ac97 —
generic AC'97 codec driver
AC'97 codecs contain the analog to digital (A/D), digital to analog (D/A), and
mixing circuitry of many modern sound cards. AC'97 codecs, for the most part,
do not talk to host buses like the PCI bus directly. Instead, they communicate
through an interface chip, called the host controller. The Ensoniq AudioPCI 97
(see
eap(4)) is an example of such
a host controller.
Unlike many drivers, the
ac97 driver does not
appear in the configuration file. Instead, the driver is automatically
attached by the drivers that require it.
auacer(4),
auich(4),
auixp(4),
autri(4),
auvia(4),
clcs(4),
clct(4),
eap(4),
emu(4),
esa(4),
fms(4),
maestro(4),
neo(4),
yds(4)
The
ac97 driver does not keep track of the
current user settings and instead relies on the hardware to do this.
The
ac97 driver could do more to detect mixer
channels that don't work and cull them from the list.
![[OpenBSD]](/openbsd.gif){kind=small}