Analog conversion is done with S-Video directly into a digital imaging Matrox VIO card card. I do the following tapes: VHS, SVHS, VHS–C, SVHS-C, Video8, and Hi8. All analog conversion is done using S-Video at 640x480 through BNC connectors. The loss of sync you're referring to is from the customer turning on and off the camcorder going through different video clips.
All VCRs are commercial SVHS VCRs Panasonic 1970 and even on eBay sell for $500 used today.
Some customers even switch between SP and LP mode between these video clips.
The original unstabilized video is one hour and 21 minutes in both unstabilized and Windows 7 stabilized. However, under Windows 10 stabilized version is 5 hours and 16 minutes.