RE: AudioDeviceRead / HALOutputUnit
RE: AudioDeviceRead / HALOutputUnit
- Subject: RE: AudioDeviceRead / HALOutputUnit
- From: "Tim Dorcey" <email@hidden>
- Date: Thu, 5 Feb 2004 10:55:46 -0800
My app captures audio from the default input device using
AudioDeviceAddIOProc()/AudioDeviceStart(). It uses
AudioDeviceAddPropertyListener() to listen for changes in
kAudioDevicePropertyStreamFormat and reconfigure an AudioConverter
accordingly. Captured audio is sent over network for a telephony like
application. It seems to work fine, although I am getting some reports of
spontaneous changes in input gain, and I haven't really examined
efficiency/performance (was just happy to have it working).
Should I be looking at using an Output AU for this? Or, do I misunderstand
the context of the discussion below?
Has anyone else seen apparently spontaneous changes in input gain? I guess
I could listen for changes in kAudioDevicePropertyVolumeScalar? But not
sure how I would tell the difference between a user desired change, and
whatever else may cause it.
Tim
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-----Original Message-----
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From: email@hidden
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[mailto:email@hidden]On Behalf Of Jeff Moore
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Sent: Wednesday, January 14, 2004 11:11 AM
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To: CoreAudio API
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Subject: Re: AudioDeviceRead / HALOutputUnit
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Yes, for two primary reasons:
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First, the Output AU does all the hard work of being a proper HAL
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client. There are a lot of details involved with this for a general
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applications, so the work saved by doing it is immense, especially if
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you are already using the Output AU for other things.
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Second, not every device supports AudioDeviceRead. Currently, the
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popular examples of devices that don't are Digi hardware and the
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iSight, and the future has more on the way.
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Generally speaking, I recommend that everybody use the AUs
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rather than
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using the HAL directly.
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On Jan 14, 2004, at 7:25 AM, Chandrasekhar Ramakrishnan wrote:
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> If one already has code that uses AudioDeviceRead to get audio input
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> that you feed into an AU graph, is there any reason to switch to the
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> HALOutputUnit input capabilities?
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