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Converting VHS to digital.

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I have a question.
Complete novice here, so please excuse my blundering description of what's going on.
I live in a Region 1 nation and have a PAL VCR, a Panasonic NV SD270 player. Pretty basic model, I know, but it plays NTSC tapes. I am converting tapes to digital, using budget software.
Well, when converting a commercial release NTSC tape I noticed a “pop” at the extreme bottom of the screen. I have worked in traditional animation and have a very good eye for discrepancies, color pops being the indicator of a mistake that needs correction. So I had a look. There was a small area of detail, which persisted for a fraction of a second and isn't a fault in the tape, so I played back the capture to see what it was.
I used a software player that allows me to step 24 frames second to view the capture. Here's the thing. The “pop” (sorry) consisted of an area maybe 20 pixels square, with 5 frames showing detail against a black background. but each time I captured the motion it displayed a different set of frames. Lets call them A B C D and E .
First try       frames A B C     E, displayed
Second try, frames A    C D E.
Where B was present, D never was. When B was absent D was always present.
I repeated the capture 10 times and not once did all frames display. Just a fairly even split between the 2 options. Frame D had a small area of black surrounded by a fainter shade. In some captures the black area presented as a black square rather than a smooth circular area.
Replaying the capture , there was no discernible difference between the action on the entire screen, it appeared to run smoothly every time. But a clearly discernible difference between the behaviour of this small area. my perception being the result of checking and correcting literally 100's of thousands of animation cels.
Capturing at 25 fps or 30 fps made no difference
I believe that this section of the movie was sped up from the original filming speed, at least 2 times.
Filmed originally on Sony Betacam and processed using After Effects.
So does my Pal VCR play NTSC tapes at 30 (nominal) fps or 25? 
Is the discrepancy due to the 24 fps stepping of a 30 fps capture? When the same thing happened at a 25fps sampling rate.
Am I wasting my life obsessing over such a small detail. Probably, but that's how I learn and I don't get out much.
A little help here please.
Ive also had bizzare results transfering NTSC VHS played on native PAL model players.
Even on more professional gear.

In the end a Panasonic VHS / DVD recorder combo a friend had, a off the shelf PAL model was by far the best results Id seen.
That had a option in the settings though to switch it between PAL and NTSC.
(This post was last modified: 2020-08-18, 09:50 AM by CSchmidlapp.)

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