[PD] hid object and latency

Warrior Bob mailinglists at thefighting.org
Mon Oct 8 02:30:58 CEST 2007

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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