Re: Reading and writing from/to sound devices without AU
Re: Reading and writing from/to sound devices without AU
- Subject: Re: Reading and writing from/to sound devices without AU
- From: Rick Mann <email@hidden>
- Date: Wed, 09 Mar 2011 22:52:59 -0800
On Mar 9, 2011, at 20:30:28, Brian Willoughby wrote:
>
> On Mar 9, 2011, at 20:12, Rick Mann wrote:
>> On Mar 9, 2011, at 20:01:43, Kyle Sluder wrote:
>>> On Wed, Mar 9, 2011 at 7:18 PM, Rick Mann <email@hidden> wrote:
>>>> I already wrote some code as an Audio Unit, and that works fine. But there are times when I want to process the incoming data (which happens to be in the audio spectrum, of sorts, but isn't necessarily audio data) and produce something that is distinctly NOT audio. In this case, I won't be outputting any sounds, and Core Audio won't be calling me to ask for samples.
>>>
>>> Well, you could just terminate your AU graph with a GenericOutput
>>> unit. That'll pull samples through the graph but not drive any audio
>>> device.
>>
>> That's a thought. Still seems a little hackish. I'll take a look at the GenericOutput unit.
>
> It's not necessarily a hack. What you describe, Rick, is not much different than an audio recording application which is not producing sound at the same time, and there are certainly examples of this in the commercial world. The fact that your input data comes from an audio device makes it even less of a hack.
>
> Really, your data represents audio frequency signals, and thus AUGraph or any of the other pieces of CoreAudio would be perfectly suitable. You don't necessarily need AudioUnits, but you might find some of the existing filters to be useful, and will save you on coding time. I'm not suggesting that you go out of your way to use CoreAudio, but it should represent the easiest solution, despite the oddness of your SDR data.
Well, you might be right about that. I think I'll do the experiment with Audio Queues, and see how that appears. I would like to use a band-pass filter on the portion of spectrum brought down to 96 kHz by the receiver. I *think* I need to mix that spectrum further to get what I really want, but I haven't figured that part out yet.
--
Rick
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