Re: AU HostCallback - musical location
Re: AU HostCallback - musical location
- Subject: Re: AU HostCallback - musical location
- From: Marc Poirier <email@hidden>
- Date: Wed, 2 Oct 2002 14:59:44 +0200 (CEST)
>
If beat/tempo/etc information is NOT applicable when an AU calls for that
>
information (lets say that you're processing live input and thus the host
>
may have no concept of beats and tempo) - then the host returns an error
>
code from either of these callbacks.
>
>
The error code returned would be:
>
kAudioUnitErr_CannotDoInCurrentContext = -10863
Great, sounds like a good way to handle this with what is already in place
(or to be in place).
>
typedef OSStatus (*HostCallback_GetMusicalTimeLocation) (
>
void *inHostUserData,
>
UInt32 *outDeltaSampleOffsetToNextBeat,
>
Float32 *outTimeSig_NumBeats,
>
UInt32 *outTimeSig_BeatType,
>
Float64 *outCurrentMeasureDownBeat,
>
UInt32 *outFlags);
>
>
// where flags can have one of the following values
>
enum {
>
kMusicalTimeLocation_NewPlaybackPostion = (1L << 0)
>
//playback position has JUMPED - is not contiguous from previous call
>
};
Sounds good, and good to have a flags variable present for future
extension...
>
The AU has to know about the time sig and the tempo if its doing anything
>
with them. As these are passed in directly, it is easy enough to determine
>
that its different than the last time this has changed.
Okay, it would be a nicety, but not anything crucial...
Thanks again for taking these issues into consideration and improving
things!
Marc
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