This file explains the codec-specific mixer controls.
Realtek codecs
Channel Mode
This is an enum control to change the surround-channel setup,
appears only when the surround channels are available.
It gives the number of channels to be used, “2ch”, “4ch”, “6ch”,
and “8ch”. According to the configuration, this also controls the
jack-retasking of multi-I/O jacks.Auto-Mute Mode
This is an enum control to change the auto-mute behavior of the
headphone and line-out jacks. If built-in speakers and headphone
and/or line-out jacks are available on a machine, this controls
appears.
When there are only either headphones or line-out jacks, it gives
“Disabled” and “Enabled” state. When enabled, the speaker is muted
automatically when a jack is plugged.When both headphone and line-out jacks are present, it gives
“Disabled”, “Speaker Only” and “Line-Out+Speaker”. When
speaker-only is chosen, plugging into a headphone or a line-out jack
mutes the speakers, but not line-outs. When line-out+speaker is
selected, plugging to a headphone jack mutes both speakers and
line-outs.
IDT/Sigmatel codecs
Analog Loopback
This control enables/disables the analog-loopback circuit. This
appears only when “loopback” is set to true in a codec hint
(see HD-Audio.txt). Note that on some codecs the analog-loopback
and the normal PCM playback are exclusive, i.e. when this is on, you
won’t hear any PCM stream.Swap Center/LFE
Swaps the center and LFE channel order. Normally, the left
corresponds to the center and the right to the LFE. When this is
ON, the left to the LFE and the right to the center.Headphone as Line Out
When this control is ON, treat the headphone jacks as line-out
jacks. That is, the headphone won’t auto-mute the other line-outs,
and no HP-amp is set to the pins.Mic Jack Mode, Line Jack Mode, etc
These enum controls the direction and the bias of the input jack
pins. Depending on the jack type, it can set as “Mic In” and “Line
In”, for determining the input bias, or it can be set to “Line Out”
when the pin is a multi-I/O jack for surround channels.
VIA codecs
Smart 5.1
An enum control to re-task the multi-I/O jacks for surround outputs.
When it’s ON, the corresponding input jacks (usually a line-in and a
mic-in) are switched as the surround and the CLFE output jacks.Independent HP
When this enum control is enabled, the headphone output is routed
from an individual stream (the third PCM such as hw:0,2) instead of
the primary stream. In the case the headphone DAC is shared with a
side or a CLFE-channel DAC, the DAC is switched to the headphone
automatically.Loopback Mixing
An enum control to determine whether the analog-loopback route is
enabled or not. When it’s enabled, the analog-loopback is mixed to
the front-channel. Also, the same route is used for the headphone
and speaker outputs. As a side-effect, when this mode is set, the
individual volume controls will be no longer available for
headphones and speakers because there is only one DAC connected to a
mixer widget.Dynamic Power-Control
This control determines whether the dynamic power-control per jack
detection is enabled or not. When enabled, the widgets power state
(D0/D3) are changed dynamically depending on the jack plugging
state for saving power consumptions. However, if your system
doesn’t provide a proper jack-detection, this won’t work; in such a
case, turn this control OFF.Jack Detect
This control is provided only for VT1708 codec which gives no proper
unsolicited event per jack plug. When this is on, the driver polls
the jack detection so that the headphone auto-mute can work, while
turning this off would reduce the power consumption.
Conexant codecs
- Auto-Mute Mode
See Reatek codecs.
Analog codecs
Channel Mode
This is an enum control to change the surround-channel setup,
appears only when the surround channels are available.
It gives the number of channels to be used, “2ch”, “4ch” and “6ch”.
According to the configuration, this also controls the
jack-retasking of multi-I/O jacks.Independent HP
When this enum control is enabled, the headphone output is routed
from an individual stream (the third PCM such as hw:0,2) instead of
the primary stream.
