The audio section is compliant with the Intel AC'97 Rev 2.2 specification. It performs full-duplex 18-bit codec functions and supports variable sample rates from 8 to 48k samples/s with high signal to noise ratio. Optional AC'97 features include 3D sound enhancement, line-level outputs, stereo buffered headphone outputs, hardware sample rate conversion, primary/secondary mode operation and S/PDIF output. Headphone auto-detect, I2S output and headphone buffer on the mono output are included.