Multiple data sources and kAudioStreamPropertyTerminalType
Multiple data sources and kAudioStreamPropertyTerminalType
- Subject: Multiple data sources and kAudioStreamPropertyTerminalType
- From: Edward Peterlin <email@hidden>
- Date: Fri, 8 Apr 2005 14:37:55 -0700
Greetings! I am working on an application and have been trying to
detect the terminal type for audio input devices. The hardware portion
of the application is compatible only with external line-level input
devices, so I have been using the kAudioStreamPropertyTerminalType to
query whether the audio device has streams with the
EXTERNAL_LINE_CONNECTOR terminal type.
For devices that have multiple data sources (such as the "Built-in
Audio" device) I've been trying to do this detection with the following
sequence:
- loop over multiple data sources
- set the kAudioDevicePropertyDataSource to flip data source for device
- query the kAudioDevicePropertyStreams property of the device to get
input streams for the data source
- loop over streams, checking kAudioStreamPropertyTerminalType value
This works fine on my G5 tower; the digital in data source returns
SPDIF terminal type, the line-in returns LINE_CONNECTOR. On a test
AlBook 12", however, both the internal microphone and line-in data
sources advertise an INPUT_MICROPHONE terminal type, so it isn't
possible to distinguish which data source is the line level input.
Does the above procedure seem sane and, if so, any thoughts as to why
it's not functional for the AlBook audio? I'm hoping to avoid doing
searches for a literal "Line" within the data source name since I
expect the data source names may be localized depending on the user's
preferred language setting.
Any help would be greatly appreciated!
regards,
Edward Peterlin
BIOPAC Systems, Inc.
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