Bold claims have been made for PlayStation Move in terms of its latency, or so-called controller lag. At both the GDC press and developer events, Sony itself pegged the lag of the new motion controller at "under one frame".
Previous information from the guys who created the PC drivers for the PlayStation Eye camera also indicated that the mechanism is extremely low latency. In that case, a lag of one frame was measured, and the chances are that in this case it was probably impossible to measure if it was actually any faster.
At the nuts and bolts level, then, it's difficult to argue with the case being put forward when both official and independent sources corroborate each other so closely. In use, however, on actual PlayStation Move software, it's clear that there is some level of latency.
Regular readers of Digital Foundry will know that lag is basically inevitable. The creation and flipping of a framebuffer within the console causes lag, and in measurements (not just ours), the very fastest response has come from the PS3 XMB, which has been pegged at three frames, or 50ms.
On top of that, of course, the proliferation of flatscreen panels means that we have display equipment where latency can change radically even between screens made by the same manufacturer. Anything from two to five frames' additional delay (33ms to 84ms) is fairly common.
Muddying the waters still further is that the PlayStation Move is such a precise implement that game-makers may feel the need to smooth the input, reducing natural player jitter, but again introducing further latency.
So, with all that in mind, I set out to get some idea of the lag in Sony's motion controller while at GDC. The chance to get hands-on with Sony's augmented reality demo (used by the firm itself in demonstrating the controller's tech credentials) was probably the best possible test, and presumably the screens Sony used would be the very fastest consumer-level panels it has bearing in mind just how much "precision" was mentioned at both of the company's GDC events.
A cheap and cheerful Kodak Zi6 handycam was used to film the proceedings. It's an unremarkable camera, but it can film at 60 frames per second, making it very useful for measurements like this where temporal resolution is far more important than the number of pixels.
The augmented reality demo is a worthwhile test for a number of reasons. Firstly, actual game-level processing is at a minimum. The demo is simply displaying the camera feed (in itself used for some of the motion control calculations), and overlaying a couple of fairly simply 3D shapes. Make no mistake, this isn't some Killzone 2 level workout of the PS3 hardware.
While exact latency measurements aren't possible in these conditions, a ballpark idea of the level of response isn't a problem at all. The methodology is remarkably straightforward. Keep your hand as steady as possible, then make fast motions with the controller. Count the frames between your hand moving, and the motion being carried out on-screen.
Equally illuminating is to stop your movement suddenly, then count the frames necessary for your on-screen counterpart to catch up. While not 100 per cent accurate, repeat the process enough times and the frame difference becomes fairly evident.
Bearing all of that in mind, and recognising that we don't know how much latency the display itself is adding, I'd say that a ballpark figure of around 133ms of controller lag (give or take a frame) seems reasonable, certainly not the ultra-fast crispness of response we see from games like Burnout Paradise or Modern Warfare, but fine for most of the applications you would want from such a controller.
Also worth remembering is that the motion control itself is only a part of the mechanics within the Move. Much of the internal mechanics, along with the button presses, will all be sent to the PS3 via the Bluetooth connection: lightning-fast and perfectly equivalent to the response levels of the DualShock 3. In terms of a more definitive test, a 60FPS game with comprehensive support for both Move and the traditional controller could be interesting
http://www.eurogamer.net/articles/playstation-move-controller-lag-analysis-blog-entry
