USB HIDs are usually polled every 8ms to 10ms, which is plenty fast
(have you ever noticed the latency of your mouse pointer or
clicks?). I have not seen any reports of latency caused by [hid],
but I suppose it could be possible.
.hc
On Oct 7, 2007, at 8:30 PM, Warrior Bob wrote:
Hi list,
First off, I'm new to pd but it seems to be a fantastic environment. Big thanks to everyone who's worked on it.
I've run into a problem. I built a pd patch to translate joystick button inputs into MIDI note signals using hid and noteout. Indeed it functions correctly, and there are no logic errors that I can find as far as which button triggers which note. However there is noticeable latency, too much to use to play an instrument in realtime.
Using a MIDI keyboard to send the same notes (bypassing pd), I encounter no latency that I am able to discern easily. I believe the latency must be related to pd, either in my patch or in the hid object, or in my joystick's USB interface (a playstation to USB converter). Is this a known issue in pd or hid, or has anyone encountered this before?
If it helps, I am running on a G4 Macintosh, using pd .38.4 extended, and using the IAC Driver to get MIDI data between programs. I have hid polling at 1ms intervals, and am using the Ableton Live demo as my destination (triggering the Impulse plugin).
I am almost totally convinced that the latency is in the USB interface, and therefore there is nothing I can do, but I figured it was worth asking. I spent a while going through the list archives, Google, and the documentation but did not find anything.
Thanks in advance!
Dave H.
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