[XviD-devel] Question about bvop decoding

[Michael Militzer]

Hi,

only 3% of total blocks are interpolated?? You mean 3% of the total blocks 
in a sequence or 3% of all B_VOP blocks? In any case, I think the function
decoder_bf_interpolate_mbinter should be called more often because it is
used for mode DIRECT and mode INTERPOLATE MBs (iirc). And direct coded MBs
should be dominating (probably around 70% or more of the total B_VOP MBs).

Michael


Quoting Edouard Gomez <ed.gomez at free.fr>:

> Edouard Gomez (ed.gomez at free.fr) wrote:
> > we do spend an
> > incredible amount of time in decoder_bf_interpolate_mbinter
> > (something like 14% of cpu time) though it's just a function
> > that calls more CPU intensive functions like qpel/halfpel
> > interpolation functions and so on.
> 
> I added some debug code in decoder, and i got this:
> xvid: interpolated 19507156 blocks out of 637555200 total blocks.
> 
> so interpolated blocks represent 3.05% of total blocks. If I assume
> these blocks require something like 1 or 2 times more cpu cyles than
> usual forward/backward blocks (they require the interpolation of
> both backward and forward refs, and then call the usual inter
> decoding function). This should max at 9% total CPU time, including
> all interpolation, compensation code. But as i said,
> decoder_bf_interpolate_mbinter represents 14% of total CPU
> cycles + all calls to sub functions (hard to tell how much, as
> these functions are also called by other inter block decoding
> functions, and oprofile lacks call graph output)
> 
> I'd like to be completly wrong... buit who's going to tell me
> where ?
> 
> -- 
> Edouard Gomez
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