[XviD-devel] zero-biased dequant/idct
daniel smith
xvid-devel@xvid.org
Mon, 29 Jul 2002 01:31:15 +0800
i just remembered a paper i skimmed over that i
wanted to try out to speed decoding (i will
benchmark this afternoon unless someone's
already tried it):
- trap the number of bits required to store coeffs
during mb decoding
- if coeff bitcount for block is below a threshold,
call versions of dequant_inter / idct which include
a zero-byte skip check for every 8 bytes of
block[64]
yes we lose time with branch mispredictions, but
is the zeroed content of inter blocks high enough
to justify? has anyone already tried this out with
our mmx code?
this could perhaps aid encoding speed as well,
using the sum of quantized coeffs as a trigger
during dequant/idct stage.
dan
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