[vorbis] Beta4 artifact/bug in the bass area

[Segher Boessenkool]

"Rajko.Jersic" wrote:
> 
> Hi!
> 
> Exactly!
> 
> I belive, that solving this low frequency artifact, will also help reducing
> the clipping in low bitrate modes.
> The lower bitrate you use, the more clipping ocures, maybe some frequencies
> are amplified to much somehow.

Clipping is mostly caused by problems in the representation of
lower frequencies. Low frequencies have a much bigger amplitude
(Amp ~~ freq^(-1/2)) for the same energy). If "low" bitrates (I
assume you mean 20..40 kbps/channel) causes much more clipping than
"higher" (40..80 kbps/channel) encodings, this would point to a bug
in the encoder. Or (in this case much more likely), the encoder simply
isn't tuned for these low bitrates (yet).

On the bright side, my evil 754-by-integer lsp code as a side effect
dimishes the amount of clipping. And Monty seems to like this code.
So we all can go to bed and sleep well :-)

Dagdag,

Segher

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