kneal
22nd March 2002, 01:31
This will be a long post.
The first MAJOR problem that I'm having is a black line across the top of my divx5 movies made with XMPEG. After cropping the top of the movie well beyond the black letterbox area and even removing some of the movie, there still appears to be a black line. It can be easily verified by opening the movie with VirtualDub, and zooming to 4x. There should be only color, but the top pixel row is all black, and it affects the color/quality of the next pixel row as well (maybe more).
This seems to be an XMPEG bug, because uncompressed avi format exhibits the same behaviour.
Using the same crop values inside the DIVX5pro codec results in an avi without this black line, but the performance is hit hard! Here are the results of testing a 111 Mb clip. Not all variables are specific to this problem, but interesting nonetheless.
Quality based, 86% (q=6.0), Bframes, light preprocess (whoops):
1-all crop disabled, 720 x 480, 7.68fps, 8072 KB
2-xmpeg crop enabled, no actual cropping,
720 x 480, 7.60fps, 8609 KB (?)
Then crop most of black area using:
3-xmpeg crop, 640 x 276, 11.28fps, 7374 KB
4-divx5 crop, 640 x 276, 8.68fps, 7281 KB
Then crop out all black area and some movie using:
5-xmpeg crop, 624 x 272, 11.52fps, 6780 KB (black line at top!)
6-divx5 crop, 624 x 272, 8.57fps, 6648 KB (no black line, same values used!!!)
The black line appearing is almost enough motivation to learn GKnot, but oh well. The performance hit of ~25% is too much! I tried to work around by dual cropping- #3 above, and then trim the edge with divx5: 624 x 272, 10.83fps, 6624 KB, no black line! :-) I can take the 6% hit while I'm sleeping.
Regardless, now I have ~30 divx movies with a black line for the time before I noticed. :-/ Has anybody else experienced this???
A second minor problem I'm having is that the output avi has multiple almost identical frames between 13 and 19. It happens in scenes that are supposed to be contantly and consistently moving. Zooming in, I can see some pixels change color _slightly_, but the obvious movement is gone no matter which clip is chosen in XMPEG. I don't know what to attribute this bug to.
Well, other than possible artifacts in DIVX5 with non16x dimensions and VirtualDub not showing correct locations (use keyframe forward, then click "find next scenechange" and it jumps to the real frame), I'm done ranting.
I hope that the information above will be useful to somebody.
The first MAJOR problem that I'm having is a black line across the top of my divx5 movies made with XMPEG. After cropping the top of the movie well beyond the black letterbox area and even removing some of the movie, there still appears to be a black line. It can be easily verified by opening the movie with VirtualDub, and zooming to 4x. There should be only color, but the top pixel row is all black, and it affects the color/quality of the next pixel row as well (maybe more).
This seems to be an XMPEG bug, because uncompressed avi format exhibits the same behaviour.
Using the same crop values inside the DIVX5pro codec results in an avi without this black line, but the performance is hit hard! Here are the results of testing a 111 Mb clip. Not all variables are specific to this problem, but interesting nonetheless.
Quality based, 86% (q=6.0), Bframes, light preprocess (whoops):
1-all crop disabled, 720 x 480, 7.68fps, 8072 KB
2-xmpeg crop enabled, no actual cropping,
720 x 480, 7.60fps, 8609 KB (?)
Then crop most of black area using:
3-xmpeg crop, 640 x 276, 11.28fps, 7374 KB
4-divx5 crop, 640 x 276, 8.68fps, 7281 KB
Then crop out all black area and some movie using:
5-xmpeg crop, 624 x 272, 11.52fps, 6780 KB (black line at top!)
6-divx5 crop, 624 x 272, 8.57fps, 6648 KB (no black line, same values used!!!)
The black line appearing is almost enough motivation to learn GKnot, but oh well. The performance hit of ~25% is too much! I tried to work around by dual cropping- #3 above, and then trim the edge with divx5: 624 x 272, 10.83fps, 6624 KB, no black line! :-) I can take the 6% hit while I'm sleeping.
Regardless, now I have ~30 divx movies with a black line for the time before I noticed. :-/ Has anybody else experienced this???
A second minor problem I'm having is that the output avi has multiple almost identical frames between 13 and 19. It happens in scenes that are supposed to be contantly and consistently moving. Zooming in, I can see some pixels change color _slightly_, but the obvious movement is gone no matter which clip is chosen in XMPEG. I don't know what to attribute this bug to.
Well, other than possible artifacts in DIVX5 with non16x dimensions and VirtualDub not showing correct locations (use keyframe forward, then click "find next scenechange" and it jumps to the real frame), I'm done ranting.
I hope that the information above will be useful to somebody.