[FFmpeg-devel] pre discussion around Blackfin dct_quantize_bfin routine

Marc Hoffman mmh
Tue Jun 12 11:49:19 CEST 2007

Does these allow me to ignore the DCT permutation?

yoda:~/ffmpeg-svn/libavcodec/bfin mmh$ svn diff dsputil_bfin.c
Index: dsputil_bfin.c
--- dsputil_bfin.c      (revision 9231)
+++ dsputil_bfin.c      (working copy)
@@ -285,6 +285,7 @@
      c->put_no_rnd_pixels_tab[0][2] = bfin_put_pixels16_y2_nornd;
      c->put_no_rnd_pixels_tab[0][3] = ff_bfin_put_pixels16_xy2_nornd;
+    c->idct_permutation_type = FF_NO_IDCT_PERM;
      c->fdct               = ff_bfin_fdct;
      c->idct               = ff_bfin_idct;
      c->idct_add           = bfin_idct_add;
yoda:~/ffmpeg-svn/libavcodec/bfin mmh$


On Jun 12, 2007, at 3:50 AM, Michael Niedermayer wrote:

> Hi
> 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
> [...]
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