Re: Re[2]: [XviD-devel] motion compensation->inter4v->BFRAMES->chroma bug?

["Milos Spasovic" <mfluder@xxxxxxxxxxx>]

On Thu, 22 Aug 2002 14:03:09 +0200, "Marc FD" <marcfd@xxxxxxx> said:

> PS :does TOOSMALL_LIMIT = 3 gives impressive size improvements ??
>     because even with sp4, my build gives me a 21 Mb file at const
>     quant 2 vs 22,5 for koepi's. visally checked quality (no PSNR
>     test) and i couldn't tell any differences...

If you read through your mails you 'll see that this was already
discussed (last Sunday I think). It was me who pointed out that coeff
thresholding removes too much details which is of course true, hence
the big drop in filesize (by not coding some coeffs). If you are
encoding anime (which I presume you are by reading your posts on Doom9)
then you will not notice any difference because there are not so much
details in anime. But if you try some movies you will certainly notice.
The best description I can give is that the image with MPEG
quantization and coeff thresholding enabled looks like the image with
H.263 quantization without coeff thresholding.

And if I remember corectly there was already coeff thresholding in XviD
(in January I think) and then Isibaar disabled it because he said it
was not good for high quality encodings - He was right :-) Anyway,
gruel and Isibaar already found solution for this and will implement it
when new API 3.0 is introduced.

And don't get me wrong, I'm just doing my best that coeff thresholding
doesn't be enabled by default because I think it is a very very bad
thing if you want to have the best MPEG-4 codec. It would be best if
this could be user selectable but it would just do more harm than good
for regular users.

Best regards,
Milos
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