usb - Why is this sound device recognized but no software can record with it?

24
2014-04
  • Dave M G

    I recently bought an Alesis iO4, a 4 microphone USB input device, which, according to this site works under Linux "completely", and was tested using Ubuntu 9.04. So I thought it was a good bet it would work with my 12.10 Ubuntu laptop.

    When I connect it by USB to my laptop, it is recognized under the sound settings, and if I speak into the microphones I can see a response:

    sound input

    So far so good. However, in Audacity, when I press "record", I see no response whatsoever. My main concern is Audacity, but I tried also using Ubuntu's "Sound Recorder" utility, and it also showed no response in its level meter when I spoke into the mike, so I think this isn't just an Audacity problem.

    I looked into Audacity's preferences, and under Host in the Interface section, the only option is ALSA. Under Device in the Recording section, there are four options. HDA:Intel is my on-board sound card. I'm not sure what the difference between pulse, default, and sysdefault is, but in any case, selecting any of them does not seem to change anything.

    audacity settings

    Why is my sound device seen by the OS but not by Audacity (or any other software)?

    How do I set it up so that Audacity takes input from this device?


    Update: According to a very helpful person on the Audacity forums, the problem I'm reporting here is most likely caused by a bug in ALSA. The current version of ALSA in the Ubuntu repositories does not seem to contain the necessary patch, so I'm hoping it will be updated soon.

  • Answers
  • rockon999

    It is an issue with Audacity getting your mic's input.. I had the same issue with Teamspeak and still do with Skype. Basically you need to play around with the host, and usually under Recording using the default device works. :)

  • Dave M G

    Thanks to very helpful advice on the Audacity forums, and also a little lucky experimentation, I have discovered a workable solution.

    The key is that the iO4 must be plugged in before the laptop boots. If I try to plug it in any other time after that, it does not work as described in the question. If I plug it in before booting, then it's very easy. Audacity can select the device independentaly of any other sound settings and will record all four channels.

    I believe this might be a bug in that a USB device should be able to work even when plugging in after booting the computer (all my other USB devices work this way). But I will file a bug report for that. For the time being, I can at least use my device as intended, so the issue as originally outlined can be considered closed.

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  • Related Question

    sound - USB Audio Device Loopback Through Speakers
  • matto1990

    I have a USB turntable which when plugged in to my ubuntu 10.10 machine appears in the audio settings as an input device (USB PnP Audio Device Analog Stereo) like a microphone.

    What I'd like to be able to do it to have the sound for that audio device played back through the audio output (speaker or whatever). I'm not too worried if there's a slight delay between the audio coming in and it being played out through the speakers.

    As far as I'm aware this is refereed to as software loopback. I can achieve exactly what I want if I open Audacity, enable software loopback and press record. Obvious this isn't ideal as I don't really want it recording what I'm playing all the time.

    I know this is possible because of the Audacity example however I'd like to know if there's a way to do it without it recording. I've search around for a while for a piece of software that does this, however I couldn't get anything even close.

    Any help would be greatly appreciated.


  • Related Answers
  • Clausi

    Just a warning: This answer is theoretical, because i don't own such hardware...

    AFAIK you have to enable a loopback-device for pulseaudio:

    pactl load-module module-loopback
    

    After that you should see a new application under audio-settings.

    If it works well, you may add a line to the pulse-audio-config to make this persistent:

    sudo sh -c ' echo "load-module module-loopback" >>  /etc/pulse/default.pa '
    

    Good luck!

    Additional info from matto1990:

    You only need to do this if you want to loopback from a device other than the microphone or line in (the default ones). Go to software center and install "PulseAudio Volume Control". Open it up and go to the recording tab. In the show dropdown select "all". In the "loopback from internal audio" section (or whatever the output device you want is) select the input device you want to loopback from (in my case the USB one).