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DisplayPort Alt Mode 2.0 Spec Released: Defining Alt Mode for USB4
As the tech industry gears up for the launch of the new USB4 standard, a few more parts first need to fall into place. Along with the core specification itself, there is the matter of alternate modes, which add further functionality to USB Type-C host ports by allowing the data pins to be used to carry other types of signals. Keeping pace with the updates to USB4, some of the alt modes are being updated as well, and this process is starting with the granddaddy of them all: DisplayPort Alt Mode.
The very first USB-C alt mode, DisplayPort Alt Mode was introduced in 2014. By remapping the USB-C high speed data pins from USB data to DisplayPort data, it became possible to use a USB-C port as a DisplayPort video output, and in some cases even mix the two to get both USB 3.x signaling and DisplayPort signaling over the same cable. As a result of DisplayPort Alt Mode's release, the number of devices with video output has exploded, and in laptops especially, this has become the preferred mode for driving video outputs when a laptop doesn't include a dedicated HDMI port.
If you're willing to accept Display Stream Compression... New DisplayPort spec enables 16K video over USB-C
Previously: Forget USB 3.2: Thunderbolt 3 Will Become the Basis of USB 4
DisplayPort 2.0 Announced, Triples Bandwidth to ~77.4 Gbps for 8K Displays
Speed-Doubling USB4 is Ready -- Now We Just Have to Wait for Devices
(Score: 2) by Immerman on Saturday May 02 2020, @03:08AM
Hmm, you might be right. I hadn't actually run the numbers before, and I must admit I greatly overestimated the saccade speed - it seems that even with with very generous margins so that you're unlikely to ever focus outside the foveated render the benefits could be dramatic
Saccade speeds can exceed 500°/s: https://en.wikipedia.org/wiki/Saccade#Timing_and_kinematics [wikipedia.org]
So a very fast saccade and a rather nasty 20ms of lag could allow allow for a fovea displacement of 500°/s*.02s = 10° away from the "expected" position, or about 10% of the FOV of a current headset, or about 1% of the visible area.
Meanwhile the resolution of the fovea itself falls off to about 1/5th the peak resolution at 10° from the focal point (20° total) for a 30° foveated region (~10% of the total screen area) would capture just about everything you could possibly see at higher resolution within the next 20ms. And that's assuming just a single jump to up to 5x the background resolution. At a more comfortable 10ms lag, and with just a smidge of saccade-prediction, you could probably narrow the necessary fovea-rendered region dramatically.