Horizontal Split Image after rendering

BigTGMyers wrote on 2/27/2005, 5:16 AM
Horizontal Split Image after rendering

When I render some of my projects to DVD movies the resulting MPEG gets an odd imtermitent horizontal split in the image. The image seems to be missing a few lines at the split and the upper half often has a slight increase in brightness. This seems to occur more often in regions of the video that have more motion.

Any ideas as to the cause and any fixes?

The original source video clips in my last project that produced this effect have the following video properties:
448x336x32, 25.000 fps, 25-35sec, Alpha-None, Field Order=None(progressive scan), MPEG-1

Thanks,

Tom

Comments

IanG wrote on 2/28/2005, 12:52 AM
I think the problem is caused by starting with MPEG1 - it's a lossy format and you're asking MS to add detail that isn't there, and then apply another lossy compression (MPEG2). You might be able to render from MPEG1 to avi and then use that, but I've never tried it.

Ian G.
BigTGMyers wrote on 3/1/2005, 7:25 PM
I did not recall asking MS to add anything! The issue of whether or not MPEG is a good format to use is not the issue here. What I am dealing with is the simple fact that the source is MPEG-1 and I want to compile these CLEANLY and burn them to a DVD (not a VCD) for ease in sharing them with friends and family.

I am hoping that there is a clean way to do this without the horizontal split in the image and without having to migrate through another format. If that is the only way then I want to do so without a loss in quality.

Thanks
IanG wrote on 3/2/2005, 1:04 AM
>I did not recall asking MS to add anything

Not explicitly, but that's what you've done. MPEG2 is a higher resolution than MPEG1 - the extra bits have to be created during the encoding to MPEG2.

>The issue of whether or not MPEG is a good format to use is not the issue here

I hope you're right, but I'm still betting against you :-)

Ian G.
Dave_D wrote on 3/11/2005, 9:29 AM
I have encountered this problem when trying to render a .wmv file from a divx .avi source file. If I render it as a 3mb/sec .wmv (640x480) the horizontal line occurs, however at 1mb/sec (320x240) it does not. It's annoying because a 3mb/sec .wmv file offers an excellent result (except for the horizontal split of course).

Does anyone have an explanation as to why this is happening? Is it down to Vegas' rendering performance or a generic problem to do with increasing the frame size?

One workaround you could use although not ideal, is to render to an uncompressed avi, and then again to mpeg for the dvd.