Hi Arshia,
I use Apple’s Audio Tool Box, everything I need is included in:

#include <AudioToolbox/AudioToolbox.h> 

I’m calling:

AudioUnitSetProperty(), AudioUnitInitialize(), AudioOutputUnitStart() etc..

-Dean

PS It’s only the iPad *PRO* gen 3 that’s giving me issues.

PSS Apple is asking for a demo program and to report this as a bug.

> On Nov 15, 2018, at 12:39 PM, Arshia Cont <[email protected]> wrote:
> 
> What service are you using to record your streams from RemoteIO? Extended 
> Audio File Services? Audio File Services? AVAudioEngine magic?
> 
> Reading your posts I have to buy a 3rd generation iPad! :) But know that if 
> the system’s sample rate is at 48Khz and you are using 44.1khz, depending on 
> the recording service you use, additional converter services will be 
> introduced on the way to adapt services. And depending on your setup, it will 
> consume resources and if your BufferDuration is low then you get glitches! 
> Another source of glitch is of course if your Stream Formats do not comply 
> (which again depending on services used can introduce additional cycle 
> consuming converters that you don’t “see”). 
> 
> You can “see” them if you run your App on device and use Instrument’s “Time 
> Profiler”. Just take a sample of runtime during recording and find the 
> process that is taking too much time! Doing this you can sometimes find 
> amazing things under the hood that you are introducing without wanting or 
> not-recommended live DSP practices that you just missed (such as calling 
> Shared singletons which cause glitches if called in the audio thread).
> 
> Curious to know what you find until I receive my new iPad! :)
> 
> Cheers,
> 
> 
> Arshia
> 
>> On 15 Nov 2018, at 16:35, Dean Reyburn <[email protected] 
>> <mailto:[email protected]>> wrote:
>> 
>> A follow up:
>> 
>> My iPhone XS Av session has a sampleRate of 48khz, however this device 
>> records with a lot of distortion at 48khz. At 44.1khz the iPhone records 
>> perfectly.
>> 
>> So I’m still searching for a way to determine a reliable distortion free 
>> recording rate on all devices. For now I can use 48khz only with the 
>> “iPad8,x” but that’s a hack and the wrong way to do this in the long run.
>> 
>> FWIW I’m using the play and record av session type.
>> 
>> -Dean
>> 
>>> On Nov 14, 2018, at 4:52 PM, Martin Man <[email protected] 
>>> <mailto:[email protected]>> wrote:
>>> 
>>> Hi Dean,
>>> 
>>> What’s the 
>>> https://developer.apple.com/documentation/avfoundation/avaudiosession/1616499-samplerate?language=objc
>>>  
>>> <https://developer.apple.com/documentation/avfoundation/avaudiosession/1616499-samplerate?language=objc>
>>>  reporting back to you?
>>> 
>>> Martin (still unable to test on 11”)
>>> 
>>> 
>>>> On 14 Nov 2018, at 14:24, Dean Reyburn <[email protected] 
>>>> <mailto:[email protected]>> wrote:
>>>> 
>>>> Hi Pascal,
>>>> I have found a possible solution for my recording (only) app which was 
>>>> giving distortion on iPad Pro gen 3 .  My older versions record only at 
>>>> 44.1khz. When I change to 48khz the recording is perfect. Either sample 
>>>> rate works fine for my app, but I simply need to know during 
>>>> intitialization which to use.
>>>> 
>>>> I’m still talking to Apple DTS about how to detect whether a device wants 
>>>> or needs 44.1khz or 48khz. There are no error returned when an iPad Pro 
>>>> gen 3 from AudioUnitSetProperty() or any other audio units call on iPad 
>>>> Pro 3 when starting recording. The iPad Pro 3 accepts 44.1khz and confirms 
>>>> that it can do this sample rate with AudioUnitGetProperty() even though 
>>>> the recording is distorted.
>>>> 
>>>> So far I have not found how to detect the “default” or “native” recording 
>>>> sample rate for a device if such a thing exists.
>>>> 
>>>> -Dean
>>>> 
>>>>> On Nov 14, 2018, at 5:02 AM, Flavio Antonioli <[email protected] 
>>>>> <mailto:[email protected]>> wrote:
>>>>> 
>>>>> Pascal,
>>>>> 
>>>>> we have also received reports from some of our users of audio distortion 
>>>>> on the new iPad Pro. We too are using RemoteIO. 
>>>>> We don't currently have a device to test with so I wasn't able to 
>>>>> reproduce the issue.
>>>>> 
>>>>> Flavio.
>>>>> 
>>>>> On Tue, Nov 13, 2018 at 9:00 PM <[email protected] 
>>>>> <mailto:[email protected]>> wrote:
>>>>> Message: 2
>>>>> Date: Tue, 13 Nov 2018 16:43:53 +0100
>>>>> From: Pascal Douillard <[email protected] 
>>>>> <mailto:[email protected]>>
>>>>> To: [email protected] <mailto:[email protected]>
>>>>> Subject: Audio cracks with the iPad 11"
>>>>> Message-ID: <[email protected] 
>>>>> <mailto:[email protected]>>
>>>>> Content-Type: text/plain; charset=utf-8
>>>>> 
>>>>> Hi everyone,
>>>>> 
>>>>> I have an audio app for iPad & iPhone and I have been getting audio 
>>>>> cracks on the new iPad Pro 11”. The cracks happen on speakers and on 
>>>>> headphones on the USB-C port but not when using bluetooth headphones like 
>>>>> the Air Pods.
>>>>> 
>>>>> They do not happen on any of the other iPads or iPhone. 
>>>>> 
>>>>> The audio engine is in C++ and is running in Core Audio using a single 
>>>>> RemoteIO unit. No extra audio libraries are used.
>>>>> 
>>>>> This is not related to the forced 48K sample rate of the iPad 11” as the 
>>>>> app runs fine with the same sample rate on other devices.
>>>>> 
>>>>> Anyone else has experienced the same? Thanks.
>>>>> 
>>>>> Pascal
>>>>> 
>>>>> ------------------------------
>>>>> 
>>>>> Subject: Digest Footer
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