[PD] Key-related audio glitch, OS X Intel
Hans-Christoph Steiner
hans at eds.org
Mon Jul 10 00:31:32 CEST 2006
On Jul 9, 2006, at 6:14 PM, Phil Stone wrote:
> More information on this:
>
>> I've been playing with Miller's experimental version for Intel OS
>> X (see http://crca.ucsd.edu/~msp/Software/pd-imac-test.mac.tar.gz )
>> and for the most part, it works great.
>>
>
> [...]
>
>> Typing on the computer keyboard (e.g. to enter something in a
>> number box) after focus has just transferred to PD, makes a crunch
>> or pop in the sound right at the moment of the first key press.
>> Subsequent key presses do not interfere with the sound, until
>> focus is switched to another app (or maybe even another PD window
>> -- I can't reproduce this very consistently) and then is returned
>> to PD.
>
> More exacting testing shows that the glitch can be consistently
> reproduced using the simplest audio patch, [osc~ 400] - [dac~]
> or even the Media Menu -> Test audio app.
>
> Window focus has nothing to do with it: it is related to time. If
> a key on the computer keyboard hasn't been pressed for n seconds (n
> equals about 10 on my system), the next key press causes a
> significant audio glitch. Further key presses, if made within n
> seconds, don't cause a glitch. *After any pause of n seconds or
> more, the next key press causes the glitch.* Also, there need not
> be any key-input controls on the PD screen; as I said, the simplest
> audio patch can reproduce this.
>
>> I've tried different latency settings and this has had no effect.
>>
>
> The -rt startup flag makes no difference. Completely disabling
> Dashboard, and effectively disabling Spotlight, makes no difference.
>
>> This seems like some bad interaction between the OS key-handling
>> and PD.
>>
> I would really appreciate it if:
> a) someone on PPC OS X could see whether this happens to them.
> b) someone else running the experimental Intel version of PD
> (anyone?) could try to replicate this.
>
> Also, I'd appreciate some noob-advice on whether I should I file a
> bug report on this.
I tried this using Pd-0.39.2-extended-test4 on a G5 using the "Test
Audio and MIDI" patch. I could not make it click with realtime mode
on or off with the standard delay of 50ms. I switched it down to
13ms with realtime turned off and got some clicks when switching
focus. With realtime on, I got no clicks at 13ms. It sounds to me
that you need to bump up the delay a bit perhaps. I forgot to
mention, I am using portaudio, not jack.
.hc
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