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Old 10th October 2011, 16:42   #12  |  Link
jmac698
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Join Date: Jan 2006
Posts: 1,867
sven,
That was incredible! I know this has been tackled many times, but I believe it's the first time there's been an analysis including the hidden area of hsync. It's very inspiring to me. However I can do a better job in making examples. I should record a test signal which is easier to line up, then we can measure directly the stretch/offset. My only concern is that the result won't be as bad as this tape. I picked this tape initially because it is a well-worn kids movie and showed massive jitter.
Does anyone know how I can make a tape with *bad* jitter? Perhaps if I copy many generations?

I had already felt that something was inherently wrong with lining up just by the left edge. People thought it failed because of their line-up algoritm (due to noise, etc.), but I had thought of the possibility of tape stretch and/or slight variations in head speed causing the line-stretching effect. In this case there's bad news, because I can only capture hsync once per line, if I capture the next hsync then I've missed the hsync for the next line and essentially never get any more lines.
Why that line is not good for lining-up is confusing to me however.


Last edited by jmac698; 10th October 2011 at 16:46.
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