From the ALSA wiki
Here is complete ordered mapping of the 45 SBliveMixer controls so please add any notes you may be aware of about these controllers and what they actually do for a SBlive card and/or LiveDrive. Just start typing whereever you see the word Unknown. - Mark Constable 20020711
A page for AudigyMixer has been started so I presume the mixer presets of the Audigy is different to the legacy SBlive, so check out the AudigyMixer page if you have a more recent SBlive card. - Mark Constable 20040501
Master volume control
Same as previous but mono (?)
Headphone LFE 1
Headphone Left channel (when muted audio goes to the left speaker, when unmuted no audio)
Headphone output volume
Headphone Center 1
Headphone Right channel (when muted audio goes to the left speaker, when unmuted no audio)
When muted, the Bass and Treble control is ignored
Bass intensity control
Treble intensity control
Same as wave output volume. However, this control also affects other digital sources, like the CD-SP/DIF connector and wavetable music, when played via the analogue front-out.
Left surround and right surround volume control (like Master, but for surround channels only) (Master does not affect surround volume).
Surround Digital Capture
Center speaker volume and/or toggle
LFE stands for Low Frequency Effects which is .1 in 5.1. On my card this does effect the volume of my sub at least in analog. I'm curious about headphone lfe... but I have no real idea. The KX drivers (for windows emu10k1) have a thing that controls the cutoff frequency and the volume output to the subwoofer..maybe that is it?
Wave sound output volume (front left and right) -- Is used as the volume level for input when the Mix device is picked as the capture device as well (PCM does not).
Record toggle for channel 14
Controls wave sound volume on line-out when in 2-channel mode(s). (When in 2-channel mode(s), the rear speaker jack is actually supposed to be line-out.) Is automatically zeroed when card enters 4-channel (surround sound) mode(s)?
Hardware MIDI synthesizer volume control
Record toggle for channel 19
Line in volume
LiveDrive Line in connector volume
Line LiveDrive Capture
Record toggle for channel 22
Line LiveDrive 1
Has some realation to the S/PDIF input on the LiveDrive. My DVR is connected via S/PDIF in, and I use this to control the input level for output to analog speakers. None of the capture controllers work for the S/PDIF in, but this playback control does.
CD audio volume (analog internal connector -- for digital internal connector, see IEC958 TTL)
Volume of mic to output to speakers.
Mic Boost (+20dB)
Increases gain in Mic input so you get a boost in mic recordings, specially if the recording voice and / or instrument are distant or low in volume.
An internal connector for TV or Video capture boards to control volume without external cables (same as normal CD Audio cables )
An internal connector for modem audio / Line output (same as normal CD Audio cables; same connector, different pinout!)
On the SBLive Classic (no bloody Value, Platinum, etc.), there are coaxial digital I/Os. This channel (obviously) controls those ports.
IEC958 Coaxial Capture
Record toggle for channel 30
Fiber Optic Input devices (normaly connected to the LiveDrive)
IEC958 Optical Capture
Record toggle for channel 32
IEC958 Optical Raw
This might be an input to allow the unprocessed incoming stream to be captured (perhaps to record non-audio data like AC-3 or DTS audio without the EMU10K chip mangling it first) -- this may also be the only known method to record an incoming 44.1KHz digital stream without it being resampled to 48k internally first (but this needs to be tested to find out for sure -- any volunteers?).
Volume control for the digital CD input.When using digital CD input the PCM control also changes the volume.
IEC958 TTL Capture
Record toggle for channel 35
Internal connector that provides volume control for the PC Speaker as long as its connected to the sound card
Auxilary (another internal connector) volume control. On a SBLive Value, this controls the level of the second (non-CD, non-TAD) internal audio connector.
All capture volumes (more than likely you want it high). It must also be picked as a capture device or no recording inputs go through at all.
I find that there are only 4-5 discrete gain levels available through this control -- if you have a recorder running (which displays signal levels -- gramofile works great) you can easily see the gain increments. For me, a level of 33 or 40 gives just the right amount of gain for a line-level input (with Line as the only capture device). Signals that top out the analog vu meter on my tape deck register ~90% volume on the digital recording.
When I have only Line set as a capture device, it records the line in only (as you would expect), but it also allows full-duplex operation. In this mode, I can mute the Line channel (so I don't hear the audio being recorded) and listen to the audio of my choice without interfering with the recording. The level of the Line channel seems to have absolutely no impact on record levels. This is a very handy feature when there are lots of tapes to digitize, and you're tired of listening to the material on them. :) (ALSA 0.9.0beta12 w/ SBLive! Value -- YMMV)
When selected as the capture device, all possible input devices are mixed together.
Same as 40 except stereo channels are combined and the result is put out in both speakers. (It makes the mixed signal mono.)
On my SB Live Value when I turn the AC97 level up past the Capture level I get a high pitched whine. It almost sounds like a digital version of analog feedback. Not very useful though, I keep it at 0.
On my SB Live Platinum original (no IR ports) this channel seems to have a strange function. With Mix, Capture, and a reasonable volume for LiveDrive line in, lowering the volume of this channel from 100% effectively lowers the maximum volume that the recording can attain which causes distortion. I recommend 100% volume on this channel.
This control isn't connected in most cards, and is used to turn on an "external amplifier" after the AC97 Codec chip. It's the equivalent of the SPK/LINE_OUT jumper on older sound cards. It's present in any card which uses an AC97 chip.
SB Live Analog/Digital Output Jack
This sets the output to either digital or analog for Gateway OEM cards, with only one output port. You must Mute it for analog output (for 5.1: center/subwoofer), not 0%.