MACROVISION brightening and fading!! help!!

[tomasine17]

Hello everyone. I just purchased a JVC HR-7800u vcr with a built in TBC. I also use an ATI AllInWonder 8500DV to capture with, and Virtual Dub file capture software instead of the ATI software. My goal was to bypass macrovision on a tape I have, and to record it from my new vcr with my ATI card onto my comp.

Upon playing the tape from the new vcr, I see that indeed the macrovision has been bypassed, but unfortunately a side effect has arisen, that being that the when playing the vhs tape, the picture will darken for about 10 seconds, and then brighten back up again to normal for about 10 seconds, and keep repeating this pattern over and over. This pattern keeps alternating. Amazingly enough, the outputted picture to the tv does not do this. The picture is only displayed this way through the vd capture software, or the ATI software. So basically, this happens after the video has been transmitted either through s-video or composite video to the computer. I've tried s-video and composite and it happens both ways. I've also tried using an older vcr and using the ATI patch for disabling macrovision on the video inputs of the ATI card, and that still produces a picture with this brightening and fading.

Has anyone come across this or know of a solution? Thanks for the help!

[kimomakano]

I believe that is another function of Macrovision. I have experienced the same thing and have been told the only way to bypass it is to either rip apart my VCR and modify it, purchase a de-macrovision unit, or use a TV that has RCA jacks for A/V output.

[Comberman]

Macrovision is a security system used on commercial pre-recorded VHS tapes to prevent copying. It affects the Autoutomatic Gain Control (AGC) circuitry in VCRs. In the Macrovision system new signals are inserted in the unused portion of the tape which fools the VCRs AGC into believing that the picture signal is too bright. It then compensates by darkening the brightness until it thinks it has the correct brightness. Of course, now the picture is too dark because of this "misconstrued" brightness. The Mvision signal changes periodically (about every 10 seconds or so) and so the VCR circuitry is forever trying to compensate this regular brightness/darkness. The reason why it is not visible on TV is because TVs do not have AGC. I believe the Disney Corporation where the first to use it. This is a simplified description of what happens with Macrovision, but I hope it explains what you are faced with.

You can get around Mvision if you are prepared to doctor your VCR - the problem is that you are more than likely going to render it useless for working with non-Mvision tapes. You can buy eliminators, (don't ask me where!!) or you can make an eliminator (don't ask me how!!) if you are handy with a soldering iron and no a little about basic electronics.

Cheers