One solution for configuring "Realtek ALC1200" in Alsa

Onboard sound for an Asus mobo, 'SB'/'HDA ATI SB (HDA-Intel - HDA ATI SB, HDA ATI SB) "Realtek ALC1200" chip.

Tools: alsamixer and amixer. For me, alsamixer sufficed for getting playback, but initially it seemed to me I needed amixer to capture input. In my case, I am using line-in ('Line') as my input, not my mic. As can be seen from this screenshot showing playback in alsamixer, I have enabled Line (key: M) and pushed the volume into red (key: up arrow). Switching to view: Capture (Key: Tab) I also enabled Capture (key: space). At this point I got stuck with alsamixer, because while I had playback, and could hear my input sound in my headphones, I could not record.

Thanks to a page by Maxim Levitsky and Paulo Roma Cavalcanti, I found out that there exists an actual control called 'Input Source' which toggles which input source is active. You can access those controls via amixer, cli only, or (as I realized later) via alsamixer as well. In the the capture screenshot of alsamixer at the right, 'Input So' should read 'Input Source' [1]. You can change source with the up and down keys. See for amixer man amixer and amixer -h for the full story (a few interesting general commands are amixer info; amixer scontrols; amixer scontents).

localhost:~$ amixer sget 'Input Source'
Simple mixer control 'Input Source',0
  Capabilities: cenum
  Items: 'Mic' 'Front Mic' 'Line' 'CD'
  Item0: 'Mic'
localhost:~$ amixer sget 'Input Source',1
Simple mixer control 'Input Source',1
  Capabilities: cenum
  Items: 'Mic' 'Front Mic' 'Line' 'CD'
  Item0: 'Mic'

As can be seen above, input source was Mic, which was not want I wanted. Below are the commands I used to switch to Line (but as I said, you can manipulate this with the arrow keys in alsamixer as well):

localhost:~$ amixer -c 0 sset 'Input Source',0 'Line' 
localhost:~$ amixer -c 0 sset 'Input Source',1 'Line'

Used the command alsactl store as root to save this, done.

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1. My mind is rather literal and explained 'input so' as pointing to a *.so library like e.g. the plugins of xmms. Also, I failed to realize at first glance that this item could be manipulated through arrow keys. Yes, I am a typical rather dumb end user, nothing special here. :(

Sat Dec 25 08:47:08 CET 2010