[Flac] FLAC: track and album gain?

Ivo Emanuel Gonçalves justivo at gmail.com
Mon Apr 2 06:03:54 PDT 2007


On 4/2/07, Harry Sack <tranzedude at gmail.com> wrote:
>  But how can this be possibly lossless? You change the volume of the audio
> tracks, so isn't this lossy or does the actual volume of a track isn't
> considered as "audio quality"?

Replay Gain is an audiophiles thing.  Personally, I love it.  And I'd
also love if you had follow my suggestion and look into Wikipedia.
Instead, I'll just copy/paste the relevant bits that you want to know.

"Replay Gain is a proposed standard published in 2001 to normalize the
perceived loudness of computer audio formats such as FLAC and Vorbis.
It works on a track/album basis, and is now supported in a growing
number of players.

Replay Gain works by first performing a psychoacoustic analysis scan
of the entire audio file to measure the perceived loudness and peak
levels. The difference between the loudness and the target loudness
(usually 89 dB SPL[1]) is calculated; this is the gain value.
Typically, the gain value and the peak value are then stored in the
audio file as metadata, allowing Replay Gain–compliant audio players
to automatically attenuate (or in some cases amplify) the output so
that such files will play back at similar loudness to one another.
This avoids the common problem of having to manually adjust volume
levels when playing audio files from different albums that have been
mastered at different levels. Another benefit of Replay Gain scanning
is that the peak information can also be used to prevent loud songs
from clipping. Finally, should the audio at its original levels be
desired (i.e. for burning back to hard copy), the metadata can simply
be ignored."

-Ivo


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