Field jumps when capturing with AVT-8710 TBC

[barakori]

Hi,

My setup is as follows:

VCR -> AVT-8710 TBC -> Director's Cut -> Computer

(BTW, I'm capturing PAL)

I used to have "dropped signal" problems before buying the TBC, which I got a few days ago. Now, I always have frames, but sometimes a strange vertical error occurs. One field is has an extra line at the top, so if the original frame had lines 1-10, the captured frame seems to have the lines in the following order:

-,2,1,4,3,6,5,8,7,10,9,...

This results in a really distorted frame. It's most visible with static text, but it's noticable in maybe other diagnal lines and more.

Now I don't get it throughout the capture, just every once in a while. Has anyone ever seen such anomaly? I think the AVT-8710 is supposed to handle vertical synch...

I've put out two consecutive frames to show the anomaly. The first: http://www.xmixdrix.com/frame-224.gif is fine, the one after it: http://www.xmixdrix.com/frame-225.gif is distorted. Notice the static text (Sorry - Hebrew) and the light switchs on the right hand side of the image.

Another option - take a look at an animated GIF of the two frames: http://www.xmixdrix.com/frames.gif.

(BTW, I used GIFs to better preserve the interlaced nature of the image. I think JPEG would have resulted in better colors, but would also soften the differences between the fields).

I'm using a good VCR (6 heads JVC) and a good tape, nothing too old. Any help would be greatly appreciated.

Thanks,

Barak

[mustardman]

This is PRECISELY the problem I have been experiencing with my captures, using a miro pinnacle DC30+ (although quite old). A friend uses a DC10 (6 months old), and he has the *same* problems.

I thought it was just my tapes, but maybe it is not...

Sometines a TBC can fix it, other times it won't. Looks like your TBC can't always fix it.

I have been trying to fix this problem for over a year now, and I am finally getting somewhere with the help of a VERY generous programmer who has written an application that can take the bad video file and basically generate a good file from it. And I must say it works exceptionally well, although it is not _quite_ finished yet...

I will pass him the info on this thread, and he may be inclined to get you into the loop.

I have not found *any* way of fixing this problem before capture (ie: hardware processing of the video signal), so this software is a real beaut! I have tried 2 different TBC, 4 different VCRs of various age & capability (4 head/2 head/Hi-Fi/new/old) and a 'stand-alone' sync regeneration device. Nothing wanted to fix it.


MustardMan.

[barakori]

@mustardman: Did you have this problem without using a TBC? I saw it for the first time when I used the AVT-8710, never before that (Maybe I was noticing other things). I used to capture video with my DC30+ with no problems. It just wanted to move to the easier DV format.

[mustardman]

Yes... I originally tried a TBC as I read on these forums that it could fix bad signal problems. However, this problem was occuring before on a straight VCR signal (both composite & S-video).

Another freind has a VCR with built in TBC, but it only plays HI-8 tapes. I haven't had any problems with his VCR, with the TBC turned on OR off.

As the card gets older, it seems to be exhibiting this problem more and more. I suppose it is about 5 years old now - it was purchaced when PCI was really new and CPU speeds were about 150MHz (that's slow man!).

As I doubt if I can get a circuit out of pinnacle for this card, I have to resort to trickier means to fix the problem. It was a *** expensive card when I bought it! But then again my other friend with the DC10 had experienced a similar problem with his *new* card. Go figure. It wouldn't surprise me if pinnacle used some dodgey analog sync separator, rather than a digital one.

If I had to buy another capture card, it would NOT be a pinnacle!

The same guy with the DC10 eventually got sick of it's cantankerous behavior (driver not working properly, field swapping problems, etc) and bought a cannopus ADVC100. I have checked it out, and it is really an excellent device (it is external!!). However, it's horizontal sync lock-on is not as good as the DC30. But it is great on the vertical sync, and considerably better than the DC30.

If you buy a new card, get one of these!!!

[barakori]

I'm not using the DC30+. I'm now using an analog to DV external box (like the ADVC100) called PowerR Director's Cut. It has good quality, but it can't capture too good from a VCR, so that's why I bought the TBC, but now I have this field jump error (with the TBC).

[mustardman]

I therefore assume that you intend on continuing to use the PowerR device, therefore also continuing to use a TBC.

I can't think of any method of 'fixing' your problem before it occurs, as the signal from the TBC would be clean and tight, but just plain wrong.

This application I talked about can fix the problem after it occurs, but that doesn't sound like what you want to do.

I also have a small gripe about TBCs - what is your experience...
When a frame is dropped, I *want* to know about it, so I can then take some action (re-capture, or just know about it). However, a TBC will (like you say) always provide a good frame to the capture card, but IF the signal input to the TBC causes *IT* to drop a frame (or repeat a frame if you like) then how are you ever going to know about it?

(PS: I really hate dropped frames!)