Comparing VR Streamers

For playing PC VR games on standalone type headsets - Quest and Pico devices - you require some kind of application to emulate a tethered headset on the PC side, and an application to emulate a standalone VR game on the headset side, and pass the video and inputs back and forth.

These applications are streamers, and there’s plenty available! I wanted to compare them in terms of usability and functionality!

I won’t be diving too hard into display quality here, as while I have done some rudimentary testing of this before, it requires a lot of taking screenshots, comparing bitrate settings, and latency is hard to measure, and I just really don’t feel like it right now! None of them are exceptionally bad, so I don’t find quality a big issue here. Frankly my network can easily handle the bandwidth necessary to make even H.264 look fantastic, and my GPU is more of a bottleneck. Equally, the biggest latency bottleneck for me is AMD’s GPU video encoder, which no streamer can do naught about.

I will be comparing Pico Connect, ALVR, and Steam Link, in the context of a Pico 4 Ultra headset.

Virtual Desktop is notably missing here. That is because it is $20, and I used my shot at a free trial of it about 6 months ago when I compared it to Pico Connect for myself when I first got the headset. It was better at some things and worse at others on the quality front than Connect, and the UX is kinda quite a bit worse. Certainly any quality difference, if positive, wasn’t enough to justify paying extra. It does also have display mirroring though!

This is interesting when you consider that, for Quest users, Virtual Desktop is usually considered an unwritten necessity for using it for PCVR, as Oculus AirLink is generally regarded as shit. Virtual Desktop is also a gigabyte for some reason?

Since it doesn’t fit anywhere else, I’ll also note that Virtual Desktop and Steam Link are the only two applications that offer relay servers to connect to your PC if it is not visible on your LAN. All I can say is that I strongly recommend you never try to play VR like this, even dropping from 250Mbps LAN to 90Mbps LAN made my experience choppy and my compression artefacts extremely visible. Playing over a remote relay server sounds horrifying, therefore I don’t consider this an important distinction.

I would also like to preemptively apologize for the audio in these recordings. I forgot to disable microphone in screen recordings, and well, the microphone is mounted quite close to where I am breathing. Like, to stay alive. Oops.

Pico Connect

Pico Connect is Pico’s first-party streaming application. It is currently what I use in the real world for playing games as I have not found any alternatives to be overall better.

It is relatively feature rich, offering multiple codecs, bitrate choice, options for DLSS-style upscaling on the headset side, options for frame buffering and interpolation on the headset-side, options about where your audio will go when streaming, and so on.

It also is uniquely well integrated into the Pico OS - if you sign into the headset and your PC with the same Pico account then whenever your Pico is on the same LAN as your PC and you start it up, your PC will just automagically appear in the dock as if you had previously minimized the streaming (though, its not, it only starts streaming when you click on it!).

Two complaints I have with Connect are that it requires administrator privileges, and that it won’t let me push HEVC any higher than 150Mbps.

Pico Connect works just fine in wired mode, which lets you push nice and high bandwidths without network latency (Tetris Effect, I’m looking at you).

It is unique among the applications I’m comparing here in mirroring the desktop within the Pico OS home as well as just streaming a full VR environment. This is already a huge UX point for it, and as such it is also the only streamer here to let you temporarily leave your VR environment with SteamVR still running, and go back later, as the other streamers don’t have anything else to show you!

Pico Connect loads as a SteamVR plugin and through that is able to show Pico hardware in the status window, show Pico controller models in VR, and the SteamVR dashboard bar has options to fine-tune controller and tracker position, and if you have motion trackers paired, an icon will appear that immediately launches calibration on the headset side.

Here is a video of me using Pico connect (note that in most cases I would not need to start connect manually, it would have already started on login):

I will also note that the button on the top right of the streaming window shows “Launch SteamVR” if SteamVR/Steam is not currently running, and “Back to SteamVR” if SteamVR is running but not being streamed, either due to leaving VR from the headset, or due to opening SteamVR from the PC and not the Launch SteamVR button.

