Microphone Input Solution

[jjalocha]

This is my experience with microphone input problems, and how I solved them. Many people are having different problems with microphone input in Ubuntu, so I hope this post is helpful for some of them.

Both, with Edgy and Feisty, my hardware gets detected correctly out of the box, but I was unable to record anything, using a microphone plugged into the jack.

This is my soundcard:

$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: SB [HDA ATI SB], device 0: STAC92xx Analog [STAC92xx Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

lspci gives different output in Edgy and Feisty:

Edgy:

$ lspci
[...]
00:14.2 Audio device: ATI Technologies Inc Unknown device 4383
[...]

Feisty:

$ lspci
[...]
00:14.2 Audio device: ATI Technologies Inc SB600 Azalia
[...]

The solution needs the alsamixer and amixer command line tools. If they aren't installed already, you need to install the 'alsa-utils' package (using for example Synaptic).

From the command line, you can use alsamixer. Use TAB for selecting the 'Playback', 'Capture' or 'All' window, and use LEFT/RIGHT to select the desired control. You have to make sure you get the following settings right (all of them):

• All channels must be non-zero (use UP/DOWN).
• 'Capture' must be enabled (use SPACE).
• Select the correct 'Input Source' if you have more than one. (I only have 'Mic'.)

In my case, i had to enable 'Capture'. This is how it looked before the change (not-working). Note dashed line above 'Capture':



And this is how it looked after getting it right. Note red 'CAPTUR' tag above 'Capture':



Activating capture can be done easier with the amixer tool:

$ amixer set 'Capture' cap

If the configuration gets lost after each reboot, then you can make the cnahge permanent adding this line to '/etc/rc.local' file, before 'exit 0'.

Simply typing amixer in the terminal puts out your current settings. In my case, when 'Capture' was disabled, both channels were '[off]':

Simple mixer control 'Capture',0
  Capabilities: cvolume cswitch
  Capture channels: Front Left - Front Right
  Limits: Capture 0 - 15
  Front Left: Capture 9 [60%] [13.50dB] [off]
  Front Right: Capture 9 [60%] [13.50dB] [off]

After enabling it:

Simple mixer control 'Capture',0
  Capabilities: cvolume cswitch
  Capture channels: Front Left - Front Right
  Limits: Capture 0 - 15
  Front Left: Capture 9 [60%] [13.50dB] [on]
  Front Right: Capture 9 [60%] [13.50dB] [on]

[2007-04-22 EDIT: Added /etc/rc.local fix.]
[2007-04-23 EDIT: Better explained.]