Tmpgenc XVCD Edges

[tim12892]

I followed the help guide on this site to create XVCD (MPEG1) using tmpgenc (version 2.02 dated Dec 5, 2001) with 2500kps at a resolution of 720x480. However, the edges of video with motion seems jerky and has black horizontal edges on the moving subjects. The original AVI file looks fine with smooth with smooth edge on the moving subjects. Still images looks fantastics using the XVCD method but the motion ones are the problem.

I tried tweaking the kps, the "noise reduction", search precision. Nothing seems to work and I didn't find any posting of the same.

Can anybody help?

[kinneera]

This is an effect of macroblocks, albeit a less glaring one. You won't get rid of them unless you lower the resolution. A smoother of some sort won't hurt either.

[tim12892]

Thanks for the reply. However, even if I use the default DVD(NTSC) template from tmpgenc, I get the same result. Surely, that's not the type of effect seen on DVD? Anything I'm missing here?

[kinneera]

There are a lot of other possible causes, most importantly but not limited to your source material quality. Odds are you aren't working with a studio master of a film, so you're going to have a harder time matching commercially produced DVD quality.

Also, it sounds to me what you're describing is what is known as aliasing. In short, since computers use pixels, which are discrete units of length, diagonal and curved lines in particular will never truly be smooth. Think of it as drawing a circle using a whole bunch of very small straight lines. This is a common issue with all computer graphics, to which there are various partial solutions. Again, a smoother of some sort might work wonders for you, since they are designed to slightly blur sharp edges and reduce noise, both of which give MPEG encoders a hard time. In TMPGEnc, the noise reduction filter is really a smoother.

Finally, I would also note that sharp edges and line art (ie cartoons) are extremely difficult for MPEG at low bitrates. The well-known tradeoff with MPEGs is either more edge noise or more noise in areas of large solid color. (Cartoons have both in abundance, which do you choose? ) In general, though, a good rule of thumb is that TVs hide edge noise a lot better.

<font size=-1>[ This Message was edited by: kinneera on 2002-01-05 12:33:13 ]</font>

[KaBoNG]

Tim,

I ran in to something similar while encoding a DVD to XVCD last night. If it is the same issue, there are a few things you can try to clean it up.

First, try using one of the CQ (constant quality) VBR rate control modes instead of CBR (constant bit rate). The setting for this is on the "Video" tab. I used the automatic mode with a max bit rate of 2500.

Second, and maybe most important, under the "Advanced" tab, try using the Deinterlace filter. I used Method: Even Field and it completely eliminated the black horizontal "edges" if we are talking about the same thing. Just double click on it to bring up the setting window.

Please let me know if this helps.

KaBoNG!

[tim12892]

KaBoNG,

Eureka!! I followed your advise (CQ_VBR and Deinterlace) and it worked. The black horizontal lines are all gone and the video is as close to the original DVD as it could get.

Thank you very much!!

Tim

[KaBoNG]

Tim,

Glad to hear it worked for you. Kinda surprising myself as I only started into doing this myself last weekend.

BTW, it was a cartoon I was working on when I figured out these settings (re: Kinn's advice above that mpeg's have a tough time with cartoons).