On OS X, your host may set a property on your Audio Unit enumerated as kAudioUnitProperty_HostCallbacks. The payload of the property is the struct HostCallbackInfo, which in turn has a set of C function callbacks. If that property is set by the host, you can extrapolate the playback state and current beat position by calling those functions. AUBase has a handy wrapper around all of this, of course.
Note: it is not guaranteed that a host who provides the struct will return all the information from the output parameters to the functions. I have been able to call this at the beginning of each render cycle on most hosts, and I believe this to be the standard way it is implemented. So you should only really need to call it before you render/process the samples per cycle. For the record, this struct also exists on iOS, but via the Inter-App Audio layer of the Audio Unit API. Hope that helps. --Christian On Thu, Jan 15, 2015 at 12:11 PM, Nick <[email protected]> wrote: > Hi > Is there a way to get a notification in audio unit that a host started > playback, and get a function called every metronome beat/or bar change? > Thank you > > _______________________________________________ > Do not post admin requests to the list. They will be ignored. > Coreaudio-api mailing list ([email protected]) > Help/Unsubscribe/Update your Subscription: > https://lists.apple.com/mailman/options/coreaudio-api/recapitch%40gmail.com > > This email sent to [email protected] _______________________________________________ Do not post admin requests to the list. They will be ignored. Coreaudio-api mailing list ([email protected]) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/coreaudio-api/archive%40mail-archive.com This email sent to [email protected]
