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Video Engineer? Help! Betacam SP gets flutter at top when xfered to DVD

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arthouse
Video Engineer? Help! Betacam SP gets flutter at top when xfered to DVD
on Nov 17, 2005 at 2:17:08 pm

Sorry for a dumb question, but I'm more of an artist than an engineer. If you are really into video signals, can you help?

I'm trying to lay off my old betacam SP library to DVD for personal archive. Some of the betacams were created from 3/4" or VHS sources.

I've used several different off-the-shelf stand-alone DVD recorders and usually end up with the following bad result:

The top 2-5 percent of the newly recorded DVD-R has a fluttering artifact. The rest of the picture is perfect. Is this due to the fact that betcam is 640x480 or is it something else. The artifact kind of looks like screwed up VITC or bad blanking or something.

Is there any piece of relatively cheap gear I can insert between the Betacam and the DVD recorder to eliminate this problem?

Your help would be greatly appreciated.

-arthouse


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Mark Suszko
Re: Video Engineer? Help! Betacam SP gets flutter at top when xfered to DVD
on Nov 17, 2005 at 8:15:27 pm

Can you describe your complete signal chain (path)? Is there a time base corrector or proc-amp in there anywhere? If these terms sound alien to you, I think we may have found one likely source for the problem. There could be others.


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arthouse
Re: Video Engineer? Help! Betacam SP gets flutter at top when xfered to DVD
on Nov 17, 2005 at 8:51:29 pm

Hi Mark,

Thanks for getting back to me. There is no tbc or proc amp in the line. The betacam is hooked directly via s-video cable to the dvd recorder. On almost all tapes that originated on betasp, there is no problem at all. But it seems like betacams that had been originally created from a 3/4 or VHS source have the strange signal artifact at the tippy-top of the frame.

Oh yeah, and one more important thing...

This artifact never appears on a standard TV when played back from the DVD-R in a standard DVD player, but the artifact becomes present when viewing in a computer or miniDV camcorder.

What'd ya thinK?


-arthouse


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Mark Suszko
Re: Video Engineer? Help! Betacam SP gets flutter at top when xfered to DVD
on Nov 17, 2005 at 9:28:34 pm

Well, you could have recorded the head-gap-switching from the older tapes onto the beta. (scratches head) Can't remember how many lines each format gets you. Perhaps you are not seeing it in other places because your monitor doesn't underscan? Have you looked at a sample of all of these tapes on a real broadcast monitor with cross and underscan? Not just a regular TV? My gut tells me all the same sources will have the same problem. You could mattte it out if you ran it thru a switcher, or DVE the screen a few lines worth and re-center it. Some dubbing systems add lines with each generation, as does closed-captioning... well, that's not *exactly right, cc puts information on line 22, you can see little white boxes flickering in and out of existence if your monitor allows looking at the VBI.


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tony salgado
Re: Video Engineer? Help! Betacam SP gets flutter at top when xfered to DVD
on Nov 21, 2005 at 5:34:54 am



Yes it is head switching which you are seeing.

3/4" and VHS all had head switching which would have showed up in any dubs.

In addition it was essential that the original dubs to betacam were done using a TBC for the 3/4 and VHS machine.


Masking the head switching as Mark suggested is the first solution short of redubbing the original footage.


Tony Salgado

Tony Salgado


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arthouse
Re: Video Engineer? Help! Betacam SP gets flutter at top when xfered to DVD
on Nov 21, 2005 at 2:05:03 pm

Wow, thanks guys! Sorry it took so long to respond but I was out of town without the computer.

It feels so good to know that there is a name for my problem HEAD SWITCHING! I went and bought a Horita matte generator thanks to your input. Let's see if that baby will do the job.

I really appreciate your help!!!!!!!!

The mattte gen. will be here in a couple days and I bet we'll be set.

Cheers,

- arthouse


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Chuck Reti
Re: Video Engineer? Help! Betacam SP gets flutter at top when xfered to DVD
on Nov 23, 2005 at 4:31:21 am

[tony salgado] "it is head switching which you are seeing.

3/4" and VHS all had head switching which would have showed up in any dubs."


Doesn't head switching usually occur near the bottom of the frame, a few lines before V blanking interval?. Flagging or skew at the top is usually the result of tension error or transport problems due to misadjusted or out-of-alignment guides or other mechanical issues. Since the flagging or head switch artifacts are dubbed into the Betas then masking it off may be the best and only workaround. Since there was no TBC or proc on the Beta output, it's also possible that sync/blanking out of the Beta is distorted/jittery and maybe just stable enough for a monitor to lock onto but not other video devices that require tighter sync.


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