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AC'97 (short for Audio Codec '97) is Intel Corporation's Audio "Codec" standard developed by the Intel Architecture Labs in 1997, and used mainly in on-motherboards (also known as 'on-board' or 'integrated'), modems, and sound cards.

Intel's use of the word audio codec refers to signals being encoded/decoded to/from analog audio from/to digital audio, thus actually a combined audio AD/DA-converter. This should not be confused with a codec in the sense of converting from one binary format to another, such as an MP3 codec.

Audio components integrated into Intel chipsets consists of 2 components - an AC'97 digital controller, which is built into the I/O Controller Hub (ICH) of the chipset, and an AC'97 codec, which is the analog component of the architecture. AC'97 defines a high-quality, 16- or 20-bit audio architecture for the PC that is used in the majority of today's desktop platforms. AC'97 supports 96 kHz in 20-bit stereo resolution and 48 kHz in 20-bit stereo for multichannel recording and playback.

Integrated audio is implemented with the AC'97 Codec on the motherboard, a CNR (Communications and Networking Riser) card, or an AMR (Audio and Modem Riser) card.

AC '97 v2.3 enables Plug and Play audio for the end user. This version provides parametric data about the analog device being used.

In 2004 AC'97 was superseded by Intel High Definition Audio (HD Audio).



The AC-Link is a bidirectional, fixed rate, serial PCM digital stream. It handles multiple input and output audio streams and control registers access employing a time division multiplexing (TDM) scheme. The AC-Link architecture divides each audio frame into twelve outgoing and twelve incoming data streams, each with 20-bit sample resolution.

Codec chips

Codec chips have an (AC'97) interface on one side and analog audio interface on the other. They are usually small square chips with 48 pins. They are D/A and A/D or only D/A.

  • Analog Devices AD1881A, 1885, 1887, 1981, 1819B, 1881A, 1886, 1887, 1980, 1981, 1985
  • Asahi Kasei AK 4540, 4543, 4544A, 4545
  • Avance Logic (now Realtek) ALC201A, ALC650, ALC655, ALC101, ALC202A, ALC250
  • Conexant Cx20468 - with a modem
  • Cirrus Logic CrystalWare CS4297A, CS4299
  • Crystal 4205, 4202
  • C-Media CMI9738, 9739
  • ESS ES1988(with a modem)
  • Intersil HMP9701 (obsolete, 48kHz fixed samplerate)
  • National Semiconductor LM 4540, 43, 45, 46, 48, 49, 50
  • Philips UCB 1400 (with touchscreen controller)
  • Realtek ALC655, ALC850
  • SigmaTel C-Major STAC 9460 (D/A only), 9461, 9462, 9463, 9200, 9202, 9250, 9251, 9220, 9221, 9223, 9750
  • Silicon Image Si3024 (mono only)
  • TriTech Microelectronics TR28022, 28026
  • Yamaha YMF 743, 752, 753
  • VIA VT1612, VT1616 (VIA Six-TRAC Vinyl Audio)
  • Winbond W83971
  • Wolfson Microelectronics 9701, 9703, 9704, 9705 (w/ touchscreen), 9707, 9708, 9709 (DAC only), 9711, 9712 (w/ touchscreen), 9713 (w/ touchscreen), 9714

See also

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