HI,
Is there any limitation to the value 'big_values'. in ISO 11172 layer-3?
From the specs I gather, there are 21 scale factor bands(for long blocks). So the last index value of the last scale factor band, should limit the number of 'big_values'. For example at 44.1Khz, the 'index of end' for the last scale factor band(on page 63 of the iso 11172 spec) is 417, which means that at most there can be 418 coded frequency lines in the granule, which to means that 'big_values' cannot be grater than 209(418/2).
So I infer that, there is IN FACT a limitation to the 'big_values'. Is what i infer correct? Can any body let me know?
Kr,
Aviral Mittal

I always thought that the bit reservoir and the big values can have a maximum of 512.

There are 22 sfb, not 21. However, the last one doesn't have any scalefactor.

Regarding the big_value question, I think that it can cover the whole 576 values. It is stored on 9 bits per channel, so it is able to handle the whole range.

Thanks Gabriel,
I know that its a 9 bit field.
I just had a doubt that if 'big_values' is indeed limited to as I thought, then how come in some of the .mp3 files 'big_values' = 288. But since you said there are 22 sfb and not 21, so I guess, its ok now.
Kind regards,
Aviral Mittal.

It is probably because of a lowpass.
You can try the following:

Lame -b 128 --lowpass 12 input.wav output.mp3
with a 44.1kHz file. You will then see that the max big_values of this file is quite low.