The ACI of the Xbox provides AC97. It's similar to the AMD-768 ACI, but it is accessed through MMIO instead. The datasheet for the AMD-768 can be found at https://web.archive.org/web/20060322081039/http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/24467.pdf .
The AC97 implementation only supports playback of 16-bit PCM stereo samples at 48kHz[FIXME].
- 0x110 PCM
- 0x170 SPDIF
Usage in DirectSound
AC97 is only used to receive buffers from the APU. [FIXME]