[Alsa-user] i810: Recording from Line also captures Surround

[Fraser H. <ha...@te...>]

My new computer uses the intel i810 sound chip built into the 
motherboard.  I have a set of 3 speakers plugged into the front output 
jack (controlled by the "Master" channel), and a cheaper 2 speaker set 
plugged into the rear output jack (controlled by the "Master Surrond" 
channel).  I have a radio plugged into the computer's Line In jack (the 
"Line" channel.)

I wrote some scripts to record radio programs from the Line channel at 
certain times.  I usually keep the Line channel muted.  I can record my 
radio programs from the muted Line channel just fine.  The only trouble 
is, if I happen to be playing music with XMMS (on the PCM channel, with 
the alsa output plugin) while I record from Line, then the recording 
includes both what's coming in off the Line channel AND whatever is 
going out on the "Master Surround" channel.

I really enjoy my low-budget surround-sound setup, and I don't want to 
make my radio recording script disable surround sound whenever I am 
recording from Line In.  Can anyone suggest how I can record from Line 
In without interference from Master Surround?

--Fraser


ps. amixer output:

Simple mixer control 'Master',0
   Capabilities: pvolume pswitch
   Playback channels: Front Left - Front Right
   Limits: Playback 0 - 31
   Front Left: Playback 25 [81%] [on]
   Front Right: Playback 25 [81%] [on]
Simple mixer control 'Master Mono',0
   Capabilities: pvolume pvolume-joined pswitch pswitch-joined
   Playback channels: Mono
   Limits: Playback 0 - 31
   Mono: Playback 0 [0%] [on]
Simple mixer control 'Master Surround',0
   Capabilities: pvolume pswitch
   Playback channels: Front Left - Front Right
   Limits: Playback 0 - 31
   Front Left: Playback 26 [84%] [on]
   Front Right: Playback 26 [84%] [on]
Simple mixer control 'PCM',0
   Capabilities: pvolume pswitch
   Playback channels: Front Left - Front Right
   Limits: Playback 0 - 31
   Front Left: Playback 16 [52%] [on]
   Front Right: Playback 16 [52%] [on]
Simple mixer control 'Surround',0
   Capabilities: pvolume pswitch
   Playback channels: Front Left - Front Right
   Limits: Playback 0 - 31
   Front Left: Playback 0 [0%] [on]
   Front Right: Playback 0 [0%] [on]
Simple mixer control 'Surround Jack as Input',0
   Capabilities: pswitch pswitch-joined
   Playback channels: Mono
   Mono: Playback [off]
Simple mixer control 'Center',0
   Capabilities: pvolume pvolume-joined pswitch pswitch-joined
   Playback channels: Mono
   Limits: Playback 0 - 31
   Mono: Playback 0 [0%] [on]
Simple mixer control 'Center/LFE Jack as Input',0
   Capabilities: pswitch pswitch-joined
   Playback channels: Mono
   Mono: Playback [on]
Simple mixer control 'LFE',0
   Capabilities: pvolume pvolume-joined pswitch pswitch-joined
   Playback channels: Mono
   Limits: Playback 0 - 31
   Mono: Playback 0 [0%] [on]
Simple mixer control 'Line',0
   Capabilities: pvolume pswitch cswitch cswitch-joined cswitch-exclusive
   Capture exclusive group: 0
   Playback channels: Front Left - Front Right
   Capture channels: Front Left - Front Right
   Limits: Playback 0 - 31
   Front Left: Playback 24 [77%] [off] Capture [on]
   Front Right: Playback 24 [77%] [off] Capture [on]
Simple mixer control 'CD',0
   Capabilities: pvolume pswitch cswitch cswitch-joined cswitch-exclusive
   Capture exclusive group: 0
   Playback channels: Front Left - Front Right
   Capture channels: Front Left - Front Right
   Limits: Playback 0 - 31
   Front Left: Playback 25 [81%] [on] Capture [off]
   Front Right: Playback 25 [81%] [on] Capture [off]
Simple mixer control 'Mic',0
   Capabilities: pvolume pvolume-joined pswitch pswitch-joined cswitch 
cswitch-joined cswitch-exclusive
   Capture exclusive group: 0
   Playback channels: Mono
   Capture channels: Front Left - Front Right
   Limits: Playback 0 - 31
   Mono: Playback 0 [0%] [on]
   Front Left: Capture [off]
   Front Right: Capture [off]
Simple mixer control 'Mic Boost (+20dB)',0
   Capabilities: pswitch pswitch-joined
   Playback channels: Mono
   Mono: Playback [on]
Simple mixer control 'Mic Select',0
   Capabilities:
   Mono:
Simple mixer control 'Video',0
   Capabilities: cswitch cswitch-joined cswitch-exclusive
   Capture exclusive group: 0
   Capture channels: Front Left - Front Right
   Front Left: Capture [off]
   Front Right: Capture [off]
Simple mixer control 'Phone',0
   Capabilities: pvolume pvolume-joined pswitch pswitch-joined cswitch 
cswitch-joined cswitch-exclusive
   Capture exclusive group: 0
   Playback channels: Mono
   Capture channels: Front Left - Front Right
   Limits: Playback 0 - 31
   Mono: Playback 0 [0%] [on]
   Front Left: Capture [off]
   Front Right: Capture [off]
Simple mixer control 'Aux',0
   Capabilities: pvolume pswitch cswitch cswitch-joined cswitch-exclusive
   Capture exclusive group: 0
   Playback channels: Front Left - Front Right
   Capture channels: Front Left - Front Right
   Limits: Playback 0 - 31
   Front Left: Playback 0 [0%] [on] Capture [off]
   Front Right: Playback 0 [0%] [on] Capture [off]
Simple mixer control 'Capture',0
   Capabilities: cvolume cswitch
   Capture channels: Front Left - Front Right
   Limits: Capture 0 - 15
   Front Left: Capture 9 [60%] [on]
   Front Right: Capture 9 [60%] [on]
Simple mixer control 'Mix',0
   Capabilities: cswitch cswitch-joined cswitch-exclusive
   Capture exclusive group: 0
   Capture channels: Front Left - Front Right
   Front Left: Capture [off]
   Front Right: Capture [off]
Simple mixer control 'Mix Mono',0
   Capabilities: cswitch cswitch-joined cswitch-exclusive
   Capture exclusive group: 0
   Capture channels: Front Left - Front Right
   Front Left: Capture [off]
   Front Right: Capture [off]
Simple mixer control 'Downmix',0
   Capabilities:
   Mono:
Simple mixer control 'Exchange Front/Surround',0
   Capabilities: pswitch pswitch-joined
   Playback channels: Mono
   Mono: Playback [on]
Simple mixer control 'External Amplifier',0
   Capabilities: pswitch pswitch-joined
   Playback channels: Mono
   Mono: Playback [on]
Simple mixer control 'Spread Front to Surround and Center/LFE',0
   Capabilities: pswitch pswitch-joined
   Playback channels: Mono
   Mono: Playback [on]
Simple mixer control 'Stereo Mic',0
   Capabilities: pswitch pswitch-joined
   Playback channels: Mono
   Mono: Playback [on]