What causes the picture to "bounce"?

[tdan]

I am doing some captures with the following:
JVC SRV10U ->S-video -> AVT8710 -> S-Video -> AIW 9700pro

With some, not all, tapes, the whole picture occasionally bounces up and down a few scan lines then re-stabilizes. My question is: what causes this sort of problem? Does it have a specific name?

Is it damaged tape? Or, is there something with the VCR?

Can something be done about it?

Thanks,
Dan

[Cole]

In my experience, tapes will play differently in different VCRs if there is a problem with it.

This could happen however at the beginning of a tape as the VCR is adjusting its tracking and then it will be okay for the rest of the tape. Is this jitter running through the whole tape?

I am not sure what the actual cause is, but having a VCR with a picture stabalizer would probably help in the situation that you describe if it is indeed the whole tape.

[tdan]

OK, so now I know what "jitter" is
Is this generally a tracking issue? On this tape, it occurs through the whole tape.

On the JVC, I noticed that if I turn off the TBC/DNR, then the problem goes away, at the expense of a much noisier picture.

I am going to try a different VCR and see if it can handle the tape better.

Dan

[pijetro]

Just read my Panasonic 1980P manual..
The booklet says to turn of TBC if there's vertical jumping..Do you have an adjustment for sharpness??

Did you try different combinations eith your VCR/TBC setup? Whatabout a bypass on the AVT8710??

[Cole]

On the JVC, I noticed that if I turn off the TBC/DNR, then the problem goes away, at the expense of a much noisier picture.

Sadly, the picture stabaliser (if your JVC has one) can not operate at the same time as the VCR's TBC/DNR. Also the VCR's TBC can be the cause of the playback error, such as this or tearing at the top of the picture.

[lordsmurf]

The stabilizer and TBC/DNR can cause jitter. Try it with them off. Also try to turn the unit into EDIT mode, which disables the picture filters.

Some tapes are just crap. Do the best you can.

[tdan]

Thanks for all the input. In the end I just went with the noisier picture by switching off the TBC on the VCR.

It's the only tape that behaves this way, so I am just lumping it in the "crap tape" category.

Dan

[pijetro]

Since your using ATI software, perhaps a small amount of video soap might be just what the doctor ordered...

[tdan]

Yeah. I played around with the video soap a bit. I wish I could make the preview window bigger (i.e. 720x480, the capture resolution). It was impossible to tell what effect (good or bad) that my soap settings were having.

When I have more time, I will need to do a bunch of test captures with soap to see how much to use (and which filters) without creating bad artifacts.

Dan

[rbatty11]

I'm curious if Deshaker filter would work on the jitter in question..?? Does anyone know? I know it's to be used for unsteadiness/movement of hand-held cam recordings but was just wondering..