Steam Link

Steam Link is Valve’s streaming solution for VR. As I understand it is in beta for Pico hardware but I was able to find an APK for it here.

The streamer side is built into Steam, and its built off the same infrastructure as non-VR Steam Link. Indeed, if you connect a game pad to your VR headset, you can play normal video games over Steam Link just as with your phone, if that’s your jam! I don’t see why it would be, but idk, I’m not you.

Steam Link has pretty nice UX overall, it feels very polished. It has a nice UI, and opening it and interacting with it will play a variety of sounds lifted from Steam Big Picture mode; it feels almost wrong to hear sounds straight from a Steam Machine on my Pico headset, but sure. When you select your machine and click connect, it will automatically start SteamVR on your PC, and drop you straight into it.

For display mirroring, it simply relies on the SteamVR built-in display view. This isn’t really a feature of Steam Link per se since this is available in literally any streamer that uses SteamVR, but it works I suppose.

I find Pico Connect to be slightly lower friction in terms of starting SteamVR as it starts on login and can launch Steam for me, whereas Steam Link needs Steam to be running - but that said, if you were using this primarily, you would probably have Steam open on login instead, so its a very moot point.

Again, Steam Link will show your hardware in the status page and as 3D models, by nature of the client knowing what headset its on and the ability to integrate into SteamVR closely.

Being closely integrated into Steam, you configure its settings within the SteamVR settings, as an extra tab. Also, the latency information is neatly added to the frametime graph on the SteamVR status window, instead of being a separate thing. Pico Connect has no graphs, but an option to show latency and other stats as a headset HUD, and ALVR has a wide array of graphs but only on the PC side inside the streamer window, so I like Steam Link’s approach of adding the most relevant stat - network latency - to the same frametime graph you’re already using. You can also open a more advanced stats and graphs page on your PC with toooooons of technical info.

You cannot drop out of VR mode back into the Pico OS home using Steam Link like you can with Pico Connect. When you exit SteamVR via its UI, it will just disappear, though I found weirdly this broke my Pico OS Home passthrough. Odd but easily fixed by going into and out of full passthrough (headset double tap). This smells of a beta bug though.

Steam Link offers foveated encoding - which is not that uncommon, ALVR has settings for it and I am pretty sure Virtual Desktop does some form of it, but these are mostly static implementations that make the edge of your vision lower bitrate. Steam Link will, on eyetracking enabled headsets, which includes the Quest Pro and Pico 4 Enterprise/Pro, use your eye position to decide where to focus encoding effort, which is really exciting!!! It also appears to use headset inertia to kind of approximate where you might be looking (humans tend to look into / ahead of head movements) if that data isn’t there.

Sadly their method of doing this (presumably to allow them to relocate where the high quality part is on the fly) means that, unlike the other streamers, screenshots and recordings show a very clear quality boundary. This is not noticeable in VR to my eyes, but I will drop my one surviving Virtual Desktop screenshot after the video below, with arrows pointing to a low quality part near the edge and a high quality part near the centre.

Again, a video of me using it:

And that VD screenshot:

ALVR

ALVR is an open source streaming application. It somehow feels very different to anything else I’ve used in this category, as it’s less of a streamlined product and more of a tunable tweakable scrappy tool.

It often seems to crash or break, especially in wired mode, which needs to be pre-selected in the ALVR app, you can’t just select it afterwards in the client.

It has a looooooot of sliders and switches in the desktop side app, that lets you fuck with a bunch of stuff, including codec (including enabling codecs that will require software rendering!), bitrate, encoder settings, foveated encoding radius tweaks, forcing on HDR and 10bit even if the client doesn’t claim to support it (this usually results in Interestingly Wrong Colours), et cetera.

