[XviD-devel] some bframes ideas

[Radek Czyz]

Hi,

I was thinking on how to make bframes better - in terms of quality,
decision, dark blocks etc. I performed a few tests, too.

My main idea is to decrease bframe's size in a different way than
increasing quantizer. I already tested coefficients thresholding, as
it used to be done in pframes. As you might remember, TOOSMALL_LIMIT
of 3 gave the best PSNR, but was blurry.
I tried it in bframes and it seems to give very good results - for
example, when bframes have the same quantizer as pframes, the filesize
is smaller (5 - 10%) while there is completely no visible artifacts.

A different idea - which I haven't tried yet - is to substract a
fraction of a quantization error form coefficients (up to half of
maximum error). @ MfA: thanks for this, sounds very reasonble.

A simple question is: do you know other, simple and fast ways to
decrease bits needed? Trellis quantization sounds great, but seems
slow... and I would prefer ways which could be integrated into BITS
stuff. There is no BITS for bframes but who knows, maybe there will be
:)

Ah and another question - would you like me to commit my newest code?
It includes a series of cleanups and doesn't produce dark blocks, but
is not tested too well (as opposed to current code, which is tested
and proven to be ugly...)

Regards,
Radek