A response from someone here at Apple:

> Hello Steven,
> I'm Brad Ford, from the AVFoundation capture team.  We generally do not read 
> this list.  If you believe there's a bug in AVCaptureConnection, please file 
> a bug at bugreport.apple.com <http://bugreport.apple.com/> with sample code 
> that reproduces the problem.  FYI, the best place to get feedback from real 
> engineers on AVFoundation APIs is devforums.apple.com 
> <http://devforums.apple.com/>.  Find the appropriate forum and post there.  
> Many engineers monitor those forums.
> 
> Thanks!
> -B.

Greg

> On Nov 11, 2014, at 7:28 AM, Steven Clark <[email protected]> wrote:
> 
> I tried about a gazillion different things and found exactly one change that 
> makes the problem go away.
>  
> In the midst of setting up the AVCaptureSession, there was a property 
> assignment to set the frame rate (assign to 
> AVCaptureConnection.videoMinFrameDuration) which is deprecated but still 
> present.  Remove that assignment, everything works.
>  
> Note that the original symptom is that the *audio* crashes, and the cause is 
> in the setup of the *video* session.  It turns out that while the audio 
> initialization crashed the program, if I got around that (e.g. the 10% of the 
> time it didn’t crash), the video capture didn’t work – the program didn’t 
> crash, but no video was captured.
>  
> I’ve considered random scribbling in memory someplace from my application 
> since I began this investigation.  Evidence does not support that theory, 
> although it cannot (being practical) be disproven.
>  
> The need for weeks of experimentation when APIs change, and the rapid pace of 
> API change, are not giving me a positive feeling toward Apple.  It’s sad, 
> because they do a lot of really good stuff.
>  
> Steven J. Clark
> VGo Communications
>  
> From: R_Adams [mailto:[email protected] <mailto:[email protected]>] 
> Sent: Wednesday, October 29, 2014 2:41 PM
> To: Steven Clark
> Cc: [email protected] <mailto:[email protected]>
> Subject: Re: App works on iOS 7.1, fails on iOS 8.1
>  
> I’ve discovered that some upgrades from 8.0 to 8.1 may leave the keyboard in 
> a state where geometry is invalid and dismiss animation is missing.  If you 
> are doing any animation or view positioning base on the keyboard, turn “OFF” 
> split keyboard in settings.
>  
> Long shot
>  
>  
> On Oct 29, 2014, at 12:30 PM, Steven Clark <[email protected] 
> <mailto:[email protected]>> wrote:
> 
> 
> I have an overly complicated VOIP app that I recently upgraded from targeting 
> iOS 7.1 to iOS 8.1.  When built for 8.1, it runs fine on iOS 7.x but dies 
> about 90% of the time on iOS 8.1.
>  
> It contains a single VPIO Audio Unit.  The call AudioOutputUnitStart() fails, 
> returning -50 – which is, according to macerror, “error in user parameter 
> list”.  Sometimes, I see the following line in the output when it fails:
>  
> 2014-10-29 14:08:21.879 VGo Test 3[2145:888062] 14:08:21.878 ERROR:     
> [0x331649dc] >aurioc> 806: failed: -50 (enable 3, outf< 1 ch,  16000 Hz, 
> Int16> inf< 1 ch,  16000 Hz, Int16>)
>  
> I can decipher the channel formats, and they are what I set for the 
> application side of the VPIO unit.  Does anyone have a clue what “>aurioc> 
> 806” means?  I got nothing useful with Google.
>  
> When it works, everything seems to be fine.  I haven’t been able to find 
> anything different between when it works and when it doesn’t.
>  
> I threw in some code to print out a bunch of the Audio Unit’s properties just 
> before calling AudioOutputUnitStart(), and everything looks fine except 
> kAUVoiceIOProperty_VoiceProcessingEnableAGC.  AudioUnitGetProperty() returns 
> -50 when getting this property, when and only when AudioOutputUnitStart() 
> also returns -50.  About 9 other properties are all fine, though.
>  
> I’ve tried instantiating a new VPIO Audio Unit when AudioOutputUnitStart() 
> fails.  Its properties, including EnableAGC, all print out fine, and then the 
> app crashes.
>  
> If you don’t have any ideas related to these problems, perhaps you might know 
> of any Core Audio changes between 7.x and 8.1?  I found nothing interesting 
> in the official Apple release notes.
>  
> Thank you very much,
>  
> Steven J. Clark
> VGo Communications
>  
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