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I have a device that needs USB audio support in MacOS 9, for which I am planning to write ASIO and USB audio drivers. I am just double checking to make sure I cannot use Apple's USB audio class driver with my ASIO driver. My undertanding is that if my device is a USB audio device it should match with the Apple USB audio driver. This driver then interfaces with the Sound Manager, so in other words the API to access the USB audio device then becomes the SOund Manager. In addition, if my output device is not a speaker, specifically as defined in the USB descriptors in the output terminal type, then it is not claimed by the system as the default output device. This would allow me to open it and talk to it via an ASIO driver. The input also would be available. Is this correct? The device needs to be switched between 16 and 24 bit. Can I use Sound Manager calls to set the bit depth, and would these calls translate to having the Apple USB audio interface driver select an alternate interface? In other words, alternate interfaces are used to change between different sample rates and bit depths, so I don't know how I could get Apple's audio class interface driver to select alternate interface #2, for example. If going through Sound Manager wouldn't work, would writing my own Composite driver (using the Apple example code) and then having it call USBExpertInstallInterfaceDriver with my desired alternate interface descriptor be a way to have the Apple audio class interface driver select an alternate interface? I guess the other issue would be latency, as this would add another buffer copy step to intput and output processing. I'd have to think about how much this would add... - jarrell _______________________________________________ usb mailing list | email@hidden Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/usb Do not post admin requests to the list. They will be ignored.
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