Re(2): Available Audio Formats
Re(2): Available Audio Formats
- Subject: Re(2): Available Audio Formats
- From: "Sean Morrell" <email@hidden>
- Date: Mon, 08 Oct 2001 15:23:25 -0700
email@hidden writes:
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On Monday, October 8, 2001, at 11:03 PM, Sean Morrell wrote:
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> Does CoreAudio and
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> IOAudioFamily have a mechanism to support such dependencies? As an
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> alternate approach, could a device driver provide a custom configuration
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> dialog, opened by a host application through CoreAudio?
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This is definitely (at leat for me) a driver problem.
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The driver is free to export what is suited for the device as formats.
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You need to make a driver
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that returns only legal configs and the HAL APIs will export that
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without any problem. You may look
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at the USB audio driver code in Darwin to see how to populate a list of
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formats. If your device is a USB
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one, and ou want to reuse the Apple code for USB driver, you can
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subclass it.
The AppleUSBAudio driver does indeed add the allowable formats and sample
rates of any given channel. And this works fine if the device supports
all the channels run at each channel's highest bit depth and sample rate.
With our device however, we can't just add all possible formats and sample
rates of each channel. The device will certainly support the highest bit
depth and sample rate on any channel, but only one channel. For multiple
channels to be used, either the bit depth or sample rate must be lowered,
across ALL channels. I don't see the AppleUSBAudio driver coded to handle
this situation, where the available format and sample rate for any channel
is dependent on the current format and sample rate of other enabled
channels.
Does CoreAudio provide applications the ability to load a custom device
configuration dialog implemented by the driver?
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Laurent
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Laurent Cerveau
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Applications Engineering
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Apple Computer Inc.
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email@hidden