I’m trying to connect my video source to PC. Video source is 1920x1080 60Hz. When I plug in Epiphan DVI2USB to a USB3.0 port, everything works perfect; but when I plug it in to USB2.0 port, the image on Epiphan Capture Tool stutters a lot, FPS decreases to 5-6.
What could be the reason to this?
That is actually completely normal, USB 2 has a much lower bandwidth capacity compared to USB 3 and this causes the framerates to be lower.
I need 1080p 30 fps or 720p 30 fps. Is it not possible via USB2.0? Because I’ve seen 720p-30 fps before with Epiphan plugged in to USB2.0
You can get about 10fps over USB 2 normally. It is possible to increase this by increasing the amount of compression over USB 2, this would be under Capture -> Configure Device -> Advanced. The higher the compression setting here, the higher your framerate will be, but as a tradeoff there will be increasing levels of compression artifacts in the video.
But how do you think I got around 30 fps before with usb2.0? (Same PC, same video source, same epiphan, same cables)
The framerate will also change with the incoming video signal’s resolution. The lower the resolution the higher the framerate will be. If you were capturing from a standard definition signal then it may well have been at 30fps even with the default compression setting for USB 2.
it was from a 720p resolution video signal.
Ok, that must have either been a USB 3 port, or USB 2 with a high setting for compression.