[Ffmpeg-devel] AAC decoder

Rich Felker dalias
Tue Mar 21 22:51:17 CET 2006


On Tue, Mar 21, 2006 at 10:05:44PM +0000, Benjamin Larsson wrote:
> Mike Melanson wrote:
> 
> > Mike Melanson wrote:
> >
> >>     One question: Is it really necessary to include tables for sine
> >> and KBD values? I know the sine table can easily be generated at
> >> runtime. The same probably applies for the KBD values.
> >
> >
> >     I decided to put my code where my mouth is. What follows is a
> > program to generate the sine tables, and also validates them against
> > the tables in your aac.h file. This will eliminate the hard-coding of
> > sine_long_1024[] and sine_short_128[]. I will see if I can figure out
> > an algorithm for the KBD stuff as well.
> >
> One algo is in liba52. It's an iterative bessel thingy :)

Have you RTFM'd libm? IIRC it includes functions to compute this for
you.. :)

Rich





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