latency

[ryklin]

Hi All

I discovered a very significant latency when running my app on the Acer Aspire S7 w/Core I5. This is one of the fastest of the small and light laptops.

the eye tribe UI calibration works fine and the mouse pointer control is responsive. However, my own app has a terrible lag when running specifically on the aforementioned hardware. When running on any other computer, there is no lag. Don't know why. It's not the graphics card, I'm not using any hardware acceleration for rendering graphics.

[hendersond2004]

I'm coding in .net and find that drawing any image (bitmap ect) to the screen using graphics.DrawImage is very slow, especialy on image larger than 800x800
You need to look at DirectDraw hooks into the graphics card to draw things much quicker!

[ryklin]

Did I say i was using .Net? Did I ever reference graphics.DrawImage in my email? No I did not.

If you don't know what you're talking about, it's better to keep quite, because you'll end up leading people in the wrong direction and consequently burning precious time.

[melchimm]

Whoa, that response seemed a bit harsh!

I read hendersond's post as a suggestion to try using hardware acceleration. DirectDraw may or may not be the best method (I generally use OpenGL), but I don't think that his advice is limited to programmers using .Net. Regardless of what programming language you use, using hardware acceleration will almost always result in snappier graphics performance.

You may have a very good reason not to use hardware acceleration, but I suspect that for most users experiencing laggy graphics performance, hendersond's suggestion is actually useful.

[Martin]

Could stem from many factors, difficult to tell without more detail on your platform (e.g. OS, framework, language) and the purpose of your application. I can't really tell if this is related to EyeTribe software, the specific laptop or your own code.

What computations are you doing on the Gaze Data callback? This would be my first point of interest as it is frequently called.

[ryklin]

Sorry for the harsh response; I've been in this game too long and heard to much BS from people. In any case, I will figure this one out on my own.

I might add that my program also interfaces with the EyeX and other additional models, which all work without any latency on the same hardware I mentioned earlier. Therefore it's reasonable to surmise that the problem stems from the EyeTribe and not any other factor. While the suggestion to use hardware accelerated graphics is an excellent method of optimization (maybe not directdraw hooks per say), that has nothing to do with my program. I never even said my program has a complex graphical view, only that there is a latency on a specific machine, and not on others, and that the EyeTribe UI does not exhibit a latency. That's all the information I gave.

I'll report back when I have solved the problem.

[hendersond2004]

At risk of getting my head bittern off again,

There has been an update to the server code that and has some stuff about latency improvements in the change log, of course I'm assuming that you are using the server to interface with theeyetribe however I understand you have not posted that you are or are not, just a suggestion.

**runs away and cowers behind a desk**

[ryklin]

I don't believe it is possible to circumvent the server when interfacing with the eyetribe, so yes I do use it. I am looking forward to testing the new release of TheEyeTribeSDK-0.9.49-x86

Also, here is another latency update. It seems that jerking my head around is what causes the latency. If I hold my head relatively still, then both gaze and eye position is uniformly sampled. Once I started making sudden head movements, the latency emerges.