Screen shaking

[RFontenot]

I've notice a problem with some of my VCDs where the entire screen "shakes". Usually it's up and down, but sometimes side to side. The amount of shaking is measurable if there is a straight line near a screen edge.

It's not a lot, just a couple of lines or so, but it's enough to give me a headache after watching it for a few minutes on a big screen.

At first I thought it was a source video problem, as I first noticed it with some children's video tapes I converted from VHS to VCD. However, I noticed the same problem on some of my DVD to VCD conversions, where I know the source was flawless.

I use TMPEGEnc v2.02 and DVD2AVI 1.76 for most of my conversions. Anyone else run into this problem?

[Douglesh]

Use floating point DCT, that is exactly what its for, to stop shaking

[vitualis]

@ Douglesh: ?????

@ RFontenot: are you sure it isn't a hardware playback issue?

Regards.

[RFontenot]

vitualis,

Actually, the shaking is on the original source. I took a real close look at one of the children's videos and I could see the shaking occurring even in the video.

I guess when they were telecining the original film, the film guides and sprockets must have been worn. As for the DVD, it was an old black and white movie from the '40s, so it may be the same problem.

I guess it's one of those things I never really noticed before, but once I did, I couldn't stop noticing it.

As for using floating point DCT to reduce shaking, is there any reference to that? I couldn't find anything about it being used for that.

RF

[vitualis]

I don't see how floating point DCT could have anything to do with reduction of "shaking"...

If this was in the source, I will have to say I do not know what you can do about it... Perhaps someone else will have an idea.

Regards.

[kinneera]

This might also be an effect of interlacing. The alternation between slightly offset fields is noticeable to the discriminating eye in some circumstances, especially when sharp horizontal edges or text are prominent in the video. It's quite possible that it also gets worse on older tapes. A deinterlace filter may help. If you see this effect even with inverse telecined video, however, it may be simply a function of how your DVD player converts frame-based video to field-based for playing on your TV.