Audio Codec '97

AC ‘97 Component Specification Revision 2.3 Rev 1.0
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• Amplified analog stereo headphone output (HP_OUT) transmitted to headphones or headset via stereo
mini-jack.
• Discrete analog 6-channel output (LINE_OUT plus 4CH_OUT) transmitted to Front and Surround
amplified stereo PC speaker arrays via three stereo mini-jacks.
• Analog matrix-encoded Surround output (such as Dolby ProLogic**) transmitted via stereo line level
output jack (LNLVL_OUT) or an amplified output (AUX_OUT or HP_OUT) to consumer A/V equipment
that drives a home theater multi-speaker array.
• Digital 5.1 channel output (such as Dolby Digital** AC-3) transmitted via S/PDIF (SPDIF_OUT) to
digital ready consumer A/V equipment which drives a home theater multi-speaker array.
1.5 Driver Support for AC ‘97 Controller/Codec Interoperability
As mentioned previously, this specification does not explicitly define the companion AC ‘97 Digital Controller
component. However, any driver written for an AC ‘97 Controller/Codec pairing is responsible for exposing and
managing an AC ‘97 Codec’s features. Cross-vendor Controller/Codec interoperability requires that, at a minimum,
an AC ‘97 driver identifies and supports the following AC ‘97 feature set:
• 16-bit stereo output  slot 3&4 signaling, sample rate conversion (SRC), and DACs
• 16-bit mono or stereo input  slot 3&4 signaling, SRC, ADCs, and microphone selection, boost/gain
• AC ‘97 mixer  analog input sources, levels and mutes, LINE_OUT and AUX_OUT levels
• Power management
Every AC ‘97 Controller/Codec pairing must include the capability (in either the Controller, Codec, or driver) to
perform high quality
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digital SRC in support of stereo output and input at the following sample rates. For
mainstream PC systems, it is recommended that every AC ‘97 Controller/Codec pairing include this SRC capability
in hardware:
• 8.0, 11.025, 16.0, 22.05, 32.0, 44.1, and 48 kHz
It is also recommended that all AC ‘97 drivers support the following common
optional AC ‘97 features, when
determined to be present in the AC ‘97 Codec:
• Tone control
• SRC for the rates listed above
• Loudness
• 3D stereo enhancement
• AUX_OUT configured as true line level or headphone output
Other optional features may require specific support in the AC ‘97 Controller. In these cases interoperability may be
limited to an AC ‘97 Controller/Codec pairing where the CODECs are sourced by the same vendor:
• Multichannel (4- or 6-channel) audio
• 20 bit sample size
• S/PDIF digital output
• Third ADC for dedicated voice input
• Modem ADC, DAC and GPIO
• Multiple audio Codecs
• Docking functionality
• Vendor-specific features
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AC ‘97 compliance requires that the digital SRC capability located in the Controller, Codec, or software driver
meet or exceed the following:
• ≥ 85 dB FS A dynamic range
• ≥ 17.64 kHz -3 dB frequency response
• ≤ -70 dB FS passband THD+N
• ≤ 0.5 dB passband ripple