OS X and iOS Kernel Programming

I/O Kit Audio Support

The IOAudioFamily handles audio in the kernel and facilitates the creation of drivers for audio hardware. The responsibility of an audio driver is conceptually very simple; it merely transfers data to and from the hardware on behalf of clients (much like any hardware driver). It is also responsible for performing actions like muting, controlling the volume, or other configurable attributes. Core Audio uses 32-bit floating-point format as its native audio format and because not all devices will support this, a driver must handle conversion to and from a format the hardware is able to handle. Figure 12-3 shows the hierarchy of classes that make up the IOAudioFamily.

Figure 12-3. IOAudioFamily classes

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