Re: [iOS] kAudioUnitSubType_AUiPodTime and background audio
Re: [iOS] kAudioUnitSubType_AUiPodTime and background audio
- Subject: Re: [iOS] kAudioUnitSubType_AUiPodTime and background audio
- From: "Hank Heijink (Mailinglists)" <email@hidden>
- Date: Mon, 11 Oct 2010 11:03:51 -0400
Sorry to reply to my own post: I pasted one method into another to save space, and mistyped: wherever it says 'audioGraph', read 'mGraph'.
Apologies,
Hank
On Oct 11, 2010, at 10:47 AM, Hank Heijink (Mailinglists) wrote:
> 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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