[Ffmpeg-devel] AAC decoder
Mike Melanson
mike
Tue Mar 21 22:13:28 CET 2006
Benjamin Larsson wrote:
> And the sine_short table should be a subset of sine_long.
That seems intuitive, but I don't think it's true in this case. The
short values are derived as:
for odd values i in 1..127
sine_value = sin(i * PI / 512)
For long values:
for odd values in 1..1023
sine_value = sin(i * PI / 4096)
In the short formula, you could multiply (i * PI / 512) by (8/8) to get
the same denominator as in the long formula. But multiplying by 8 would
make the numerator even and thus the sine value would not occur in the
long table.
(I think.)
--
-Mike Melanson
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