[XviD-devel] Request for ideas/comments about 2pass

[Edouard Gomez]

Hello,

I've been  digging deep into the current  2pass code and had  run lot of
tests now.

On the one hand, i can say  that the file size control works. It is very
accurate ... I had never undersize/oversize surprises. 

On the other hand, the current implementation is far too aggressive with
bframes. I remember we talked a lot about the fact that a linear formula
to compute a bframe quant from a  pframe quant was not a good idea. That
was at that time that we decided to introduce the offset/ratio parameter
couple.

But this file (http://ed.gomez.free.fr/vrac/pass2.txt) shows clearly the
current 2pass code is acting exactly like we wanted not. It uses far too
high quants for bframes compared to their reference frames.

I did  not locate the  exact code that  is responsible for such  an high
difference. So i call for some ideas on how to avoid that. 

Btw,  i have  also another  question.  Current  plugin includes  2 algos
(altCC and linear scaling) that share most of the code, but it is really
hard to read the code because of the too many if/else paths due to their
mix in the source. What about splitting  the plugin into 2 files ? Or we
could  separate them at  the xvid_plugin_2pass2  level checking  for the
altcc field in the rc structure... it would be much more clean.

-- 
Edouard Gomez-------------- next part --------------
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