MPEG 2 image problems

argray wrote on 11/4/2002, 1:22 PM
I hope this is not a recently addressed issue, but I haven't seen any posts that discuss it.

When I render DV (captured from a Sony Digital Camcorder) into MPEG-2 format for burning to DVD, I often get an unpleasent video effect. The problem is in uneven horizontal "rows" as though someone dragged a rake sideways across the image. It's most noticable in high contrast areas of a smooth curve in motion: for example, a blue-sweatshirted figure might have a shoulder that looks almost like a saw-toothed edge. I would describe it as pixelization, yet the deformations are many times greater than a single pixel.

This problem persists whether the clip is played from hard disk or burned to DVD and played on television. On the other hand, the same captured AVI rendered to AVI and burned to DVD looks great. For hard disk space reasons, of course, I'd like to loose the AVI in favor of MPEG-2.

I can't find any updates to the codec, which is where it seems the problem would lie. Any suggestions here would be greatly appreciated.

-- Andrew Gray

Comments

SonyEPM wrote on 11/4/2002, 2:17 PM
sounds like maybe your DVD app is re-encoding. What DVD app are you using?
ralphied wrote on 11/14/2002, 10:27 AM
Rendering DV AVI files to MPEG-2 is as much an art as it is a science. There are so many options and settings in a MPEG encoder program it's mindboggling. If you bought the $29.95 version of the VF MPEG encoder add-in, you don't has access to all of the various settings, but they're there. VF had to weigh render quality against file size to come up with the settings hardcoded into the encoder.

But, like any piece of software, some MPEG encoders are very good and some are not so good. My experience has been that the MainConcept MPEG encoder used in VF is mediocre. It does a reasonable job for a reasonable cost. But, it certainly is not the best. I have found that the TMPEGEnc encoder, which costs $48, gives you more for your money. It's default MPEG-2 encoding setting (referred to "constant-quality @ 65%") produces excellent video quality (very close to the original DV AVI file) of modest file size. I can fit approximately 1.5 hours of video on a DVD. And, if you use Ulead's DVD MovieFactory software to author the DVD, it will not spend time re-rendering any portion of the MPEG-2 files, unlike some other DVD authoring software products (such as MyDVD.) TMPEGEnc also has a nice feature that MPEG renderings can be easily batch processed. This is convenient because you can set up all of your DV AVI files to be rendered overnight while your sleeping.


argray wrote on 11/16/2002, 11:35 AM
I appreciate the thoroughness of your response. I have download TMPEGEnc and will give it a try. I really think VideoFactory is a fine product, but am disappointed in the performance of the MainConcept MPEG-2 encoder. Life on the leading edge, I guess.
black_sunbeam wrote on 12/4/2002, 11:12 PM
how did the TMPEGEnc program work out? I'm getting the same video artifacts you described and I'd like to avoid them. Interestingly, they don't happen when my source AVI files are in lower resolutions, like 352x240, only when I'm using 720x480 source files.
Saturn49 wrote on 12/6/2002, 2:49 AM
Sounds like you both are having problems with field order. I think VV is supposed to auto-detect the source field order and encode with the same order, but I think it doesn't work properly on some sources. I know on my renders I have to manually specify Interlaced-Top Field First for my videos to look good on a televison. Bottom field first looked aweful, and everything was jumpy. Progessive only was better, but still not good.

Try a render with all three settings and see how it turns out.