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Today's Topics:
1. Re: SPDIF audio in DVD Player (Jeff Moore)
2. Re: Creating Aggregate Devices programmatically (Jeff Moore)
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Message: 1
Date: Mon, 25 Jul 2005 12:50:57 -0700
From: Jeff Moore <email@hidden>
Subject: Re: SPDIF audio in DVD Player
To: CoreAudio API <email@hidden>
Message-ID: <email@hidden>
Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed
When a device is switched to a non-mixable format, the HAL also
enforces hog mode (aka exclusive access to the device) in a first
come, first served way. So, what is likely going on here is that some
other process has acquired hog mode before the DVD Player can. This
leaves the DVD Player to fall back to non-encoded output on the
default device.
HALLab can tell you which process owns hog mode for your device.
Plus, it can do so without forcing the HAL to grab hog mode provided
you don't do any IO with the device in HALLab.
On Jul 23, 2005, at 12:28 PM, Fabian Renn wrote:
Dear list members,
i'm programming an audio driver for an external usb 2.0 device. The
device has a spdif connecter and i'd like dvd player to support it.
I added the audio format kIOAudioStreamSampleFormat1937AC3 to the
list of supported formats and i can select in the DVD player, yet
when i play a dvd it gives me the error message: 'digital audio
device no longer available switching to standard output!'. What
else do i need to implement that the dvd player will use my device
correctly? All other audio works fine.
Greetings from Germany
Fabian Renn
--
Jeff Moore
Core Audio
Apple
------------------------------
Message: 2
Date: Mon, 25 Jul 2005 12:55:13 -0700
From: Jeff Moore <email@hidden>
Subject: Re: Creating Aggregate Devices programmatically
To: CoreAudio API <email@hidden>
Message-ID: <email@hidden>
Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed
Creating a new aggregate device requires using the new AudioObject
APIs in Tiger and goes something like this:
1) Locate the base plug-in using
kAudioHardwarePropertyPlugInForBundleID. It has a bundle ID of
"com.apple.audio.CoreAudio".
2) Create a CFDictionary that describes the aggregate device you want
to create. The keys for the dictionary are in the Aggregate Device
section of <CoreAudio/AudioHardware.h>. Be sure to create a unique
UID.
3) Tell the base plug-in to create the aggregate device using
kAudioPlugInCreateAggregateDevice.
4) Presuming success, use kAudioHardwarePropertyDeviceForUID to get
the AudioDeviceID of the newly created aggregate device.
That's pretty much it. Let me know if you have any specific questions
about the process.
On Jul 23, 2005, at 4:54 PM, Dave Addey wrote:
Hi all,
Does anyone have any sample code showing how to create an aggregate
device entirely programmatically? Or is there some particular
documentation I should be looking at? Any ideas much appreciated :-)
Dave.
--
Jeff Moore
Core Audio
Apple
------------------------------
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End of Coreaudio-api Digest, Vol 2, Issue 220
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