Cleaning Up Weird "jittering" in the background

[cfelicio]

Hi There,

Anyone know if it's possible to clean up the background of this video? It is more obvious between 8 - 9 sec timeframe (door texture in the backgrounc). The camera shakes a bit, but feels like the texture didn't.

Please let me know if you saw this before and know how to improve it!

Thanks!

[jagabo]

That's the result of too much temporal noise filtering. Do you have an unfiltered version?

[cfelicio]

unfortunately not, this is the capture. I also have the original VHS, but it is a couple of thousand miles away. I guess no way to improve?

[jagabo]

Other than going back to the source and recapturing with lower noise reduction settings I don't know of any way to fix that.

Real time temporal noise reduction filters work by averaging together pixels from the current frame and several previous frames. When the differences are very large they don't average because it's assumed something moved -- averaging those pixels would blur the picture or give a multiple exposure look. So areas of low contrast detail are an average of the current frame and several frames earlier, high contrast details are from only the current frame. That end result is that low contrast areas move more slowly than high contrast areas.

[sanlyn]

I vewed the MPG on an LCD and a CRT. Looks like the blurries are cut down quite a bit on the CRT, so I'd suggest that some of it is typical of the inferior way LCD's handle motion, especially if you have a "slow" processor. Some AviSynth and VirtualDub temporal filters handle that kind of movement and noise a little better than others, but it's difficult to say which ones would work better without some trial and error.

[cfelicio]

Thanks for the info! So in this case, you think even recapturing wouldn't help? I noticed the other videos also have some of this, although less noticeable.

[jagabo]

What are you capturing with? Turn off the noise reduction and capture again. Then do you filtering in software where you have better control.

[cfelicio]

I captured with an ATI 550 and Virtual VCR, I think the only thing enabled was the 3d comb filter. But it went straight to mpeg-2 (8000kpbs), maybe that's what introduced the artifacts?

[jagabo]

Yes, poor Mpeg 2 encoding could cause that.

[sanlyn]

jagabo is right. The only way to see what the original video really looks like is to capture to AVI without filtering. You can use a proc amp in circuit to correct color/levels if necessary, but a video source that requires any level of further correction should be in AVI without filtering.