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View Full Version : Do more wiimotes attached to a computer increase latency?



ianhattwick
10-01-2010, 12:33 AM
I know that adding a motionplus extension and nunchuk decrease how fast the wiimote data is updated - I'm just curious whether this applies to adding more wiimotes?

camille
10-01-2010, 09:15 AM
Hi Ian,


Here's how it works:

- attaching a MotionPlus to a Wiimote only doesn't decrease the rate of data being sent from the Wiimote to the computer.

- attaching a Nunchuk to a MotionPlus will divide by two the rate of informations sent by the MotionPlus but the Wiimote's sensors are unaffected. (accelerometers, buttons, IR, etc.). The reason is directly connected to the format of the data that the Wiimote sends to the computer.


In the case of the number of Wiimotes being connected to a computer, the factors are different: It depends of the computer's radio model, and the ability of its driver to process data quickly. For example, on my computer you can only connect 4 Wiimotes, whereas on the newest MacBook Pros, you can use up to 7 Wiimotes without a problem.


Another thing to consider, since Bluetooth is a protocol that "shares" radiowaves between devices, is the amount of radio activity in the range of 2.4 GHz. If there is a lot of WiFi hosts, bluetooth receivers, etc., the connection will be indeed impacted. I cannot say however if this impact translates in the form of latency, I'd rather say some kind of jitter.


So I guess, that yes, connecting several Wiimotes will have an impact on the reliability, latency and jitter of the connection, but not in the same way as connecting a Nunchuk to a MotionPlus.


Best,

Cam

Ida
10-17-2010, 01:21 AM
Hi! I have a related problem and thought to write it here instead of opening a new thread -
Was using OSCulator perfectly with 1 wii, sending OSC messages to pure data
Today I tried to connect another wii. I guess I did it correctly.. (the same port as the other and just the routes are different by the wii/2/...)
It works, I get signals.
BUT, Suddenly the signals are very latent and non-responsive. I see it already in the OSCulator Quick Look.
When I re-connect them, sometimes it worked perfectly, sometimes there is only 1 responsive and 1 extremely latent and sometimes both are latent.
My computer is a quite new macbook pro (~1 year old) So I guess it is not the problem. In my room I have an internet router and... I dont think that any more bluetooth devices

What do you think is the problem?...

Thank you so much!
Ida

Ida
10-17-2010, 01:25 AM
If I may add - yes, it sometimes look like a kind of a jitter, but really annoying. I have no possibility to work with this.
I wish this could be solved cuz before it was really amazingly responsive and accurate....

thanxxxxx

camille
10-17-2010, 11:43 PM
Hey Ida,

This is interesting, I had a similar email from a user using Pd.
Here was my answer:


Once the Wiimote is connected you should be able to run it with no problems. I have not heard of a degrading performance over time. However there are several factors that could affect the speed of packets sending.


When you have only a few packets every second, is the Wiimote standing still or are you shaking it? Osculator filters the data in a way that only changed values are sent, but you should still get a fair amount of packets coming to Pd, so I'm not sure that this is a real issue.


In order to be sure that the Wiimote is working well, you could open a Quick Look window on the messages you are sending to Pd to check that the graphs are updating like they should.


If you are sending Wiimote data from one computer to another it could be possible that you have some network issues, but then again I don't think this is the case here.


OSCulator uses a kernel extension to prevent the OS from seizing the Wiimote during the connection process. In order to do that it needs to know the Wiimote address, so it has a small database of every known Wiimote address space. There is again a possibility that your Wiimote is not yet known to this database. Would you mind telling me your Wiimote's address so I can check? You can find it in the Wiimote Drawer, where you have the list of connected Wiimotes.


As a last note, you could perhaps check that Pd is not overloading. Chances are that your Pd patch gets saturated and doesn't have the time to poll data from the networking fast enough in comparison to the audio process it is running. Instead of using OSC as an input to Pd, you could try MIDI for a moment to see if you experience the same problems.


I hope it helps. I am not an expert in Pd, so I can only give you pointers. Let me know if you find anything.

Ida
10-18-2010, 12:03 AM
thanx Cam.
I just want to say again - the problem appears already in the Quick Look in OSCulator... (The green curves)
Already there I observe a huge latency... sometimes a second or so.. and sometimes its changing
So I guess it happens before its sent to PD and unrelated to PD, no? I thought its related to the bluetooth connection
I will try MIDI too.
If it can tell you something, the 2 wii addresses that I am using are-
00-17-ab-39-f9-28
00-17-ab-39-5-59

I will try more possibilities and will let you know if I find something
Thank you,
I.

camille
10-18-2010, 03:24 PM
Hey Ida,

This is weird that I received the same week two identical reports about using Pd and Osculator.
I'm sure there's something wrong but really can't tell what's happening, I have too few clues.

It would be great if you could send me the oscd and pd files so I can reproduce the problem here.
Please send them by email, and give me the version of Pd, OS X and OSCulator you are using.

Best,
Cam

Ida
10-19-2010, 11:19 PM
Hi Cam!
Now it works good... I simplified a bit my patch in PD and it seems to work ok now...
A few days ago it also went good and suddenly not again...!
Well, I hope it keeps going well.. and will keep you informed.
If you want I can anyway send you the PD and oscd files... do you want?

Thanks for everything until now,
cheers,
I.

camille
10-20-2010, 12:14 AM
Thanks for letting me know.
I'll be happy to give it a try.