Re: Setting AudioQueue input device and format?
Re: Setting AudioQueue input device and format?
- Subject: Re: Setting AudioQueue input device and format?
- From: Rick Mann <email@hidden>
- Date: Thu, 10 Mar 2011 17:32:34 -0800
On Mar 10, 2011, at 17:17:50, Brian Willoughby wrote:
>
> On Mar 10, 2011, at 14:25, Rick Mann wrote:
>> Format: I want the data in the exact same format that it comes out of the device. The Programming Guide first has me set a recording audio format, and then create the audio queue and ask it for the input format. What's the right way to ensure that the data in the buffers I get is the exact data output by the device?
>
> I would suggest that the most important aspect of the format is the sample rate. Make sure your graph is processing at the native rate of your input hardware. Apart from that, there really is no advantage to working in 16-bit just because the input data is 16-bit. It's perfectly fine to convert any input format to 32-bit float and leave it at that. The rest of your math will be much simpler with float, and you'll also have access to all of the existing AudioUnits that are designed for the canonical format.
>
> Again, only the sample rate is important. Don't fret about the rest of the format details unless your device somehow delivers more than 25-bit fixed or 32-bit float.
Hmm, that's a good point. I'd still like to query the device for its sample rate, rather than making assumptions, and then set the rest of it for 32-bit float. Since I'm already writing code to get AudioObject properties, perhaps I can use that to figure out the sample rate? Or should I query the Audio Queue (I'm not yet sure I can create it without specifying any particular format).
--
Rick
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