[PD] logical timing question

Claude Heiland-Allen claudiusmaximus at goto10.org
Sun Jan 11 17:27:00 CET 2009


Peter Plessas wrote:
> Thanks for the discussion Roman,
> 
> see below
> 
> Roman Haefeli wrote:
>> while not being 100% sure, what frank meant with the other timing
>> domain, i guess, he meant all the messages, that are not initiated by
>> [metro]/[delay]/[pipe] and co. this would be messages from:
>>
>> - the guis and clicks on message boxes
>> - networking objects [netreceive]/[tcpreceive] etc.
>> - [hid] / [comport] / [arduino] / [wiimote]
>> - [cltin] / [notein] / [midiin] etc.
>> - probably more
>>
>> all those messages lack the extra timing information and thus are
>> executed only at block boundaries. 

That's the adc~/dac~ block boundaries, so...
> 
> I managed to find something that contradicts here:
> A Gui-bang to a [t b b] to a [timer] in a subpatch with a [block~ 8192] 

...that's why.

> object. Clicking the bang very fast with my mouse gives smaller than 
> blocksize message intervals:
> print: 127.71
> print: 116.1
> print: 116.1
> print: 127.71
> print: 116.1
> print: 127.71
> print: 104.49
> print: 92.8798
> print: 104.49
> print: 81.2698
> print: 104.49
> print: 116.1

note the quantisation!

127.7 ms = 88 blocks exactly
116.1 ms = 80 blocks exactly
104.5 ms = 72 blocks exactly
92.88 ms = 64 blocks exactly

at 44100Hz with 64 samples per block

so i'm guessing your audio driver has a block size of 512 samples (8 * 
64), which Pd fills with its 64 sample blocks quicker than you can click 
twice => massive jitter of "logical time" vs "real time".

> usw.
> 
> Hmmm, still searching. Thanks for all the good pointers!
> 
> regards, PP
> 
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