[linux-audio-dev] Re: OSC vs MIDI

[David Olofson]

On Thursday 02 September 2004 17.06, smoerk wrote:
> > OSC over bluetooth is interesting. Any comments on it? How easy
> > is the hardware to build? I know you can wire PICs to USB easily,
> > but I dont know much about bluetooth.
> >
> > Would it be worth adding a bluetooth transport to liblo?
>
> i never was able to get below a latency nelow 15-20 ms and spikes
> here and there (if you want run jitter-free i guess you have a
> latency of 30-50ms or more). i don't know if this is only my setup
> or if this is normal with bluetooth. for real-time musical
> controlers it's way to slow. but i guess there are still enough
> applications were latency doesn't matter.

I've noticed a lot of complaining about bluetooth wireless mice not 
being seriously usable for FPS games and the like.

Logitech has a wireless optical mouse that comes in two models; the 
"FastRF" MX700, and the bluetooth MX900. People who have used both 
say that the MX700 performs a lot better than the MX900, and people 
have returned MX900s after discovering that the performance is 
unacceptable for gaming. The mice identical, except for the wireless 
protocol, though marketting (obviously) suggests that the (much more 
expensive) bluetooth solution is plain better, with no side effects. 
Some customer asked Logitech about this, and Logitech replied that 
bluetooth has much lower bandwidth than their FastRF system...

I *think* bluetooth should be able to handle the bandwith requirements 
of a mouse (125 Hz frame rate for the MX models, IIRC), but 15-20 ms 
latency spikes would be an issue that cannot be fully compensated for 
regardless of bandwidth. Jitter or delay (buffering to eliminate 
jitter) would cause problems with real time controllers, such as mice 
or musical controllers.


//David Olofson - Programmer, Composer, Open Source Advocate

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