[linux-audio-dev] Paper on dynamic range compression

John Rigg ladev at sound-man.co.uk
Wed Oct 18 08:44:57 UTC 2006


On Wed, Oct 18, 2006 at 07:23:12AM +0200, Jens M Andreasen wrote:
> A sine wave transient too fast for the compressor to handle immediately
> would then start out as a square with gentle rounded corners instead of
> a square with a flat-roof haircut. The distribution of the added
> frequencies is thus moved to lower octaves where the distortion is less
> dangerous/disturbing.

Soft clipping always sounds better than hard clipping, and there are
analog compressors that behave like this. Unfortunately even a soft
clipper generates significant harmonic distortion, largely 3rd and 5th.
The 3rd harmonic alone potentially increases the signal bandwidth by
three times, and aliasing will occur if the sample frequency isn't
high enough to accommodate all harmonics that have an amplitude greater
than the noise floor (below that it doesn't matter).

John



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