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Re: Using AudioDeviceRead?
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Re: Using AudioDeviceRead?


  • Subject: Re: Using AudioDeviceRead?
  • From: Bill Stewart <email@hidden>
  • Date: Sat, 1 Mar 2003 17:57:56 -0800

Dirk

On Friday, February 28, 2003, at 08:16 AM, Dirk Musfeldt wrote:

Hi, Jeff,

I found out that the problem was 10.1.5... The same code works like a charm
on 10.2.

Is there any chance to get AudioDeviceRead working on 10.1.5?

Not very likely... (snow flakes and a hot place come to mind:)

Bill



With kind regards

Dirk Musfeldt
Meilenstein Mac OS Software

Neue Strasse 5
D-31582 Nienburg
Germany
Tel: +49 (0) 5021 91 24 44
Fax: +49 (0) 5021 91 24 45
<http://www.meilenstein.de/>


Von: Jeff Moore <email@hidden>
Datum: Wed, 19 Feb 2003 12:04:15 -0800
An: email@hidden
Betreff: Re: Using AudioDeviceRead?

On Wednesday, February 19, 2003, at 04:21 AM, Dirk Musfeldt wrote:

Hi Jeff,

Have you started the device you are reading from?

I double-checked the IDs used with the various AudeDeviceXXX calls and
they
matched.

But have you actually called AudioDeviceStart on the device you are
going to read from? This is absolutely required in order to engage the
device's timing services. You can pass NULL as the IOProc to just start
things up if you don't have an IOProc.

Is the address of the AudioBufferList you are passing to
AudioDeviceRead() the same as the one that you registered with
kAudioDevicePropertyRegisterBufferList?

I double-checked the addresses of the AudioBufferList and they
matched, too.

Does the device you are reading from really have inputs?

I checked that.

Is the time stamp valid and for a time far enough in the past?

Maybe that could be the error. I start with

AudioDeviceGetCurrentTime()
- AudioDeviceGetProperty (... kAudioDevicePropertySafetyOffset ...)
- totalReadBufferLength / frameSize

Does that make sense?


That should be reasonable, except if the device isn't running, you
won't be getting valid time stamps.

You should also take a look at the PlayEffect sample code to see an
example of how it's done.

--

Jeff Moore
Core Audio
Apple
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