IMR is one of several companies creating technology to enable a future where high-end VR headsets can break free of the tether that keeps them connected to the host PC. The company's secret sauce is their proprietary compression algorithm which they say is made-for-VR, allowing for huge compression at much faster speeds than traditional video compression technology. I recently got to check out the company's system first-hand during a visit to their Silicon Valley office. IMR's Approach to Wireless VR [caption id="attachment_62619" align="aligncenter" width="640"] IMR CEO Dr. Daniel Fitzgerald prepares the wireless system | Photo by Road to VR[/caption] Of the several companies today working on solutions for making high-end VR headsets wireless, there are a number of different approaches. Some companies are using newer ultra-high bandwidth 60GHz technology in order to pipe over the large quantities of data necessary for today's VR headsets operating at 90Hz and 2160x1200. Other companies are using existing video compression codecs to compress that data in order to fit it into the bandwidth of wireless technologies that are already out there. [irp posts="57452" name="6 Companies Aiming to Cut the Cord on High-end VR Headsets"] IMR's strategy is largely the latter, except instead of using an existing compression codec, they have developed a proprietary compression algorithm which they say is optimized for VR, whereas off-the-shelf codecs were designed for the compression of traditional digital video. Why is that important? One example the IMR likes to give is to point to a codec like h.264, which IMR says uses frame-to-frame compression (comparing one frame to the next) which necessitates a minimum 11ms latency given the 90Hz framerate. IMR claims their proprietary compression technology doesn't use frame-to-frame compression (or sub-pixel sampling) and can achieve 95% compression with encoding and decoding happening in 1ms. The entire end-to-end wireless VR system, including latencies introduced by various hardware interfaces like HDMI is around 2-3ms, the company says. Achieving 95% compression is a big deal, because, as IMR says, it opens to door to sending the data required for today's VR headsets over existing wireless technologies like 5GHz 802.11ac and others which can meet similar bandwidth. So those are the technical tidbits, but how does IMR's solution perform when put to the test with a VR headset? That's what I set to find out with a recent visit to the company's Silicon Valley office. Hands-on With IMR's Wireless VR Proof of Concept Module [caption id="attachment_62618" align="alignright" width="325"] Photo by Road to VR[/caption] At IMR's office I got to see a proof of concept system that demonstrated the company's core tech running with an HTC Vive (though the system can work the Rift and other headsets as well). At the office I found a little white 3D printed box sitting on a table connected to the Vive. On the side of the box you'll notice a comically short yellow cable that plugs the box... into itself. That cable actually connects the encoding and decoding hardware together, allowing the compression algorithm to be easily debugged without the need of a wireless link. To show the systems wireless performance, IMR removes the yellow cable and instead plugs in a wireless transmitter to one end and a receiver to the other, transmitting the same data wirelessly that would have otherwise gone over the short yellow cable. So what you'll see in the photos is what appears to be a wired HTC Vive, but the data is actually being transmitted wirelessly, just in a way that looks a little different but makes sense for a prototype (and is still capable of demonstrating the principle functionality of the system). [Most of the photos in this article show the yellow cable still plugged in, but this was only during an A/B test to compare the latency between wired and wireless.] The end-goal of the system is of course is to have one half of what's in that white box attached directly to the computer and the other half on the headset itself (rather than sitting in the same enclosure), and that's in development. [caption id="attachment_62620" align="aligncenter" width="640"] Photo by Road to VR[/caption] With the system running wirelessly, I played a range of familiar games including theBlu, Space Pirate Simulator, and Job Simulator, and as far as latency is concerned, I couldn't perceive any difference between what I'm used to with a wired HTC Vive. Wired or unwired, I wouldn't put any money on my ability to guess which was which. [irp] When it comes to visual quality, IMR says the decompressed image is "indiscernible from the original." I'll agree that the image quality is very good (especially for the claimed 95% compression), but strictly speaking, not indiscernible. I would be confident in my ability to guess better than chance if I had to do a blind test comparing the original to the decompressed image through the headset; that said, the quality IMR is achieving is easily good enough to make this a viable solution worthy of consideration if you want a wireless VR experience. My feeling is that general users not specifically looking for compression would probably not realize a difference in real world usage. Continue Reading on Page 2 >> Tuning Challenges IMR says their algorithm is highly tunable. Depending upon the bandwidth of the wireless technology employed, they could dial the compression back to, say, 75% instead of 95%, and at that point the difference in image quality may indeed be indiscernible even to the knowing eye. I saw evidence of this algorithm tuning in action from when I first got a look at IMR's compression tech back at CES 2017 earlier this year. Between then and now there was a marked increase in image fidelity, even at the same compression rate. The difference was so drastic that I went from feeling like the tradeoff between image quality and IMR's wireless tech was not worth it (at CES), to feeling like it was good enough (during this latest visit) to warrant very serious consideration of whether or not to cut the cord on the Vive. [caption id="attachment_62621" align="aligncenter" width="640"] Photo by Road to VR[/caption] Of course, as with any compression technology, some things compress better than others. There's still a few areas presenting challenges to IMR's compression. Chief among them are gradients and dark/low-contrast scenes. Both can cause some amount of banding and artifacts which wouldn't be seen otherwise. IMR says they have ways of dealing with those elements and are continuing to tweak their algorithm to compress different parts of the scene smartly to avoid artifacts. But you can imagine the challenge of getting the algorithm to behave correctly 100% of the time across lots of different VR content, each with its own optimal compression. To aid the algorithm in ensuring the right compression approach for the content, IMR says that it would be possible for games to send parameters to the algorithm for per-game adjustments which could potentially allow for fine-tuning to be done by developers or crowdsourced to users. Today & Tomorrow's Headsets [caption id="attachment_62626" align="aligncenter" width="640"] A concept rendering of what IMR's wireless VR add-on could look like | Photo courtesy IMR[/caption] The little white box I got to see was very much just a proof of concept. The next step for IMR is turn that box into a reference design that can actually be mounted on the head for truly wireless gameplay. The company is in the midst of creating the reference design and will soon demonstrate it publicly. At the outset it will look rather bulky, but IMR says that the system could be easily miniaturized and integrated directly into VR headsets of the future. IMR says that their compression tech can support current generation VR headsets like the Rift and Vive using existing wireless tech like 802.11ac. For future headsets pushing higher resolutions, the company is hoping for the proliferation of more cutting edge 802.11ad tech which has the bandwidth for up to 4k per eye. [irp] According to the company, the algorithm has also been architected to be ready for eye-tracking, a feature expected to come to VR headsets in the near future. With eye-tracking data piped into the algorithm, IMR says it can further optimize its compression for the areas where the eye is looking, while saving data elsewhere (similar to foveated rendering). - - — - - With the demonstration of their core technology, IMR says they are seeking a partner who would manufacture an add-on device that would allow the Vive and Rift to be adapted for wireless VR, and that could come to market in 2017. The company is also sharing their reference design hardware with partners who may want to integrate the technology directly into a VR headset.