Re: AUGraph reconfiguration in response to route change
Re: AUGraph reconfiguration in response to route change
- Subject: Re: AUGraph reconfiguration in response to route change
- From: Bartosz Nowotny <email@hidden>
- Date: Tue, 10 Jul 2018 20:53:58 +0200
Yes, I have tried AVAudioSession route change notification as well - same
result.
Even though the code can handle multiple AUMIDISynths, I have set it up so
that for testing only 1 is ever created.
There is definitely something weird going on: if I respond to the route
change and then try to play some notes - the app always crashes. If I plug
in my headphones while some notes are being played, it either continues to
play, goes to silence or crashes.
I have created a snippet that shows how my set up looks like:
https://hastebin.com/ugumilofid.m
At the top, you can find a brief explaination of what the included code is
supposed to do, what the test scenario is and what is the app output.
I am out of ideas as to what is wrong here. Is it possible that this is a
threading issue? Other than the route change handling the set up works
great: I can load up multiple soundfonts, play notes, unload soundfonts,
shut the graph down and then start it again later.
Regards,
Bartosz
On Tue, Jul 10, 2018 at 11:20 AM, Sven Thoennissen <email@hidden> wrote:
> Hello,
>
> It may have to do something with the property listener. Have you tried
> using AVAudioSession.routeChangeNotification instead?
> Did you connect more than 8 AUMIDISynth to your mixer? (IIRC 8 is the
> maximum possible, at least with AVAudioMixerNode)
>
> In any case it is hard to tell without seeing code. I recommend to set up
> a minimal test project with only 1 AUMIDISynth.
>
> Have you considered using AVFoundation classes instead of the old V2 API?
> (at least to reproduce the problem)
>
> Best regards,
> Sven
>
> > Am 09.07.2018 um 21:32 schrieb Bartosz Nowotny <email@hidden
> >:
> >
> > Hello,
> >
> > I am trying to programmatically reconfigure AUGraph at runtime, in
> response to a route change.
> >
> > My set up consists of a couple of AUMIDISynth nodes connected to a multi
> channel mixer node which in turn is connected to RemoteIO node. This set up
> works fine and I am able to produce audio by sending MIDI note on/off
> events.
> >
> > I want to avoid audio data resampling at any point in the graph. I can
> start with a properly set up AUGraph that has all audio units use the same
> sample rate (starting from midi synths, through mixer to remote IO). Route
> changes (e.g. plugging in headphones) can change the output sample rate and
> thus introduce resampling and other side effects.
> >
> > To respond to a route change I set up a property listener for
> StreamFormat on my IO unit. When the stream format changes, I call a method
> that reconfigures the AUGraph in the following manner:
> > 1. Stop the AUGraph
> > 2. Uninitialize the AUGraph
> > 3. Clear all graph connections
> > 4. Set mixer output sample rate (propagates to IO input sample rate)
> > 5. Set synth output sample rates (propagates to mixer input sample rates)
> > 6. Connect synth nodes to mixer node
> > 7. Connect mixer node to IO node
> > 8. Update, Initialize and Start the AUGraph
> >
> > None of the above operations returns an error result.
> >
> > The issue occurs when I send some note on/off events - the app crashes.
> What am I missing?
> >
> > Regards,
> > Bartosz Nowotny
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