Re: QDM* IMDCT

> On Fri, 19 Dec 2003, Sascha Sommer wrote:
>
> > You probably already compared this with dct36.c in mp3lib but are the
> > constants cosinus values?
>
> Actually, no, I didn't know exactly which DCT to compare it to.
> And I don't know what the constants are (will have to use some other tools
> to get those as they do not show up in my static disassembly).
>

Ah no I meant dct64.c there is lot of code which looks like this

 b1[0x00] = samples[0x00] + samples[0x1F];
 b1[0x1F] = (samples[0x00] - samples[0x1F]) * costab[0x0];

  b1[0x01] = samples[0x01] + samples[0x1E];
  b1[0x1E] = (samples[0x01] - samples[0x1E]) * costab[0x1];

  b1[0x02] = samples[0x02] + samples[0x1D];
  b1[0x1D] = (samples[0x02] - samples[0x1D]) * costab[0x2];

  b1[0x03] = samples[0x03] + samples[0x1C];
  b1[0x1C] = (samples[0x03] - samples[0x1C]) * costab[0x3];

  b1[0x04] = samples[0x04] + samples[0x1B];
  b1[0x1B] = (samples[0x04] - samples[0x1B]) * costab[0x4];

  b1[0x05] = samples[0x05] + samples[0x1A];
  b1[0x1A] = (samples[0x05] - samples[0x1A]) * costab[0x5];

Sascha






-------------------------------------------------------
This SF.net email is sponsored by: IBM Linux Tutorials.
Become an expert in LINUX or just sharpen your skills.  Sign up for IBM's
Free Linux Tutorials.  Learn everything from the bash shell to sys admin.
Click now! http://ads.osdn.com/?ad_id=1278&alloc_id=3371&op=click