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mecha_streisand

Member

Registered: 2014-08-03

Posts: 2

[SOLVED] External Mic in alsa

Hi everyone,

I want to record something from an external audio source via line in through the mic in of my computer. However, whenever I plug the line in to the mic-port, it switches automatically to the internal microphone and thus I cannot record.

I have a Thinkpad T430 that uses a headphone/mic combo-jack and I bought a splitter cable for it.
I've tried the setup with external headsets (with a real microphone plugged into the mic in, not a line-in) and there it works fine, it records from my external mic.

I read in other forums, that this automatic switching might be due to the impedance difference ( https://forums.lenovo.com/t5/T400-T500- … 613/page/3 )

The werid thing however is, that in my alsamixer view in the playback section there is a field named "mic" that allows me to playback the external input, even for line-in signals. So although it switches to the internal microphone automatically, the external input still somehow processed by the system, I just can't record from it.

My question now is if there is some possibliity to tell alsa explicilty which microphone to use for capturing. I could not find any option for this in the alsamixer view.
I also thought about the possiblity of a playback loop, but I would like to avoid that as I might want to output other audio while recording only the line in.

Thank you for your help!

Last edited by mecha_streisand (2014-08-03 11:18:05)

dice

Member

From: Germany

Registered: 2014-02-10

Posts: 413

Re: [SOLVED] External Mic in alsa

Which program are you using to record? Are you using pulseaudio?

The werid thing however is, that in my alsamixer view in the playback section there is a field named "mic" that allows me to playback the external input, even for line-in signals.

So the input from your external plugged in mic is played on your speakers correctly.
Does this

arecord -d 20 test.wav

work too?

---

I put at button on it. Yes. I wish to press it, but I'm not sure what will happen if I do.  (Gune | Titan A.E.)

emeres

Member

Registered: 2013-10-08

Posts: 1,570

Re: [SOLVED] External Mic in alsa

There usually is a socket called line-in and mic. Do I understand it correctly that you want to record output from somewhere else using a jack plugged into the headphone/mic socket?
If so, for that you could also use hdajackretask from alsa-tools to set that jack socket as microphone. There are threads about listening what is recorded via software and 'hardware' loop[back]. Try using arecord on the specified hardware or dsnoop, read 'man arecord'. I guess this socket has 4 pins, does that headphone/mic combo-jack have 4 pins?

Edit: Too slow, my bad.

Last edited by emeres (2014-08-03 10:35:08)

mecha_streisand

Member

Registered: 2014-08-03

Posts: 2

Re: [SOLVED] External Mic in alsa

Thanks a lot for the quick help.

emeres suggestion of using hdajackretask did the trick.
I retasked the mic jack from microphone to line in and that made it work. Now i can finally  record line in to my laptop.
Thank you again

emeres

Member

Registered: 2013-10-08

Posts: 1,570

Re: [SOLVED] External Mic in alsa

You are welcome.