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Re: Purpose of kAudioDevicePropertyChannelNumberNameCFString
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Re: Purpose of kAudioDevicePropertyChannelNumberNameCFString


  • Subject: Re: Purpose of kAudioDevicePropertyChannelNumberNameCFString
  • From: Chris Thomas <email@hidden>
  • Date: Tue, 2 Jan 2007 23:38:38 -0500

These names are statically allocated. For both drivers in question, you should be able to check them in Terminal by invoking ioreg with the IOAudioEngine subclass name:

$ ioreg -n com_m_audio_FWEngine2
[...]
+-o com_m_audio_FWEngine2 [...]
| | "IOAudioEngineChannelCategoryNames" = {"InputChannel2"="Input Analog","OutputChannel1"="Output Analog","OutputChannel4"="Output Analog","InputChannel3"="Input S/P$
| | "IOAudioEngineChannelNames" = {"InputChannel2"="Input Analog 2","OutputChannel1"="Output Analog 1","OutputChannel4"="Output Analog 4","InputChannel3"="Input S/PDI$
| | "IOAudioEngineChannelNumberNames" = {"InputChannel2 "= "2 ","OutputChannel1 "="1","OutputChannel4"="4","InputChannel3"="1","OutputChannel2"="2", [...]


Chris

On Dec 21, 2006, at 3:37 PM, Jeff Moore wrote:

I suppose it could be any of the three bits of code could have a bug, but my first suspicion would fall on the driver.

On Dec 21, 2006, at 12:29 PM, email@hidden wrote:

Yes, your example shows what I was expecting to see based on the comments in the include file. However, what I am observing with my 2 examples is that the Number name is the same as the category name. So, for example if the Category name is "Analog outputs", each channel's number name is also "Analog outputs" with no difference for each channel. It is possible that there is a bug in my program, the device driver(s) for the (2) devices, or in the CA API.

Jeff Moore wrote:
The number name is used in conjunction with the category name to allow you to label a bank of things. For example, here's a bank of sliders labled with the category and each slider labeled with the number (pardon my ascii art):
----- Category ----
| | |
| | |
+ + +
| | |
| | |
Number Number Number
On Dec 21, 2006, at 7:27 AM, email@hidden wrote:
In my simple host program I've started to query the Name properties for my output devices. I have 2 Firewire devices, Digidesign MBox 2 Pro and M-Audio FireWire Audiophile. On both of these devices, the ChannelName, ChannelNumberName and ChannelCategoryName properties are available in the Output section. However, ChannelNumberName and ChannelCategoryName seem to be always returning identical strings (to each other), for every channel. The properties are not available on the Built-in audio.

I was expecting a string such as "1" or "One" for the ChannelNumberName on Channel 1. What is the expected behavior? HALLab does not seem to display these properties.


--

Jeff Moore
Core Audio
Apple


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