AEAudioController not delivering requested sample rate about theamazingaudioengine HOT 8 CLOSED

Hey @soareschen - Thanks for the kind words! Would you mind grabbing the latest changes and trying again? I believe @rklaver has identified and resolved the issue in my absence!

from theamazingaudioengine.

Hi @michaeltyson,

I guess @rklaver's patch would solve the problem, provided that the preferred hardware rate is guaranteed to be configurable after the audio session is activated.

What I don't understand is the followed snippet when the hardware sample rate setting failed. Why change the asbd's sample rate to the current hardware sample rate? I believe core audio would run just fine despite the asbd's sample rate is different from the current hardware sample rate?

Soares

from theamazingaudioengine.

That's updated because AEAudioController's audioDescription needs to reflect the audio description that's currently in use - if the sample rate achieved isn't the one requested, it needs to be updated to reflect what's actually in use. Otherwise it runs the risk of introducing audio artefacts due to the incorrect sample rate.

from theamazingaudioengine.

Actually, that's not entirely true: I haven't tested this, but the mixer may automatically perform sample rate conversion. I'm not sure, though.

from theamazingaudioengine.

The remoteIO unit performs any conversion needed, including sample rate,
depending on the audio descriptions set for the app-side of the unit.

That is: The stream format set on the output scope of element 1 (audio in) decides
the format you get when pulling audio from the hardware input. And the stream format set on the input scope of element 0 (audio out) decides the format you should write to the buffers for hardware output.

So, all you need to do is to tell it what format you wish to work with in
your app, and you don't need to care about the actual hardware format
(including sample rate, number of channels, etc..)

I thought this was what AEAudioController's audioDescription was for? Or
where exactly is that used, for the input format or output format? And is
the inputAudioDescription matching the actual hardware format, or the
client side format set on the output scope of element 1?

In a similar matter, the multichannel mixer unit performs conversion if the
stream format of the inputs are different than the stream format of the
output.

from theamazingaudioengine.

I think this might be a misconception on my part: I thought the hardware sample rate dictates what sample rate the IO unit delivers. If it has sample rate conversion facilities, then I've taken the wrong approach when the delivered hardware sample rate isn't the same as the requested one!

from theamazingaudioengine.

Fixed with SHA 7bdb02a

from theamazingaudioengine.

Thanks for fixing the issue. Glad that we resolved the confusion and found the right way to configure the ASBD.

from theamazingaudioengine.