[PD] Re: [PD-dev] Pd on OS X

[chris clepper]

>Looking at your last (private) message:
>>The audio
>>doesn't stall per se, it's more like values aren't
>>getting updated consistantly so say a pitch sweep will
>>"jump" along with the numerical input.
>
>... it's sounding more and more like the real-time issue that Miller
>pointed out. A pitch sweep shouldn't be interrupted like that, in my
>experience, unless you have some other processor-greedy apps running at
>the same time.

renice -20 helps some, but even with the most basic patch and no 
other processes running it will still drop samples.  the gui 
shouldn't affect the audio at all with this setting.  also moving or 
changing gui elements in apps other than pd/wish will cause the 
dropout clicks as well.  looking at pd in the debugger, it looks like 
audio runs in it's own thread.  is this correct?

>However, the performance of Aqua Tcl/Tk doesn't help things, either.
>Controls like number boxes cause a bunch of screen-redraw interrupts that
>are themselves greedy. Part of it is apparently AquaTk canvasses still
>use QuickDraw.

quickdraw should be ok as long as they don't pile on the CopyBits 
which has become dog slow in OSX due to the double buffering.  i 
wonder how many buffers each graphic object has using the wish shell? 
one for tcl/wish + 2 for quartz?

>Still, the stated specs on your machine should be able to run PD fairly
>well, as long as you minimize the screen updates on patches where you
>demand good audio performance.

pd runs quite well on the same machine (g3/400) running linux.  since 
core-audio is well integrated into the OSX kernel, i would expect the 
performance to be on par or better than linux.  in fact i'm getting 
very low latency (<8ms) and good performance in other OSX audio apps 
on the same box.  can others contribute pd performance info on other 
macs?  pd runs fine on a dual 1ghz box, but what about older boxes?

>I think there's a lot still to be optimized in the MacOSX port, though,
>both in user experience and in performance. Chris Clepper wrote recently
>about compiling with different optimization settings. Might be worth a
>bit of experimentation...

the -03 compiler setting gave slightly better performance but nothing 
truly remarkable.  if i recall one of the main differences between 
gcc -02 and -03 was the unrolling of loops??

cgc




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