At present, virtual reality headsets connect to Windows PCs through a combination of HDMI and USB cabling. That’s set to change in the near future, with a new agreement to use a single standard USB-C cable.
USB-C isn’t really just one standard. It’s an amalgamation of capabilities and features that are collectively grouped under a single reversible cable standard. This hasn’t been a universally good thing — in fact, there’s been quite a bit of confusion and improper standard support around USB-C as a result of this decision. At the same time, the entire reason why the new VirtualLink open industry connectivity standard can exist is because of this flexibility.
USB-C defines various “Alternate Modes” of operation. These modes allow some of the physical wires inside the USB-C cable to be used for direct transmission of data according to various alternate protocols, including DisplayPort 1.4, mobile High Definition Link mode, Thunderbolt alternate mode, and HDMI alternate mode. The other major reason for this push is that it can help make VR accessible to a larger set of machines or laptops with fewer ports — though as a matter of practicality, it’s going to be a while before consumer laptops without discrete GPUs are going to be driving VR experiences.
The new VirtualLink standard is claimed to deliver four high-speed HBR3 DisplayPort lanes that are scalable for future needs, a USB 3.1 data channel for higher-resolution cameras and sensors, and up to 27 watts of power.
There’s an interesting issue here that I haven’t seen called out or discussed anywhere. When DisplayPort is implemented over USB-C, it can be implemented with different amounts of available bandwidth. Offering four high-speed HBR3 lanes via USB-C means USB3 performance wouldn’t normally be available. This point is made in a slide from the USB-IF developer forum from back in 2016, shown above.
But VirtualLink says quite clearly that USB 3.1 performance is available. The formal website even clarifies that this is USB 3.1 Gen 2, which means 10Gbps of bandwidth. The most logical conclusion is that VirtualLink has been designed for VR, specifically, and includes additional bandwidth to further that purpose. But this also raises the likelihood that VirtualLink VR cables, despite being USB-C compliant, will also be specific and particular to VirtualLink-compatible devices.
There’s no word on when we might see supporting hardware, but at a guess it could happen with the next round of refreshes from companies like Oculus and HTC. Both firms are on-board, along with companies like AMD and Nvidia. The overall amount of vendor buy-in seems solid — and that’s always important with efforts like this.
Top image credit: VirtualLink