It requires VB-Cable to be installed to redirect your microphone while streaming, which is kind of annoying when Pico Connect just works on this front, and works very seamlessly indeed. I can be in a Discord call, put on my headset and pull up my desktop streaming, and suddenly the call just jumps to the headset including my microphone, then I close streaming and take off my headset and it just pops back to the right place. ALVR is less seamless.

Equally, when you open it, you get a passthrough limbo environment, which does nothing until the server (yes, really) notices a client it recognises and tries to start the stream. Then you get some basic status info and are dropped into SteamVR.

Unlike Pico Connect or Steam Link, SteamVR seems entirely unaware of what hardware you are using. You will see 3D models of Quest 2 controllers, the SteamVR Status window shows a Quest 2 headset, and the Steam Input configuration page thinks you have Quest 2 controllers too. You also get no in-SteamVR configuration.

Something that I think might be a side effect of the Quest-2-ification of the headset is that the lasers in the SteamVR UI feel like they come out of the controllers at a really uncomfy feeling angle. I know that this varies based on application, as every UI seems to reinvent its own VR interface - Pico OS, SteamVR, VRChat, Firefox Reality, OVR Toolkit, et cetera all have their own laser angles and renderings, their own keyboards, and their own bindings (for example, Pico Connect desktop mirroring maps A to left click and B to right click, whereas SteamVR mirroring maps A to right click, and OVRTK maps A to left click and long-holding A to right click). But even though it does vary per application, this particular case just feels bad and it only occurs with ALVR.

I do find it to be quite unstable, but once its working, I can generally comfortably play a session on it. I just wish it was less unreliable and janky.

When you exit SteamVR you don’t get dropped back to Pico OS, but rather back into the passthrough limbo, which seems odd to me, but does kind of act as a blessing when the stream (and often SteamVR entirely) crashes, which it will, since this causes the streamer to then see the client again and automatically kick SteamVR up the butt to auto restart.

It is also notable for being the main way to use a Quest or Pico with Linux SteamVR, but honestly using SteamVR on Linux is a weird proposition when WiVRn exists, as Linux SteamVR is really buggy, and WiVRn is much stabler. Also Steam Link probably works for this now anyway.

Here’s a video of me using ALVR. Note the crash. Lol. I tested like 5 times before this for playing with 10bit encoding and this happened like this every time. I have previously had sessions where it just worked:tm:, and sessions where I couldn’t get it to go.

Corollary: banding, colours, and breaking shit

So, I was hanging out in a minimal VRChat world the other night, with a gradiented skybox, and noticed banding in the sky.

I wanted to try out which streamer might reduce the banding the most, and tried all three of these.

My conclusion was in fact that none of them did - despite a testimonial from a friend using Steam Link on his Pico 4 Enterprise that “it noticeably fixes the banding”.

I took screenshots in all three with the same 250Mbps bitrate and as you can see, they all band. Interestingly I did notice minor variations in the colours of the final image:

Pico Connect seems to have slightly more vibrant colours - not that I’ve ever noticed a difference switching between it and anything else without side-by-siding them. ALVR is a touch darker than Steam Link but barely. Notice all 3 band about the same amount, though Pico Connect’s brighter colours do make the banding slightly more visible, I suppose.

As a fix, I wanted to try enabling 10 bit colours or perhaps HDR in ALVR, but flipping these switches did nothing. Switching on the option to force using 10bit even if the client doesn’t tell the server it can accept it gave me the following… spicy!:

Forcing HDR on with 10 bit gives the following:

and HDR with 8 bit as so:

Conclusion

I’m just gonna keep using Pico Connect. The display mirroring is worth it, and the OS integration is really nice.

Steam Link is worth keeping an eye on though, especially if you have eyetracking. I might revisit it when I build an EyetrackVR, but I suspect it only really works with headset-side eyetracking, so feeding in ET data on the PC side might not work. Who knows.

Sorry Virtual Desktop isn’t here I guess. I talked about it a bit from memory at least!

Hopefully some of you found this interesting, and I hope to see ya around here again later!

— Hazel