> From: Takehiro Tominaga <[EMAIL PROTECTED]>
> Date: Sun, 26 Dec 1999 18:55:41 +0900
>
> I implemented "--noath" option for CVS.
> As you imagine, it disable the ATH masking effect.
>
> This could be some ATH matter problem's work arround, like gspi35_1.wav
> ---
> Takehiro TOMINAGA // may the source be with you!
> --
How about a --athlevel instead or in addition? It could specify the
normalization used on line 229 of quantize.c. The value used now is
114, and setting it to something much larger (like 200) effectively
disables the ATH.
I'm still not sure the gspi35_1.wav problem is caused by the ATH.
I think it is actually caused by other flaws in the psy model.
My reasons are:
1. using --athonly -V5 doesn't have the problem (in this case lame is
choosing the bitrate so there is no audible distortion based only on the ATH)
2. any change which reduces the masking, such as using MAXNOISE
for the noise calculations, or replacing the spreading function
with something more reasonable, will also fix the problem.
Speaking of masking functions, I coded up the AAC recommended masking
function. (not yet the default) It is very similar to the MPEG1
spreading function, with some slight changes to the formulas which
seem to fix all the bugs in the MPEG1 ISO documentation description
and dist10 implementation.
Mark
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