Capturing video from a Digital 8: why does the video look funny?

Question

I'm using a Sony TRV330 to get my old Hi8 cassette tapes transferred to my computer for editing later on. but whenever I play them back, why is there a funny looking line at the very bottom of the picture? I don't know what the technical term for that is, but it's a squiggly line that looks like a warp in the tape or something. it's on every single tape that I've transferred so far. is that just a part of what you get when you convert analog video to digital, or is there a way to avoid getting that when capturing video to the computer?

Answer 1

It may also be the vidicon in the cam

Answer 2

that line is an artifact of analog tape reproduction. the video playback head comes in two parts, 180 degrees apart. the tape wraps half-way around the drum, so at any time only one of the spinning heads contacts the tape.  the line is the point where one head hands off to the other head (called head switch in the trade). in professional gear, the head switch occurs in the vertical interval where it can't be seen. in consumer players the switch occurs where it is just visible in the lower part of the picture. this was done intentionally to allow the user a visual reference to adjust the play tension (called skew) manually. After about 1985 both manual skew or tracking adjustments were eliminated from players and the tracking was corrected digitally. Tracking is only adjusted on analog tape, not digital, so it is possible the TRV330 does not allow user tracking adjustment, even when playing Hi8 tape. There will always be a slight mis-tracking when playing a tape that was recorded in a different camera. If it bothers you too much, you can cover it with a "letter box" black bar in your editor so that it is hidden.