[LAU] Gain and clipping wav -> lame

[Will Godfrey]

On Thu, 25 Jul 2013 16:14:20 -0400
Martin Cracauer <cracauer at cons.org> wrote:

> Fons Adriaensen wrote on Thu, Jul 25, 2013 at 07:40:53PM +0000: 
> > On Thu, Jul 25, 2013 at 02:21:50PM -0400, Martin Cracauer wrote:
> > 
> > > Does anybody know why wav files that do not have clipping would clip
> > > when encoding them with lame?
> > 
> > Because the peak sample value says nothing about the real 
> > level. Take a square wave with peak values +/-1. It is the
> > sum of a number of sine waves, with frequencies  1,3,5,7,...
> > times the frequency of the square wave. The first one has
> > a peak value of about +/-1.27, that is +2 dB. So any encoding
> > that looks at the spectrum (and mp3 does) will see a level
> > that is +2 dB.
> 
> Ah.  Makes sense.  Thanks so much!
> 
> Is there a rule of thumb how many db less I should give music to avoid
> this? What would be the value for pink noise starting at 40 Hz?

I always finalise a wav file in Audacity with the peak level at -1dB. Seems to
work for me :)

-- 
Will J Godfrey
http://www.musically.me.uk
Say you have a poem and I have a tune.
Exchange them and we can both have a poem, a tune, and a song.