Hi Naoki!
> I think it is certain that this problem is caused by noises
> concentrated on pure tones.
> A noise on a single MDCT coefficient increases as it's
> amplitude increases. This is because quantized values are
> actually values powered by 3/4.
>
> According to the theory of psychoacoustic, it is a wonder
> why using average noise rather than MAXNOISE succeeds.
Maybe because the quantization noise is considered to be
band pass white noise in that band?
> Perhaps this is the answer of this question:
> The reason why vbrtest problem is not apparent in most cases
> is that if a calculated noise of an MDCT coefficient exceeds
> the masking threshold of it's SFB, this means that amplitude
> of that coefficient is large and thus it makes larger masking
> itself. So, real masking of it's frequency is larger than
> calculated masking of it's SFB.
>
> Perhaps the most clear solution is to calculate masking of
> all MDCT coefficients, and use MAXNOISE. But this is too
> expensive. Perhaps a reasonable solution is detecting peaks
> and calculating these maskings separately.
Another solution is a more sophisticated spreading function
taking into account the tonality and loudness of the signals
being spreaded.
> --
> Naoki Shibata e-mail: [EMAIL PROTECTED]
By the way: have you tried --noath ?
Robert
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