Re: General question
Re: General question
- Subject: Re: General question
- From: Daniel Birns <email@hidden>
- Date: Tue, 4 Nov 2008 18:34:45 -0800
On Nov 4, 2008, at 6:21 PM, William Stewart wrote:
On Nov 4, 2008, at 5:10 PM, Daniel Birns wrote:
Two questions:
My application will do automatically change the (HAL/preamp) input
volume, and adjust for this later in the playback process. I could
use some advice about how best to accomplish this.
To take a simple example: During recording my input AudioUnit
determines that the volume needs to be higher. So I change the HAL
input volume (not the recorder trim value) up by, say 6 db at time
t. (I know most devices don't support this yet -- but the built-in
mic does, and I'm working with manufacturers on getting their
support.) Later, during playback, from time 0 to time t, I will
add automatically add 6 db gain to the audio. I need only record
the time (t) and the delta in volume (+6db) during the record
process, and I need to get this information back later during
playback or processing. Not a lot of data.
Questions:
1) Where can I store this volume adjustment (time/db) information?
In track automation? in some data chunk in the wav file? In midi
somehow?
2) Can an AudioUnit access HAL objects? For example, the audio
unit usually has an opaque input source. Can I discover what that
source is and operate on it?
nope - you have no idea where the input comes from - could be a
file, could be generated, could be from a mic, etc...
3) Does apple provide SDKs for GarageBand and/or Logic so I can
provide (non AU) plug-ins, if my product needs it for ease-of-use?
GB and Logic both host audio units
Right -- I understand -- the question was non AU plug-ins. For
example: apogee has a panel in Logic Pro. Do they have special
arrangements with apple.
The problem is, if I don't know where the input is coming from, if I
don't have access to what AUHAL has, if I need to host it, then some
sort of plug-in at the host level may be what I need.
The question is, how do I solve this problem: the AU has input
information which it will use to set input preamp levels. Is this
absolutely impossible?
Maybe one solution is for the AU panel to have a user interface to
indicate what the input is. But of course, this would be awful,
because it could be wrong, or it could have been right once, but it
was changed...
--Daniel
My eternal gratitude to the soul who is able to set me on the right
track :-)
--Daniel
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