[PD] distorted sine on OSX 2.6.8 with firewire interface

[Roman Haefeli]

Hi Orm

On Thu, 2012-02-16 at 12:37 +0100, Orm Finnendahl wrote:
> Hi List,
> 
>  some of my students reported problems with pd using external firewire
> interfaces on MacBooks with OSX 2.6.8. A sine wave from the "test
> audio and midi" panel is very distorted.

What version of OS X is that? Do you mean 10.6.8?

> We encountered this problem on a consumer ESI Interface and on the RME
> Fireface. We tried different pd versions (0.43 and 0.42 branches,
> vanilla and extended) using coreaudio and jack with the same
> result. The internal sound card and standard usb interfaces sound fine
> with pd.
> 
> The problem seems strange as the firewire interfaces work without any
> problems with other audio applications like logic or live.
> 
> I tried to google this problem but couldn't find anything. Is this a
> known issue and can someone comment on this or give any advice how to
> proceed?

As an only occasional Mac user myself, it's probably just a shot in the
dark, but have you tried playing around with the sample rates of Pd and
your soundcard? Could it be that the sample rates are not synced for
some reason? Does the sound of the distortion change when changing the
sample rate?

For identifying the problem, it might be helpful to have a recording of
that distorted sound. Is it a clipping, is it regular interruptions in
the audio stream, does it sound irregular/noisy (broken byte-ordering)
etc.? Could you post a link to a recording of a distorted 440Hz sine
wave somewhere?

Roman