[PD] Key-related audio glitch, OS X Intel

[Hans-Christoph Steiner]

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