[XviD-devel] About xvid source assembly language optimize(why it does not work?)

李冰 bing.li at autosoft.com.cn
Tue Nov 18 07:01:51 CET 2008

Dear  Everybody:

   I download the  xvid 1.1.3 source code , and i compiled the source  under Fedora Core 8. 
  Then I compile xvid_decraw.c.
  And I run with the command: 

  ./xvid_decraw   -i input.m4v   -m 
  then it work well, and output the bitmap file. but it is rather slow.
  Then I use the command below:
  ./xvid_decraw   -i input.m4v   -asm -m 
  Hence I think i used  -asm option ,  the decoding speed should be  accelerated.

  But .... I find that the result is unchanged with the  non-asm execution result .

  input.m4v is a raw 720x568 mpeg4 video sequence, .

  I wonder whether the -asm  option worked!
  So i test  the fdct and idct, they have been assigned to  fdct_mmx_skal and idct_mmx respectly.

  But why it does not accelerate?

  So i use a small script to test the  fdct_c and  fdct_mmx_skal.  To run 1000000 times ,
  the fdct_c consume 2.7 seconds  and fdct_mmx_skal need 0.8 second on my computer. 
  It seems that asm code should be much faster.  But why xvid decoding can not be speeded up?

  Thanks very much !


Ice Lee

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