To me it looked like a ton (two seconds or so) of latency, not pre-recorded video.

And I would expect latency for such heavy DSP work on a phone.

This is correct. The movements match up just fine, but the reaction time there is something above 2 seconds.

They need to buffer to get a Fourier transform and to do the autocorrelation.

They say they use an "inaudible high frequency soundwave", so that should be > 20kHz. Shouldn't a buffer of a few milliseconds be more than enough then?

Presumably the buffer is longer to make the system more robust by avoiding spurious detections, not because of some fundamental limit like the Nyquist rate. You would need to set the buffer size experimentally.

> I just don't think they really have anything usable.

I'm not sure that's the purpose. I wouldn't think of this as being intended to be a fully usable product right now. They could be intending it merely as an interesting experiment to explore new possibilities for interaction with mobile and wearable tech.

Another CS student came up with a virtual keyboard using the iPhone's accelerometer[1]. It only had ~80% accuracy[2], so was it all that useful or practical? Probably not. But could it lead to another person or company refining the technique for production in the future? Certainly.

[1] Video: https://vimeo.com/49780741

[2] http://www.gottabemobile.com/2012/11/13/cs-student-turns-iph...

I bet you have RSI within a week banging on a desk like that.

If it comes down to using something other than your fingers, someone has the nose working as a user input device:

http://www.looknohands.me

I would totally disagree. I don't think it would have to have much fidelity or low latency be insanely useful. The huge advantage is no extra hardware necessary. And maybe it might be hard for you to believe it could do what you want it to do but I'm guessing your vision is pretty narrow.

This reads like a personal attack.

If the tech is great then wonderful, but I still remember LeapMotion...

Have you tried the Orion SDK? It's an order of magnitude improvement in tracking accuracy, even with the older hardware. https://developer.leapmotion.com/orion

I tried the "massive improvement" they released before Orion and it was still terrible.

Only so many times a company can say they've got their issues ironed out before I stop believing them.

Orion really is quite impressive. I tried the improvement as well. Orion actually works.

Hmm, I'll have to try it out tonight. I have some 4-year-old v0.6 and v0.8 hardware in a drawer somewhere.

LeapMotion is not precise?