Record from mic

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In order to record from a device, the device's "capture" switch must be set. To do so, run alsamixer, select your microphone and press space. Something like...

   CAPTUR
   L    R

should appear. On some cards there is a separate "Capture" device, which must be set to capture as well (and be unmuted, and have volume increased).

There can also be a "Mic Capture" volume that must be set. To avoid the sound from the microphone going through speakers, you can mute the microphone by pressing "m" (I am not sure about that.) Also keep your eyes open for a "Mic Boost" option. This may have only two settings, "muted" and "unmuted"; in the later case it will amplify the microphone input by an additional 20dB.

Another option to check is the Mic number. I battled for ages trying to get my mic working under SuSe 9.1. In the end I discovered I had to select "Mic 2" using alsamixer - the default was "Mic 1". Alternatively, run amixer to see all controls. An example of a part of the output can be:

Simple mixer control 'Mic',0
  Capabilities: pvolume pvolume-joined cvolume \
     pswitch pswitch-joined cswitch cswitch-joined
  Playback channels: Mono
  Capture channels: Mono
  Limits: Playback 0 - 31 Capture 0 - 7
  Mono: Playback 23 [74%] [on] Capture 5 [71%] [off] 

In this case you set Capture on with the command amixer sset Mic Capture cap. (The Capture volume was set with the command amixer sset Mic Capture 71%.) If you don't want the input from your microphone to go immediately through your speakers, mute the Playback: amixer sset Mic Playback mute. (I'm not very sure about that, correct me if I am wrong.)

I am also not sure the control you need to change is called 'Mic', in some cases, this can probably be another control or have another name.

Important: Make sure _both_ the Mic Capture and the Capture device are enabled (press space on them) and have a non-zero input volume. In alsamixer for my sound card, the Capture device (Item) is on the far right.

On many AC97 based soundcards Capture can have volume of 0 (thes means 0 dB). Max value is +34 dB. Capture control amplify input signal.

Other things to try:

Retrieved from "http://alsa.opensrc.org/Record_from_mic"

Category: Howto

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