Sabrent USB-AVCPT capturing Nintendo 64 - whole screen scrolls continuously

[Irrelevant Speedrunner]

Hi there. I've been Googling furiously and not finding this problem even described anywhere, so I thought I'd ask. I just got a Sabrent USB-AVCPT (Easycap clone) to record Nintendo 64 gameplay. I was able to get the driver installed and get a good picture with minimal artifacts, except for one thing - the entire picture keeps scrolling down slowly and continuously, with the bottom edge disappearing off the bottom of the window and simultaneously reappearing from the top. I tried it with both Virtual VCR and VirtualDub, and it happens both in the preview window and in the finished .avi video file. I also tried two different inputs - from my CRT TV (N64->TV->Sabrent), and directly from the N64 (N64->Sabrent). Is this a driver problem, or just a defective unit, or something else? Your help is much appreciated.

[Brad]

For N64 capture you need a device capable of capturing "240p" input. I believe some of the Easycap clones support this, while others don't, depending on the actual chipset used.

https://kb.speeddemosarchive.com/New_Recording_Devices#Capture_Devices_List

Amazon review complaining of 240p problem

[Irrelevant Speedrunner]

I believe this is one of the units that does support 240p. Also, I tried it this morning with a VCR as the video source instead of the N64, and the scrolling problem was gone (although there were different problems with the picture). Could this be due to a weak composite video signal?

[Brad]

I believe some VCRs generate 240p for full-screen menus. What happens if you hit the Menu button?