Warped background textures with XviD

[Cyberia]

I am noticing some strange 'warping' effects occurring on background textures during playback. It is reminescient of the blocking problems Div3 would have in the same situation, but it's different. The background seems to warp and swim around while the foreground characters are well defined and clear.

I'm sorry I can't describe it better. But it happens worst when the camera is NOT moving. Panning actually alleviates it somewhat. (as opposed to the Div3 problem where it got worse)

The warping is NOT present in source (opened through AviSynth)

I am new at XviD, but have read the guides and I am using the setting verbatim from the guide. (MPEG-4_XviD_Koepi_24062003-1_Encoder_Guide_ver20030701.pdf)

The final file is 2h6m long with 1.2GB filesize. Bitrate does not seem to be the issue.

Is there something I can do to help this?

[greycortex]

It looks like there's some noise causing those background blocks to move. Are you enabling chroma motion, for instance? Try disabling it if this is the case. If you want to enable this, try reducing noise in your source with Convolution3d or some other temporal filter. If I'm wrong in this, someone correct me please, as this is what I do to avoid this particular problem.

[Selur]

Yuo, could be a problem with qpel and a noisy source

Cu Selur

[sysKin]

Nono guys :)
It's idct problem :/

Cyberia: Go to ffdshow options (I'm assuming you are using ffdshow - if not, you should start;) ), and in 'miscellaneous' tab change idct to 'xvid' (or if it's xvid, change it to 'simple'). Should help.

Radek

[Cyberia]

Well, idct is set to like you asked already, but

The background is noisy (very) but it is supposed to be. It is occuring on close shots of the actors, and the background is necessarily out of focus and grainy. However, it is not a moving background (cars, trees...) It is the side of a building, with nothing moving.

qpel & chroma motion are on and set like the guide.

Ill try again tonight without CM.

[Cyberia]

Well, idct is set to Simple16383 already, but the source is a PAL SVCD so, I am opening it through MPEG2DEC3 and using it's 64-bit FP idct. So I don't think ffdshow is coming into play at all.

The background is noisy (very) but it is supposed to be. It is occuring on close shots of the actors, and the background is necessarily out of focus and grainy. However, it is not a moving background (cars, trees...) It is the side of a building, with nothing moving. Once you notice it, the effect is quite distracting because it looks like the side wall of the nearest building is warping and distorting.

qpel & chroma motion are on and set like the guide.

Ill try again tonight without CM.

EDIT: Sorry for the 'double' post, my browser freaked out. I was lucky not to lose the whole thing. I didn't realize it had also actually posted the partial post when it freaked. You can delete it.

[Koepi]

The noise (grain) is what is causing your troubles.

Koepi

[olorin]

Originally posted by Cyberia
necessarily out of focus and grainy. However, it is not a moving background (cars, trees...) It is the side of a building, with nothing moving. Once you notice it, the effect is quite distracting because it looks like the side wall of the nearest building is warping and distorting.



I have had exactly the same problem, so you could try what works for me which is: use custom matrix hvs-better. At least in my tests there is a big difference between this one and for ex mpeg matrix when it comes to these warping backgrounds.