extreme grey blocks

[tenebrenz]

I seem to have stubmled across something which causes XviD great difficulty. The opening credits to the movie (Suspiria) are static white text on a black background and becomes full of grey blocks no matter what res or bitrate I use. I have attached an image showing the problem, though it'll probably have to be authorised.

I have tried lots of different settings in XviD-17042002-1(koepi) and switching mmx on / off, etc but they won't go away. I have tried changing fourcc to DivX but the problem still remains so it doesn't seem to be a playback issue. I have also encoded the same scene with DivX 3.11, similar problem in few frames & DivX 4.12 with no problem.

[-h]

Totally cool. Could you try the latest CVS build (some stuff has changed lately), and see if it still occurs?

If it does, could you try to create a very short clip of the source (with huffyuv would be good), and make sure it exhibits the artifacts when you encode it? If we could get our hands on that short clip, it would make tracking down this bug much easier.

-h

[tenebrenz]

Just tried to use uManiac's build XviD.Alpha.28.04.2002.0000 but it doesn't install properly and isn't an available codec but I also tried an earlier XviD build from the beggining of the month and it appears there also. I have attached a 6 frame avi compressed with huffy which exhibits the problem if re-encoded.

[-h]

Thanks a heap.

As always, could people please only download the clip if they have a legitimate need for it.

-h

[-h]

I just tried it with an almost-CVS-but-not build, and the artifacts still appear to be present (albeit in a diminished way).

With quant=2 they're extremely apparent, just as in your screenshot. At quant=3 they are present, but quite faint. At quant>=4 they don't appear to be present at all.

Very interesting. Seems to be an quantization overflow issue, but that really shouldn't be happening..

-h

[Psyche]

If you want to see something funny, encode the clip with DivX 3.11... Youl see exactly the same artifacts, only a little worse, but then they start to disappear during the subsequent frames.
DivX 4.12 doesn't show this behaviour.
Aaaaaanddddd!!!!!!!! The most important! I tried with a pre 2.0 core (avih's page, dated March 02, 2002, you foreigners have a strange taste for dates format :p ) and the blocks don't appear. Tada!

EDIT: ffmpeg doesn't show any problems.