Repeated Green Coloration in Movie

[elm]

Hello,

I've a problem with the encoding to xvid.
My encoded video first looks normal, then it slowly gets more and more green coloration (see second screenshot). After about 15 seconds it switches back to normal color (see first screenshot), stays there for about 10 seconds, then turns green again.

http://img218.imageshack.us/img218/1918/untitled2ui6.th.jpg (http://img218.imageshack.us/my.php?image=untitled2ui6.jpg)
Normal Color
http://img212.imageshack.us/img212/4140/untitled1bl2.th.jpg (http://img212.imageshack.us/my.php?image=untitled1bl2.jpg)
Green Colored

The problem persists over different encoding options. My default options are just the target size and vhq=4, but I also tried different combinations like vhq=4:chroma_me=1:chroma_opt=1:trellis:gmc:hq_ac, with no effect.

Im using the original xvid sources for gentoo, version 1.1.0-r1 with mencoder version 1.0_pre8-r1.
This seems to be a special problem with the source material / encoding options since the same combination encodes different vobs without problems.
The problem occurs with several dvds from the same tv series.

Here is the whole mencoder command line (second pass, first pass has the same options except it sais first pass):
#mencoder mar3-001.vob -ovc xvid -xvidencopts pass=2 \
-xvidencopts bitrate=-126000:vhq=4:chroma_me=1:chroma_opt=1:trellis:gmc:hq_ac \
-o tmp0.avi -vf lavcdeint,scale=640:480 -oac mp3lame -lameopts abr:br=192

Any ideas if this is a bug or how to eliminate this problem?

Thanks & bye,
elm

[skal]

Hi

it's most likely a *decoding* problem, known as 'idct drift'. What are you playing the file with? try another decoder if possible.

hope it helps,
Skal

[elm]

Hi,

thanks for your reply, especially the problem classification. I've tried to find other problems in regard to idct drift, but there is not much mentioning of it, mostly just in the sources or the developer mailing lists.



it's most likely a *decoding* problem, known as 'idct drift'. What are you playing the file with? try another decoder if possible.


I tried playing it with mplayer on Linux and Windows and Windows Media Player Classic on Windows. Linux used xvid 1.1.0-r1 as decoder, mplayer for Windows some older version (1.0.x) and the Media Player Classic with XviD-1.1.0-30122005 _Final Release_ (AFAIR the file is from doom9).

So its probably not dependent on a specific version of xvid (if its a decoder problem).

Any other suggestions?

bye & thanks,
elm

[skal]

Hi

the problem i was mentioning is also called 'idct mismatch'. There's more about that around...

now, it's strange all the decoders have the same problem playing back the file. Btw: did you have a look at the source? Maybe it's a problem with decoding the .vob...
If not, try removing some of mencoder's -xvidencopts, one by one, until the problem disappears (if it does). Could help identifying where it comes from, if it's in the encoder.

Skal

[elm]

Hi,


the problem i was mentioning is also called 'idct mismatch'. There's more about that around...


Thanks for the hint.


Btw: did you have a look at the source? Maybe it's a problem with decoding the .vob...


The source looks fine with the mentioned players (mplayer unix/win and Media Player Classic).


If not, try removing some of mencoder's -xvidencopts, one by one, until the problem disappears (if it does). Could help identifying where it comes from, if it's in the encoder.


I tried it already with everything except the vhq=4 and bitrate removed. I'm running now an encoding with no xvid options and increased bitrate, maybe it was compressed too much (also i cannot image a connection there).

ciao,
elm

[elm]

I'm running now an encoding with no xvid options and increased bitrate, maybe it was compressed too much (also i cannot image a connection there).


Well, same result, even with a high bitrate and no other encoding options the problem occurs.
Seems like I'll have to fall back to divx for this one.

Funny problem though.

Thanks for your help & ciao,
elm