Recorded video artifacts

When viewing the recorded programs on the PC I can see a line or two at the top that looks completely garbled, like random data. Of course you can’t see it when viewing on TV since they overscan by some percentage so those lines get clipped.
I’ve observed it on almost all DVD recorders I’ve tried (Liteon 5006, Memorex 2002, Govideo VR1940, Coby DVD-R1200) with the exception of Magnavox MVDR-660. Some of them use LSI, some Mediatek chipset.
I wonder if those are the scan lines with the other encoded info in them (aka data lines like cable encryption, station information etc.) However I don’t see those consistently on all channels.
Anyone have any idea what those lines are? They are pretty annoying when viewing on PC.

This is perfectly normal if your source is from VHS or 8mm tapes… This is head switching noise and is present in the overscan area of the video… This part is completly invisible to a standard TV and you should not worry about it… It has nothing to do with the encoding chipset…it’s part of the original signal. Some capturing software use clever methods for CROPPING OUT that area.

This does not apply to live TV, DVD or MiniDV sources.

You can see this for yourself by plugging your VCR directly to an old TV set with a vertical hold knob, a slight turn of the knov to roll the video and you will see this same noise.

The noise (white dots) you see at the top on some signals is the vertical blanking area, usually time code information but normally you never see this anyways.

This was on the live TV recordings , not VHS. MiniDV over firewire does not produce those artifacts.