As a way to contribute to the livestreaming community, in particular the members of the vMix user’s forum, we offer you some insights concerning a pretty new device for capturing video to a PC via USB3. At the same time, for WestreamU’s customers, this blog post illustrates how we go about in order to assess new technology. Always with the ambition to provide smart, cost effective and beautiful live productions.

Quick summary: The Yuan box is really interesting, works better than we expected. On the one hand, it’s H264 compression affects the video quality. On the other hand it’s a neat way to get 4 SDI inputs (or other combos) via USB3. Main limitation is that it might require a lot of CPU power for decoding. So, if you are thinking of a portable laptop-based solution, this box may not be the solution. Mind also that the resolution and frame rate affects the delay from camera to mixer. Watch the videos, follow the related links, read our lab report and the comments from Yuan and vMix.


All videos shown here was produced live at WeStudioU using vMix (v16). We tested the Yuan UB5A0N4 Hybrid, kindly lended to us by their Swedish distributor JMC Systems Engineering. In addition we compared it with the Magewell XI100DUSB-HDMI (discontinued, replaced by another USB device), and the Yuan SC510N4 HDMI.

Lab report

We did not receive any manual/instructions, besides a quick installation guide. The UB5A0N4 Hybrid has four SDI ports, one Composite/S-Video/YPbPr, and one DVI/HDMI/VGA. We installed the DRIVER.QP0204_YS downlaoded from Yuan’s web site. vMix (and Windows’s device manager) recognized four devices, assumingly the SDI ports. After the tests we learned that the device driver for the fourth (SDI) port can optionally be set to use DVI/DMI/VGA instead. Thus letting you have 3 SDI + something else. [Update: Yuan later informed us that the the green connector is RS485 for controlling PTZ camera].

We did all with the same preset setup for vMix (Win 8.1), and all recordings made to 8 mbps MP4 @ 50p (yeah, bad choice of frame rate for the 25p tests – sorry). The Input for the Yuan device was set to use the H264 Low latency video. Camera Canon Legria XA25, SDI out. The SDI-cable was split to SDI and HDMI, former to the Yuan box and latter into the Magewell USB dongle.

First test video was made on an underpowered Asus UX302LG, render time around 25ms, vMix CPU around 70%. Using built in Intel 4400 HD Graphics (don’t know how to make vMix use the Nvidia GeForce GT 730M 2GB). Master set to 720 25p, recorded 720 50p. Camera set to 720 50p. We unfortunately had the camera on autofocus, but I think you can guess when focus is lost, and when the image is slightly unsharp during movements.

Then some test using an Asus G750. Render time a few ms, vMix CPU around 15%. Using its Nvidia GTX 865M card. We also set camera to fixed focus.

Second test video: Master set to 720 25p, recorded 720 50p. Camera set to 720 50p.

Third test video: Master set to 720 50p, recorded 720 50p, Camera set to 720 50p

Fourth test video: Master set to 1080 50p, recorded 1080 50p, Camera set to 1080 50i

Clearly the Yuan UB5A04N video delay increases with increased resolution/frame rate.

Noticing that the Input from the Magewell USB dongle was not very good in the fourth test, we removed the Yuan and recorded it alone with the fourth’s settings. Still not so good, but we don’t use that dongle for Full HD anyway so we just left it there.

Fifth test video was to hook up one camera via some splitters/converters to feed it to all four SDI ports on the Yuan box. We also retained all settings and resolutions from the fourth test. Important to note here is that the vMix CPU usage went up to almost 60%. (We also tried with 720 50p, same CPU load no video on that).

Finally in the sixth test video we did a quick recording by converting the SDI signal to HDMI and feeding it to one input of our SC510N4 HDMI PCIe-card. Just to compare the image quality with that of the Yuan.

Brief comments from the manufacturers

Yuan and vMix both received the information above (except the unboxing video which we hadn’t recorded yet).

Yuan then did some tests on their own. Using their QCAP testing program they found much lower CPU usage, compared to when video was captured using vMix. They also confirmed how latency varies with video settings. See table below (source Yuan).

Yuan UB5A0N4 latency test

The developer of vMix, who also got Yuan’s table, comments: “vMix uses the CPU for decoding the H264 inputs as using the GPU decoding interferes with the rest of vMix which Yuan are using with QCAP. However, the CPU usage isn’t very high when using a suitable processor, it was not significant when using a 4790K 4GHZ for example”. And, after a follow up conversation, “I may look at using the Nvidia GPU decoding in a future release as that doesn’t interfere as much with the GPU as the Intel one does”.

If you have any technical comments/questions, please consider posting them in the vMix user’s forum topic concerning UB5A0N4. Of course, replies to this post here is always welcome.