Audio rescaling vs. normalization

[Ranguvar]

What's the difference, please?

http://www.exit1.org/dvdrip/doc/index.cipp (Sections 2.8.3.7, 2.3.7.9, and 5.9)

[tebasuna51]

Normalize, Maximize, Audio rescaling, ...
Is apply a fixed amplification value to all the audio. The amount of amplification is calculated in a first scan to guarantee the max peak is not clipped. The audio is only amplified.

Dynamic Range Compression, Boost, ..
Is apply different amplification (or atenuation) to low or high volume values. These procedures are only recommended at play time (neighbours, noisy room, ...) and never in transcoding operations because the original quality is lost.

[Ranguvar]

Then why do they have both normalization and audio rescaling as separate options?

[Slogra]

Most people think that CD audio is the standard for volume, while most CDs are actually way too loud (no dynamics and clipping all over the place).
So they also want DVD sound at that same volume. Only way to do that is to remove all dynamics (dynamic range compression or the other "tools" mentioned above). If you go too loud you'll get clipping as well, but that seems to be the standard nowadays. :sly:

Like tebasuna51 said, it's much better to apply dynamic range compression at play time when you actually need it. Like in a car with lots of background noise or when you don't want to wake your neighbours with loud explosions in a movie etc.

Car stereos have a loudness button and receivers have a dynamic range compression option for that.

[tebasuna51]

Then why do they have both normalization and audio rescaling as separate options?

Seems two methods to obtain the same thing with different soft (mplayer), but I don't know this package.

Often the word Normalize is used to equate the volume (rms) of more than one source.

[Ranguvar]

Alright, thanks for your help :)