Tech Focus: Next-Gen Cloud vs. Console

The current methodology we've seen with OnLive in making games playable over the Cloud is pretty straightforward: even without factoring in the internet, all games have their own internal latency - the so-called input lag. This varies from title to title, depending on how they are programmed, but to give a couple of examples, we've measured Modern Warfare 3 (60FPS) on Xbox 360 as having a 50ms latency from button press to resulting on-screen action, whereas Battlefield 3 (30FPS) on the same console seems to be in the region of 116ms.

"In the here and now, we are being asked to take the hit in fidelity and response in favour of a more convenient experience. Going forward, can we have our cake and eat it? In theory it's possible."

The theory is that by running a console 30FPS game at twice the frame-rate - OnLive targets 720p60, remember - input latency is significantly reduced. For the sake of argument, let's say that 50ms is shaved off the response time. That's enough time to encode a frame, decode it and also take a bite into the transmission time over the internet. That's the theory, so how does it stand up in practise? This is very easy to test: measure OnLive latency, and compare it with the PC and Xbox 360 versions. The PC metric gives us the base latency of the game itself (the same code is used with OnLive remember), while the Xbox 360 figure represents the target latency in providing a console-like response.

The tests were carried out on a 50mbps Virgin fibre optic connection with no other traffic running on the line at the time, and we chose areas where the game was operating at its highest frame-rate - in short, as close to best-case conditions as we could manage. On other connections we were quite alarmed at how variable this measurement could be, and we were also quite startled at the variance caused by drops in game performance, server-side. Inconsistency appears to exaggerate the impact of lag.

Regardless, in these tests, the difference between PC and OnLive is in the region of 83 to 116ms, but the gap closes when compared to the console versions. In our experience, it's usually playable but it's noticeably laggy - to varying degrees. We've also noticed on a number of tests that there's something of a latency threshold around the 150ms level - if you're below that, typically control isn't flagged as an issue but if you're above it, people do complain. Bulletstorm on console comes in at around 133ms and there are few complaints about its response level. Compare and contrast with Killzone 2 at 150ms, which turned into something of a major issue (though perhaps because frame-rate drops did have a further impact on response).

At its best, OnLive dances around the threshold - noticeable but not an enormous issue. At its worst, it's well over it and unsatisfactory. Improving this is the key challenge. For a start, lowering latency as much as possible within the game itself will claw back precious milliseconds - something we've discussed already in our Optimising for the Cloud article we ran a while back. Perhaps if Cloud gaming gains traction, this will become more of a focus during development.

Similarly, ensuring a solid 60FPS will help, meaning that Cloud providers will actually have to deliver in that regard: OnLive proves to be rather variable in that regard and the more drops from 60FPS there are, the higher the latency. In essence then, developers need to be more mindful of the target platform, or else the platform itself needs more powerful hardware.

Secondly, the deployment of more datacentres closer to the client is an obvious move. David Perry has been talking a lot recently about ultra-low latencies between his various locations and Gaikai datacentres - specifically 8ms between his home and what we'll assume is the Californian server, and even as low as 5ms between his London hotel and the local Gaikai facility. Right now, OnLive UK is actually serviced by a facility in Luxembourg. Typically the further afield the datacentre, the higher the latency and the more opportunity there is for packet loss, so being more local has obvious advantages. Player-side, as infrastructure is upgraded more towards fibre, latency should also decrease there too.

But can any more be done? Gaikai's association with LG in getting their service available via Smart TVs may present further opportunities. Connect up an Xbox 360 to an HDTV and even in "Game" mode - which disables a lot of the set's lag-inducing post-processing - you can still be looking at latencies of 50ms just from beaming a digital signal from the console and getting it displayed on the screen. Even when measuring latencies on fast gaming PC monitors - with an advertised 8ms lag - the actual end-to-end measurements we're getting can be up to 33ms. Bearing in mind how much the Cloud services can achieve in the same time period, this is a remarkably inefficient and obviously another vector of attack that Gaikai could use in bridging the gap between console and cloud latency levels. If you're already integrated into the TV itself, why not try to make the most of it?

I would suggest that the kind of experience console users enjoy now with Modern Warfare 3 - in all its 60FPS, ultra-low latency glory - simply cannot be achieved with a cloud gaming service. But an additional 50-83ms gives us the same kind of response that we get from console FPS titles like Borderlands, Battlefield 3, Killzone 3 and Bulletstorm: all eminently playable, and none of which have been criticised for being too laggy. At the moment it's theory, but relentless march of technological innovation has a habit of turning this into palpable fact sooner rather than later.

It's almost three years now since I wrote why OnLive can't possibly work, and it's interesting to look back and see the points being made that were eventually born out (latency, picture quality) in subsequent analysis, but how fundamentally, despite the very significant, quantifiable drawbacks, it is actually playable.

In the here and now, we are being asked to take the hit in fidelity and response in favour of a more convenient experience. Going forward, can we both have our cake and eat it with a service that captures the essence of the modern day console experience, and perhaps even exceeds it by using more powerful PC hardware, server-side? With next-gen consoles the best part of two or even three years ahead of us, it'll be interesting to see if the Cloud-based engineering breakthroughs and infrastructure improvements can arrive before new local hardware gains the kind of critical mass Xbox 360 and PS3 enjoy now.