Re: Running two instances of my AU causes audio glitches in Logic Pro
Re: Running two instances of my AU causes audio glitches in Logic Pro
- Subject: Re: Running two instances of my AU causes audio glitches in Logic Pro
- From: Oli Donald <email@hidden>
- Date: Mon, 20 Sep 2004 01:39:28 +0100
Hi Urs,
Just me being stupid...I should have spent more time learning C++...i
wasn't aware that data declared outside the scope of your class
definition would be shared across all instances! Now I do, and it
explains my problem :)
Thanks,
Oli
On 19 Sep 2004, at 22:41, Urs Heckmann wrote:
Hiya Oli,
if the buzz is still there in a single instance when you *deselect*
the track, then it might be due to Logic's habit to use different
buffer sizes for selected and deselected tracks. Deselected tracks can
have quite odd buffer sizes, while selected tracks usually use 64,
128... 512 samples per render slice.
If it's not that... maybe you have some static data that is shared
across instances?
Cheers,
;) Urs
Am 19.09.2004 um 22:46 schrieb Oli Donald:
Hi,
My AU effect allocates 2 buffers of 1024 bytes, to do double
buffering. One is the output buffer, the other 'collects' audio until
it is full, then that buffer is processed and they switch places. The
single parameter dictates wether the processing stage multiplies the
buffer by 10.0 or 0.1. The idea is that the first instance multiplies
by 10, and the second multiplies by 0.1, so the output is the same
volume as before. This is purely to test that my double-buffering is
working.
A single instance set to multiply or divide by 10 works just as
expected. However, if I add a second instance, the volume of the
output audio is correct (ie 100 times as loud, same volume, or 0.01
times as loud) but it has a buzzing sound in the background. If I run
the two instances of seperate track's, Logic crashes after playing
for a brief moment.
Are there some things that need to be taken into account for an
AudioUnit to have more than a single instance running? I've read over
the code and can see nothing wrong, and like I said, they work fine
one at a time, but the bug seems to suggest that both instances are
sharing resources. Is this so?
Im running Logic 6.4.2, on OSX 10.3.5, and the plugin doesn't use
enough CPU to light up a single bar on the usage meter.
Cheers,
Oli
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