Sound Blaster Extigy (Howto)

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This article describes how to get the Sound Blaster Extigy/Audigy working with ALSA.

How do I use LIRC's alsa_usb plugin for my SB Extigy/Audigy remote control?

Support for the remote controls of SB Extigy/Audigy is added in version 1.0.9 of the alsa-drivers, the alsa_usb module is in lirc version 0.7.2. LIRC's alsa_usb module relies on the alsa device names. /proc/asound/cards lists the number and name of each recognized soundcard:

   0 [Extigy       ]: USB-Audio - Sound Blaster Extigy
                      Creative Technology Ltd. Sound Blaster Extigy at usb-0000:00:1d.1-2, full speed
   1 [I82801DBICH4 ]: ICH4 - Intel 82801DB-ICH4
                      Intel 82801DB-ICH4 with AD1981B at 0x24000800, irq 11
   2 [Modem        ]: ICH-MODEM - Intel 82801DB-ICH4 Modem
                      Intel 82801DB-ICH4 Modem at 0x1400, irq 11

You can either pass the number or name of the sound card prefixed with hw: to lircd. In this case lircd -d hw:0 or lircd -d hw:Extigy. I recommend using the name, since it is independent of the order in which the devices are discovered and lircd will exit, if the Extigy is not connected.


How do I get AC3 surround sound with my Sound Blaster Extigy?

In order to play a DVD with surround sound using your Extigy, you need to access the third device on the card. So if you usually access your Extigy as hw:1 then the third device on the card is hw:1,2, or if you want to use names hw:Extigy,2. This device accepts an SPDIF formatted AC3 stream which your video player passes to the card. Both xine and mplayer can do this.

Xine: You need to set the passthrough device (device.alsa_passthrough_device) to this device (hw:Extigy,2) and set the speaker arrangement (output.speaker_arrangement) to "Pass Through". N.B. in kaffeine device.alsa_passthrough_device and device.alsa_surround51_device share the same description "device used for 5.1-channel output" so make sure you get the right one.

MPlayer: The flag "-ac hwac3" instructs mplayer to send the encoded stream directly to your soundcard. Ensure that mplayer uses the third device either through a configuration file or at the command line (e.g. playing a dvd: "mplayer dvd://1 -ac hwac3 -ao alsa:device=hw=Extigy.2")

Now, whenever you play a video with an AC3 audio track (such as a dvd), the Digital LED will light up and you get surround sound.

Finally you need to adjust the output of the Extigy to your surround sound setup. In alsamixer you can do this by adjusting the "channel routing mode" control to the appropriate setting for your surround configuration. The exaudio driver for OSS mentioned this by the following:

The extigy has seven speaker modes when decoding AC3 audio:

mode  Rs Ls LFE C  R  L
  1   0  0   0  0  1  1
  2   0  0   0  0  1  1
  3   0  0   1  0  1  1
  4   1  1   0  0  1  1
  5   1  1   1  0  1  1
  6   1  1   0  1  1  1
  7   1  1   1  1  1  1
Channel names: 
 Rs = Right surround, Ls = Left surround,  
 LFE = Low frequency enhancement, C = Center front, 
 R = Right front, L = Left front 

\ In alsamixer, 1 corresponds to 00 and 7 to 100 with the rest spaced evenly in between. For a configuration of 2 front and 2 rear speakers, use mode 4. However, a further peculiarity is that the names of the channels as reported by amixer are incorrect, at least in one 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
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 channels do not match the ones that they control (this has been reported as a bug). The mapping is like this:

control:     speaker:
front left   front left
front right  front right
rear left    front center
rear right   woofer
front center rear left
woofer       rear right

In alsamixer you control front and rear with the first two stereo mixers which then gives you front left + right on the first mixer and center and woofer on the second stereo mixer. The other two mono mixers intended for center and woofer give you rear left and rear right.

Additionally there is another mono mixer in alsamixer called Master 1. This mixer controls all channels. Unfortunately it does not increase or decrease them relative to each other but sets them to one fixed value.

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Category: Howto