Version: 1.0

Posted: 2005-03-07

Build Requirements: Xcode 1.5

Runtime Requirements: 10.3.6

View Source Code:

Download Sample (“SampleUSBAudioPlugin.zip”, 17.3K)
Download Sample (“SampleUSBAudioPlugin.dmg”, 70.9K)


Description

This is a sample AppleUSBAudio plug-in that performs a lowpass filtering (DSP) operation on audio streamed through an USB Device. Specifically, this plug-in uses a lowpass filter with a 400 Hz cutoff on streamed audio.

The AppleUSBAudio plug-in architecture allows an audio device manufacturer to insert host based signal processing designed to enhance the capabilities of their device. This method eliminates the need to clone the AppleUSBAudio driver and integrate device specific signal processing code, which will lose the incremental enhancements and bug fixes that Apple provides on a regular basis via Software Updates.

The AppleUSBAudio plug-in can perform any of the following functions on a class-compliant USB audio device:

* send a USB device request on the default control pipe (IOUSBDevRequest)

* process input samples as they are received by the device

* process output samples before they are sent to the device

* set a configuration application for the plug-in

Note: You must specify the unique vendorID/productID combination of the USB audio device within the sample project.

Document Revision History

Date Notes
2005-03-07USB audio plugin that performs a lowpass filtering operation on audio streamed through an audio USB Device.

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