 30 Jul 2005 09:58:38 -0400
> Rich Felker <dalias at aerifal.cx> wrote:
> 
> > I'm against this if it's left as a peak normalizer. Peak normalization
> > is always incorrect and morons keep asking for it, so they'll do it
> > more if a filter is available and ruin the sound. Instead it should be
> > RMS normalization.
> 
> Just out of curiosity, what's bad about Peak normalization and

It just has nothing to do with (perceived or energy-wise) loudness.

> how does it ruin the sound ?

It doesn't alone, but encoding a signal that attains the peak possible
sample value (or near it) often with a frequency-domain transforming
codec will distort the audio. Due to quantization, noise shaping,
etc., some extra headroom space below the peak is needed. The
distortions are usually audible, even to someone with bad ears like
me, and certainly visible with PSNR comparison.

Rich