Quantcast What an Ideal TBC would look like on VHS - digitalFAQ Forum
07-22-2012, 05:52 AM
jmac698 jmac698 is offline
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Here's an experiment I did. I recorded a test signal on VHS and used a mathematical formula to align it perfectly upon playback, in a way that was completely independant of the equipment. The resulting video is absolutely stable, except for a few glitches where the line jitter exceeded the algorithms settings.

There's one more trick involved; in this version I've recorded 3 passes of the video to simulate a component signal, that's why the colors look so good. You can only judge the horizontal stability and the background noise with this sample.

However, if for some reason you really wanted to record onto VHS with modern technology, you can achieve these results for real-time recording and playback from VHS. I could build a $30 device out of a Rasberry Pi PC, for example, that would just plug into the VCR to enhance it's abilities. The resulting tapes would be compatible with any machine, however you would see the test signals in the borders without the attachment.

I know this is completely useless, however it's purpose is to measure the actual line jitter of VCR's and how well TBC's work. Once I put this all into a plugin, I'll be able to do a complete analysis of any system instantly.

I should also note that there was head-switching "noise" at the bottom - now removed, since I placed those "random" lines where they were supposed to go You don't have to crop head-switching noise any more!

This could've been made into an electronic circuit, if I were in the right place at the right time 20 years ago, I could've patented it and we'd never need a TBC today

Attached Files
File Type: avi Ideal TBC experiment.avi (2.21 MB, 51 downloads)
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