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Re: Rép : Problems implementing kAudioDevicePropertyIOProcStreamUsage property in a user-land CoreAudio device (2)
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Re: Rép : Problems implementing kAudioDevicePropertyIOProcStreamUsage property in a user-land CoreAudio device (2)


  • Subject: Re: Rép : Problems implementing kAudioDevicePropertyIOProcStreamUsage property in a user-land CoreAudio device (2)
  • From: Jeff Moore <email@hidden>
  • Date: Fri, 24 Oct 2008 10:45:21 -0700


On Oct 24, 2008, at 2:25 AM, Stéphane Letz wrote:

So I found out the application (iMovie HD version 6.0.3) that was causing some problems:

- If I set mData be set to NULL *and* mDataByteSize to 0 for a disabled stream then iTunes does not work

- if I set mData be set to NULL only and not changing mDataByteSize then iMovie is crashing.

It appears that mData has to be set to NULL *only* (not changing mDataByteSize) for streams where the IOProcStreamUsage property is actually used, otherwise (IOProcStreamUsage not used) then the mData has to be set to NULL *and* mDataByteSize set to 0.

Does this makes sense?


Yes. That makes perfect sense. The _only_ difference in the ABL you pass to an IOProc when a stream is deactivated is that the mData pointer is NULL in the AudioBuffer that corresponds to that stream. All the other fields should be exactly the same as they would be if all the streams are active.

BTW, the default state is to have all streams active. So if you never get the stream usage set for a given IOProc, you should assume that all streams should be active.


--

Jeff Moore
Core Audio
Apple


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 >Rép : Problems implementing kAudioDevicePropertyIOProcStreamUsage property in a user-land CoreAudio device (2) (From: Stéphane Letz <email@hidden>)

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