AC97

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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 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 audio (MP3) or video (Xvid) codec in a media player.

Audio components integrated into Intel chipsets consists of 2 components - an AC'97 digital controller (DC97), which is built into the I/O Controller Hub (ICH) of the chipset, and an AC'97 audio and modem codecs, 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In 2004 AC'97 was superseded by Intel High Definition Audio (HD Audio).

1 AC-Link
2 Codec chips
3 See also
4 External link

[edit] AC-Link

The AC-Link is a bidirectional, fixed rate (12.288MHz), 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.

[edit] 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), VT82C686
Winbond W83971
Wolfson Microelectronics 9701, 9703, 9704, 9705 (w/touchscreen), 9707, 9708, 9709 (DAC only), 9711, 9712 (w/touchscreen), 9713 (w/touchscreen), 9714