One area of Linux hardware testing I haven't explored much in many years has been modern USB video capture for the lack of said hardware. The last time I did much video capturing on Linux was during the Hauppauge PCI card days. It turns out though that USB video capture of 4K 60 FPS content has been a pain point under Linux but is finally smoothing out with newer versions of the Linux kernel.

Phoronix reader Johannes Brüderl wrote in about the situation and how it's now changing due to a new quirk path within the Linux kernel. He explained that it's been "extremely complicated" handling 4K 60 FPS video capture with PCIe card support being spotty due to typically lacking Linux drivers for most hardware or otherwise being reverse-engineered. With USB devices while it typically works fine with UVC, there has been USB video capture card issues experienced if trying to achieve 4K 60 FPS recordings.

4K USB video capture cards on Linux have typically been falling back from 10 Gbps bandwidth to 5 Gbps bandwidth, which is enough for 4K @ 30 FPS but not 4K @ 60 FPS.

Back in Linux 6.19, Johannes Brüderl contributed a USB_QUIRK_NO_BOS quirk path for the Elgato 4K X due to the USB capture device hanging on BOS descriptor request and then falling back to 5 Gbps. With this quirk, the card stays at 10 Gbps operation and can capture 4K @ 60 FPS.

Since then other USB video capture cards have found to be in need of the same quirk such as the AverMedia Live Gamer Ultra 2.1, ASUS TUF 4K PRO, UGREEN 35871, and EZXCAP401. For those interested in USB video capture of 4K 60 FPS can find more details on the situation and quirk via this blog post. If you have one of these devices, you should be in good shape if using the latest upstream Linux 7.1 kernel or it's also possible your USB device may need this quirk too.