[FFmpeg-devel] pre discussion around Blackfin dct_quantize_bfin routine

Michael Niedermayer michaelni
Tue Jun 12 09:50:13 CEST 2007


On Mon, Jun 11, 2007 at 10:58:00PM -0400, Marc Hoffman wrote:
> Hi,
> This is my rough draft it works well with the small precision errors  
> due to 16bit arithmetic, actually its the same (as far as I can tell)  
> as the MMX quantizer. I ran my reference fixpoint against the mmx and  
> it seems to work on the cases I tried, its 1 bit off which seems  
> about right considering the truncation of the coeffs from 22 to  
> 16bits.  Can someone look over my shoulder and give a peak. I know I  
> have to clean up the codes a bit but I wanted to get someone else to  
> review my work up until now.  I have used inline asm, Michael this  
> should be pretty straight forward for you to get your head around.   
> This doubles the performance roughly.

your code seems to ignore the idct permutation
try to set FF_IDCT_INT

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Concerning the gods, I have no means of knowing whether they exist or not
or of what sort they may be, because of the obscurity of the subject, and
the brevity of human life -- Protagoras
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