*SOLVED* Video constantly freezing then playing double-speed catch up

[PatPend]

Running latest version of BI with a mix of Grandstream and generic IP cams. One type of camera I got on eBay (yea I know) is giving me trouble. They don't stream smoothly into Blue Iris in either live view or playback, ever. The stream will freeze for 2-3 seconds and the next 2-3 seconds the video plays "catch up" in fast motion. The BI-generated timestamp freezes along with the image timestamp, and occasionally the BI timestamp jumps backward a second or two then catch up. The attached video clip demonstrates the issue.

I've tried many different combinations of settings, changed network switch, nothing helps. No issues with any of the other cams. BI is running in a VM (virtualbox, ubuntu host, W7 guest) at under 40% cpu with plenty of RAM. FWIW it's a dome camera listed as a "LEXA G5202 Infrared/Night Vision, Outdoor/Weatherproof, Vandal Proof, Image Sensor SONY 1.37MP IMX 238"

Any thoughts on how to troubleshoot this would be much appreciated.

thank you, Russell

 

[PatPend]

Unchecking "Use RTSP/stream timecode" helped a lot. The BI timestamp is still a little uneven but it's much better.