Re: [microsound] OS X woes

[ben nevile <bbn@xxxxxxxx>]

i have had a couple of requests for
clear instructions on how to verify the bug:

1. find a low frequency sound source that you can rely on.  a 
scientific grade waveform generator is the ideal test tone, but a low 
tone from a synth would be OK too.  the closer to a sine wave the 
better.

2. record 15 seconds of this noise into your favorite audio application 
with very little else happening.  no plugins running, etc.  save to 
disk (call this file A.)

3. get a bunch of other things happening on your computer so that the 
CPU will be occupied with a lot while it is recording.  eg, start a 
bunch of plugins.  get the CPU % above 70% and then record 15 seconds 
of the same noise under this increased load.  save (call this file B.)

4. set up a high-pass filter on a new track, maybe with the cutoff at 
10k.  the idea here is that we want to largely filter out the bass tone 
we just recorded.  apply this filter to audio file A and bounce to disk 
(call this C).  do the same for B (and call the file D).

5. have a look at C and D.  we've just recorded a low tone and high 
pass filtered it, so the signals ought to be very very small.  make 
sure the program you are using can zoom in a lot... most of the DAWs I 
know should be ok.  if you can't see anything but flat lines in your 
audio program, normalizing the files might help bring out the features 
we're looking for.  C should be relatively flat, and D should have 
spikes, or bursts.

if you get to stage 5 and can't see anything wrong with the second 
file, try adding more effects and repeat from step 3.  if you still 
can't see anything wrong with it email me and I'll have a look at your 
C and D files myself in matlab, where it's easy to scale the data in a 
nice plot.

Ben

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