Wagner James Au / New World Notes

Philip Rosedale has a classically Philip post announcing a new plan to attack lag in Second Life — by reducing jitter:

"Jitter" refers to the difference between when a frame is displayed and when it was expected to be displayed. For example, a game running at 60FPS is supposed to display a new frame every 16 milliseconds. But in reality it sometimes is late… once in while the computer might be busy and the next frame might appear 25 milliseconds after the one before it, meaning there is a ‘jitter’ of 9 milliseconds.

Even when the average framerate is high, jitter is very noticeable. This is because 3D environments present us with lifelike scenes in which there are moving objects. Your brain is incredibly good at predicting where moving objects are going, and when a frame shows up late, it means that moving objects appear in a different place from where you predicted them. This cause a jolt of ‘surprise’ in your brain, which is unpleasant and takes you out of immersion.

A cool web demo, come math and technical details follows, but the main takeaway is he and his team just created a new Second Life test viewer that tracks jitter:

If you download this project viewer (scroll to bottom for binaries), you can press Ctrl+Shift+S and look for “Normalized Period Jitter” and “normalized frametime variation” metrics just under jitter in the statistics window. Teleport around to different experiences and see which statistic you think is a better match for your experience, and feel free to share what number(s) you think are the edge between “Good” and “Bad” for you.

Go here on GitHub to get Second Life Test 7.2.0.16532322204 and try it out. The jitter statistics window looks like the screengrab above (courtesy Philip).

It's a very interesting approach to the problem, though I still think at least part of the problem should also be addressed through the UX — namely, add a Loading Progress Bar:

There's many variations, like a "Buffering" counter or a red line that slowly moves across your screen, but they all convey to the user the same basic idea: Your content is coming, but it's not optimally ready yet, so just be patient, dammit. On the Internet, the progress bar is such an ubiquitous visual cue, adding it to the Second Life experience should do quite a lot to make SL lag more bearable.

hen you want to stream a television show online, or play a Flash game, for instance, the lag time usually lasts several seconds to several minutes. But when you sit there waiting for the latest episode of "The Daily Show" to load up, or the latest Kongregate game to play, you rarely complain, or if you do, you're much more likely to blame your broadband provider, than the site with the content you're requesting.

You can tell how long ago I made this suggestion from the reference to Flash games!