Re: AudioUnitParameterUnit requests
Re: AudioUnitParameterUnit requests
- Subject: Re: AudioUnitParameterUnit requests
- From: Franck STAUFFER <email@hidden>
- Date: Fri, 18 Oct 2002 22:05:33 +0200
Ok here is my opinion on this changes..
Le vendredi, 18 oct 2002, ` 21:47 Europe/Paris, Bill Stewart a icrit :
OK
Here is the definition of these parameter unit type constants:
kAudioUnitParameterUnit_Octaves = 21,
/* octaves in relative pitch where a value of 1 is equal to 1200
cents*/
kAudioUnitParameterUnit_BPM = 22,
/* beats per minute, ie tempo */
kAudioUnitParameterUnit_Beats = 23,
/* time relative to tempo, ie. 1.0 at 120 BPM would equal 1/2 a second
*/
kAudioUnitParameterUnit_Milliseconds = 24
/* parameter is expressed in milliseconds */
The only area to clear up is what kind of parameter range do you
expect an
octave param to express - we're presuming that this parameter
indicates a
*relative* value - where 1 would change the parameter value UP an
octave,
and -1 would change the parameter value DOWN an octave... Fractional
values?
(If so 0.5 would be half an octave - ie. Equivalent to 600 cents)?
I use that kind of unit for filter bandwidth so usually is use, but
relative is probably the best solution...and of course I think it
should accept non integer values...(for instance I use 0.0f-2.0f for my
bandpass filters).
We thought we'd add one while we were at this...
A parameter unit type of the _BPM means that the delay will be timed
off 120
beats per minute. If the audio unit is able to get Tempo/beat
information
from the host, then the AU could decide to maintain the BPM value from
the
host, or allow a separate BPM to be set by the user.
Good Move :)
This then describes how that parameter will relate its timing to the
tempo.
Here, we're expecting that a value of "1" means that the parameter is
timed
to a beat (as expressed by _BPM - whether this is maintained by the
host
tempo or set by the user), a value of "2" means the parameter is timed
at 2
beats, a value of "0.5" means its timed at a half a beat, etc...
yeah that's an interesting thing to take account of the time
signature...it took me 2 minutes to understand the meaning of that
parameter, but I just came back from work so it's probably normal.
Anyway, overall this is the change I'd expect as far as tempo/timing is
concerned.
Take Care,
Franck
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