Oculus App v23 beta (bandwidth testing)

[clouds5]

clouds5 said:

So if i use 250-350Mbps I notice a big reduction in compression artifacts on my Link in fast games like Dirt Rally 2.0. Unfortunately when I use anything above 250mbps I also get stutters in gameplay (fps is stable!). My Link is with a generic USB 3 cable (USB test measures 1.2Gbps). Should be more than enough bandwidth for 350mbps I think? What could be the issue?

-->Just copying this from the Rift/Rift S forum, because it mainly concenr

After further testing and a different setup (add-in PCIe USB 3 card) I get 1.8Gbps in USB test. USB bandwidth isn't the issue as I suspected. When you set the Performance HUD in debug tool to "Oculus Link" in the upper left corner you get a encode/xfer/decode graph (blue, green red: what color is what?). I found out that when I set the encode bitrate too high (250+) I get frequent spikes above ~10ms in the blue line (I'm assuming that's encode) and that results in stutter/lost frames that don't show up in other performance graphs. FPS is rocksteady at 72fps and it's not dependant on render performance (tests done with Dirt Rally 2.0 VR on a RTX 2070, 16GB RAM, i7-6700) but the selected bandwidth.

You can actually test it in Oculus Home, just open the Link performance HUD and change the bandwidth in debug tool (needs oculus app v23) it changes in realtime - no restarts required. The 3 graph lines stay very close together up until about 150mbps, then above ~250mbps the latency increases from ~5ms to ~8ms on green and blue, which isn't really an issue, but also, spikes to ~12-16ms are introduced which are very noticable. Especially in fast games like racing (every time notice a stutter, I look up to the HUD and see a spike in the blue line...).

Would be interesting to see if you guys have the same results? Maybe it's just a problem with my setup...? Anyway I'll stick to low bandwidth for now, even though ~300mbps+ looks soooo much better with Dirt Rally 2  

[rtathegawd84]

I've heard RTX 2060's can do 500mbps bandwidth with no problem from two people so it's not likely the gpu, definitely 350mb compression should be no problem!!. Do you use virtuallink? (on the back of the 2070) as I get 1.8 gbps speed on my mobo type C and I get 2.5gbps on the virtuallink port on mt rtx 2080. I'm not so sure on the latency as I haven't looked at it but I've not had problems using 500mb or noticed the latency when moving up above the stock 150, maybe it's so small I haven't noticed!?!

[clouds5]

hmm it's definately noticable. Sadly, my 2070 doesn't have a USB C port. I use a USB A 3.1 port from a PCIe usb card (It's the same when I use the mainboard port). I have a USB C port but only the short cable that came with the Quest2, I will test that. But I don't think it's a bandwidth issue? Even USB 2.0 can do 150mbps without any issues... So my USB 3.1 1.8Gbps should do ~300mbps easily.
What I feel really isn't more latency though, it's stutters like dropped frames, even though the framerate is stable. The problem seems to be with the encode/transfer/decode process. Could also be that it's just Dirt Rally 2 that has these kinds of issues.