[vorbis] (Un)Usefulness of Vorbisgain?

[Moritz Grimm]

Luke Usherwood wrote:
(like OGG).  In the musical world, compression is "adjusting (reducing)
the dynamic range of the sound, usually by making softer bits of the
music louder".  For example a compressor is commonly used on an electric
guitar to even-out the volume of the notes being played.

Not entirely true ... a compressor is like an audio engineer pulling
down a fader every time the volume exceeds a certain treshold, who has a
certain reaction time (attack) and waits a while until he pushes the
fader back up (release). It only removes the peaks. You can then raise
the volume of the flattened waveform, but that's not what a compressor
usually does. Those are called "loudness maximizers" then and are
usually among the last steps in mastering to make better use of the
dynamic range of the target medium, hopefully in a decent way.

Compression alone is used mostly on single instruments, e.g. on vocals
where pops and sharp 'sss' sounds can create ugly peaks that should be
removed. So, a compressor removes the peaks, and a maximizer is a
compressor/limiter (limiters are compressors with a very high
compression ratio, i.e. no peaks can really get over the treshold) with
some gain applied. To make the whole off-topic thingy complete, there
are also expanders that work like compressors, just the other way round
(they keep a minimal volume).

My opinion/hint is to avoid all these tools when playing back music.
They do more bad than good when applied cluelessly, and the clue is
usually with the audio engineers who already applied them during the
mixing and mastering stage.

Replaygain doesn't apply any compression, it just raises or lowers the
volume. As you can see in
http://privatewww.essex.ac.uk/~djmrob/replaygain/player.html ,
compatible players have a hard limiter to prevent digital clipping. This
hard limiting won't help much if your pre-amp is cranked up too high (it
will create distortion nonetheless and propably sound like analogue
clipping eventually).

<p>Moritz

<p>P.S.: There's an all-in-one DirectX plugin out there by iZotope called
"Ozone". It also comes as a Winamp plugin (*brrrrr*). Anyways, the DX
version is great, and they've written a mastering guide for it. Even if
you're not into mastering, or Ozone, or whatever, it might give much
insight to the interested:
http://www.izotope.com/products/audio/ozone/ozoneguide.html

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