Thanks!

I’ll give it a shot.

-Kenny


> On Apr 18, 2018, at 4:09 PM, Stephen F. Booth <[email protected]> wrote:
> 
> I believe you're after kAudioDevicePropertyNominalSampleRate.
> 
> See https://developer.apple.com/library/content/qa/qa1196/_index.html 
> <https://developer.apple.com/library/content/qa/qa1196/_index.html> for a 
> code sample and more information.
> 
> Stephen
> 
> On Wed, Apr 18, 2018 at 5:33 PM Kenny Leung <[email protected] 
> <mailto:[email protected]>> wrote:
> Yes it does, just like any other audio output device. That’s not my issue. 
> The issue is how to make the OS output to that device at the desired bitrate 
> programmatically. I know I can change the bitrate in Audio Midi Setup 
> manually.
> 
> -Kenny
> 
> 
>> On Apr 18, 2018, at 2:37 PM, Patrick Cusack <[email protected] 
>> <mailto:[email protected]>> wrote:
>> 
>> 
>> 
>>> On Apr 18, 2018, at 2:25 PM, Kenny Leung <[email protected] 
>>> <mailto:[email protected]>> wrote:
>>> 
>>> Hi Patrick.
>>> 
>>> I’m trying to write my own hi-res audio player. I’ve already been 
>>> successful in playing a 24/192kHz audio file on both iOS and macOS using 
>>> code based on what is written here: 
>>> https://developer.apple.com/library/content/documentation/MusicAudio/Conceptual/AudioQueueProgrammingGuide/AQPlayback/PlayingAudio.html
>>>  
>>> <https://developer.apple.com/library/content/documentation/MusicAudio/Conceptual/AudioQueueProgrammingGuide/AQPlayback/PlayingAudio.html>
>>> 
>>> However, the CoreAudio system automatically converts the sample rate 
>>> internally to whatever the output rate is set to (via Audio Midi Setup on 
>>> Mac, and some unknown method on iOS).
>>> 
>>> On iOS, you can set AVAudioSession.sampleRate, but output still won’t go 
>>> higher than 48kHz.
>>> 
>>> I’m using an XDuoo XD-05 
>>> (http://www.xduoo.com/xduoo/En/ProductView.Asp?ID=17 
>>> <http://www.xduoo.com/xduoo/En/ProductView.Asp?ID=17>) with a display, so 
>>> it tells me what the phone is outputting. I can use Onkyo player to play at 
>>> 24/192kHz, but I can’t get my own app to play at any more than 48kHz. 
>>> Sample rate conversion is precisely the thing I am trying to get away from.
>> 
>> Does the XDuoo shows up as an output device in OSX? Specifically in the 
>> Sound system preferences? 
>> 
>>> 
>>> Thanks.
>>> 
>>> -Kenny
>>> 
>>> 
>>>> On Apr 18, 2018, at 12:12 PM, Patrick Cusack <[email protected] 
>>>> <mailto:[email protected]>> wrote:
>>>> 
>>>> Your output device is going to determine your sample rate. Any audio you 
>>>> play is going to be float so 24 bit isn’t a consideration as you will 
>>>> convert the 24bit audio to float. As for your 192kHz audio, you will 
>>>> either need to play it out of 192kHz device or perform sample rate 
>>>> conversion in your audio graph.
>>>> 
>>>> This stack overflow listing discusses handling sample rate conversion:
>>>> 
>>>> https://stackoverflow.com/questions/6610958/os-x-ios-sample-rate-conversion-for-a-buffer-using-audioconverterfillcomplex
>>>>  
>>>> <https://stackoverflow.com/questions/6610958/os-x-ios-sample-rate-conversion-for-a-buffer-using-audioconverterfillcomplex>
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