Dynamic range compression tool...

[Derek Broughton]

James Gray wrote:

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> Paulo Matafome Oleiro wrote:
>> Seg, 2006-07-24 às 18:19 +0200, Andrea Giuliano escreveu:
>>> mp3 audio file (or wav file, maybe) so that the difference in
>>> loudness between very loud passages and very low passages
>> Sincerely
>>
>> The only program that I know is MP3 ReplayGain (mp3gain) to get all
>> the track louder.
>> This should be available at the repositoires
> 
> The only thing this program does is read the entire MP3, find the peak
> value, and bumps the total gain up or down so the peak matches whatever
> you want it to be.  

Not according to the designer:
"Replaygain is different from normalization. In normalization, you merely
ensure that the peak amplitude reaches a certain level. However, songs
with 'spiky' waveforms might not be amplified enough. The replaygain
technique measures the effective power (i.e. RMS after an Equal Loudness
Filter) of the waveform, and amplifies the waveform accordingly. The result
is that replaygained waveforms are usually more uniformly amplified that
normalized waveforms."
http://wiki.hydrogenaudio.org/index.php?title=Replaygain

> I usually encode my MP3 from the CD's and "normalise" them at the same
> time.  

"normalise" aiui, actually _does_ recode the mp3 - better if you have an mp3
player that doesn't actually understand the gain tag in the MP3, but
introducing yet another chance for loss from the original.

> Imagine the difference between the perceived 
> sound of a mellow classical piece with a big crescendo finale being
> "peak analysed" as opposed to averaged - the bulk of it would be
> quiet-as-a-mouse, whereas the averaging method will lift the bulk while
> letting the big finale blow your eardrums :P  Just what the composer
> wanted!

Yeah, but the composer didn't want you to listen to it in a car either :-) 
Compressed dynamics are really helpful for that.
-- 
derek