Re: Audio Units and virtual memory
Re: Audio Units and virtual memory
- Subject: Re: Audio Units and virtual memory
- From: Bill Stewart <email@hidden>
- Date: Wed, 26 Feb 2003 15:02:04 -0800
On Wednesday, February 26, 2003, at 01:05 PM, Glenn Olander wrote:
Coming from OS9, one thing that I'm not used to dealing with is
virtual memory. When my plug loads and a note is played which uses
a wave table entry that hasn't been used before, I get a drop out.
There's an API that you should support:
MusicDevicePrepareInstrument
The value of this (if you're talking midi is)
0xMMLLPP
where MM is the 0-127 range of a MSB bank number
LL is the 0-127 range of a LSB
PP is the 0-127 range of a Patch Change message
These are packed into byte boundaries.
Your "host" should be calling prepare instrument before it expects a
glitch free patch change to occur. I've been doing some work on the
MusicSequence / Player to actually fix this properly (which it now is:)
I presume that's due to paging in the wave table? I so, I would
imagine the drop out could occur again if the wave table gets paged
out.
How are other AU developers dealing with this to avoid drop outs?
Not necessarily, though could be - with correct preparation the
DLSMusicDevice unit that we ship doesn't exhibit this problem.
Bill
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