Creative Sound Blaster Live 24-bit external (USB)

= About =

Using the SB Live USB box under gentoo. (Note: no Creative USB card will give you proper surround sound (except when doing HW AC3 decoding). If you want a decent surround USB soundcard, better check out Terratec's Aureon, works flawlessly under Linux.)

= Installation =

Edit your /etc/make.conf and add the USB Sound Card or it will not compile support for all the ALSA drivers (this saves a lot of time and headaches down the road).

So now let's emerge alsa:

nano /etc/modprobe.d/alsa

= Configuration =

Let's edit alsa configuration file:

after this update modules like so:

Getting alsa to play multiple streams
All of Creative Labs External USB cards use the same driver in Linux, which is snd-usb-audio. Earlier, I mentioned putting a line of code in your /etc/make.conf to have ALSA installed for your specific sound card. If you did that, then this part is super simple.

There are two ways to configure ALSA. You can either configure it on a global level, or on a local level. If you wanted to have the sound work for certain users, you would put everything in the box below in your ~ directory (normally /home/USERNAME/.asoundrc), but I'm going to show you how to configure it globally.

Just copy and paste what is in the box below to a new file named /etc/asound.conf

then make update-modules and env-update.

Since you have that !default item in that file, you don't need to worry about changing the Audio Device configuration in your audio programs.

Surround Sound for Extigy (4, 5, 6 channel playback; ie. DVD playback)
To play a DVD in surround using your Extigy, ALSA, and MPlayer, MPlayer has a flag "-ac hwac3" to allow the surround encoding on a DVD to be sent to your extigy. For other applications you will have to find how they support sending AC3 to hardware, but most likely it won't be much different. You have to ensure that MPlayer attempts to use your third subdevice of the Extigy. That means if your Extigy is accessed by "hw:1" for normal playback, then you need to get MPlayer to use "hw:1,2" (ie. "mplayer dvd://1 -ao alsa:device=hw=1,2"). Then in alsamixer you have to set the "channel" control to the appropriate setting for your surround configuration. Only the exaudio driver for OSS mentioned this by the following:

The extigy has seven speaker modes when decoding AC3 audio:

Channel names:

Rs = Right surround, Ls = Left surround,

LFE = Low frequency enhancement, C = Center front,

R = Right front, L = Left front

For my configuration of 2 front and 2 rear speakers, I use mode 4. However, a further peculiarity is that the names of the channels as reported by amixer are incorrect, at least in my case. Amixer reports the following: Simple mixer control 'Master',0 Capabilities: pvolume pswitch pswitch-joined Playback channels: Front Left - Front Right - Rear Left - Rear Right - Front Center - Woofer Limits: Playback 0 - 200 Mono: Front Left: Playback 180 [90%] [on] Front Right: Playback 180 [90%] [on] Rear Left: Playback 0 [0%] [on] Rear Right: Playback 0 [0%] [on] Front Center: Playback 200 [100%] [on] Woofer: Playback 200 [100%] [on]

However, the reported rear left actually is the front center, the rear right is the woofer, the front center is the rear left and the woofer is the rear right. This had me pretty confused for a while. So, in alsamixer the first stereo Master is front, second stero Master is center & woofer, third mono Master is rear left, and fourth mono is rear right.

When using surround using the fifth mono Master controls the volume of all channels, but a quirky thing about it is it changes all the channels to its volume as opposed to increasing or decreasing them relative to their prior value.

Edited by: holms