Re: [iOS] kAudioUnitSubType_AUiPodTime and background audio
Re: [iOS] kAudioUnitSubType_AUiPodTime and background audio
- Subject: Re: [iOS] kAudioUnitSubType_AUiPodTime and background audio
- From: "Roni Music" <email@hidden>
- Date: Wed, 13 Oct 2010 09:04:37 +0200
Maybe you need to set
kAudioUnitProperty_MaximumFramePerSlice to 4096
as described in:
http://developer.apple.com/library/ios/qa/qa2009/qa1606.html
Rolf Nilsson / Roni Music
Hi all,
I have an application that plays audio through an AUGraph, and I've hit a
bump in the road. Here's how the graph is set up:
AudioComponentDescription outputDesc = {kAudioUnitType_Output,
kAudioUnitSubType_RemoteIO, kAudioUnitManufacturer_Apple, 0, 0};
AudioComponentDescription mixerDesc = {kAudioUnitType_Mixer,
kAudioUnitSubType_MultiChannelMixer, kAudioUnitManufacturer_Apple, 0, 0};
AudioComponentDescription iPodTimeDesc = {kAudioUnitType_FormatConverter,
kAudioUnitSubType_AUiPodTime, kAudioUnitManufacturer_Apple, 0, 0};
AUGraph mGraph;
NewAUGraph(&mGraph);
AUNode outputNode;
AUNode mixerNode;
AUNode iPodTimeNode;
AUGraphAddNode(audioGraph, &outputDesc, &outputNode);
AUGraphAddNode(audioGraph, &mixerDesc, &mixerNode);
AUGraphAddNode(audioGraph, &iPodTimeDesc, &iPodTimeNode);
// These two lines are what will be replaced below
AUGraphConnectNodeInput(audioGraph, mixerNode, 0, iPodTimeNode, 0);
AUGraphConnectNodeInput(audioGraph, iPodTimeNode, 0, outputNode, 0);
AUGraphOpen(audioGraph);
...etc...
I left out the rest of the stuff, because the problem seems to exhibit
itself here - let me know if you think that's relevant...
When I play audio through this graph on an iPhone 4 (iOS 4.1), audio plays
fine but stops as soon as the screen goes blank or I hit the sleep button
on the top of the iPhone. However, if I take out the iPod time unit by
replacing the two lines referenced above with this:
AUGraphConnectNodeInput(audioGraph, mixerNode, 0, outputNode, 0);
audio keeps playing, even after the screen goes blank or if I hit the
sleep button. This is the behavior I want. I verified that the audio
category is right (kAudioSessionCategory_MediaPlayback), and everything
else seems to be just fine: no errors are returned by any of the setup or
rendering functions/callbacks. I've looked on the developer forums, the
archives, and google in general and I haven't found anything about this.
Has anybody else seen this behavior? Any input would be greatly
appreciated!
Thanks,
Hank
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