Re: kAudioUnitType_FormatConverter and locking the iPhone
Re: kAudioUnitType_FormatConverter and locking the iPhone
- Subject: Re: kAudioUnitType_FormatConverter and locking the iPhone
- From: Doug Wyatt <email@hidden>
- Date: Fri, 24 Apr 2009 07:38:41 -0700
On Apr 24, 2009, at 7:35 AM, Doug Wyatt wrote:
On Apr 24, 2009, at 7:08 AM, Evan Olcott wrote:
I've noticed a strange artifact when using the
kAudioUnitType_FormatConverter/kAudioUnitSubType_AUConverter in
iPhone OS 2.2.1.
I have an application that runs as kAudioSessionCategory_LiveAudio.
If the phone becomes locked by the user (by pressing the button at
the top), the kAudioUnitSubType_AUConverter will not render from
it's connections, but will instead continue to play it's last given
buffer in a loop. To the user, it seems as though the phone becomes
"stuck". The render messages to it's connected inputs (or render
callbacks) seem to stop altogether, but audio continues to play,
albeit from this stuck buffer.
Is this a bug or expected behavior for this category? Is there a
workaround (apps don't get messages for when the iPhone becomes
locked, so there's no real way for the application to respond to a
"locked" change like the kAudioUnitSubType_AUConverter seems to).
That AU doesn't know anything about the lock switch either. What
you're describing sounds like a bug somewhere else, whether in the
OS or your app I don't know...
Wait ... Come to think of it, one thing that changes when the screen
is locked is that your I/O cycle duration can be increased.
AUConverter would start getting pulled for more samples at a time. If
its max-frames-per-render-cycle is exceeded, its AudioUnitRender would
start returning an error to its caller and not write anything into the
output buffer...
Doug
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