I need mono sound from ALSA (not stereo)
  • Vote Up0Vote Down Marcus GregoryMarcus Gregory
    Posts: 6Member
    Hi,

    Is there an easy way to change to sound output from Airtime via ALSA from stereo to mono?

    I am setting Airtime up for a community radio station, their stereo encoder for FM is not currently working so I want to be able to plug the Left (or Right) XLR output from my audio interface directly into the transmitter as a temporary solution while the stereo encoder is sorted out. Of course I can do this now but I'll only be transmitting the left or right channel.

    I've tried doing this by changing "asound.conf" but when I change this Airtime will not use ALSA.

    Has anybody done this?

    Thanks

    Marcus
  • 3 Comments sorted by
  • Vote Up0Vote Down Voisses TechVoisses Tech
    Posts: 1,423Member
    Try buy a XLR to RCA  or XLR to 1/4

    Hope that work

    Good Luck
    VOISSES
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  • Vote Up0Vote Down Lucas BickelLucas Bickel
    Posts: 8Member
    Have you tried setting up something similar to the virtual multi channel devices example from the alsa docs using only one soundcard and replacing pcm.multi with pcm.!default.
    You should be able to configure the downmix to mono like in this 5.1 to stereo example by tweaking pcm.ttable.

    AFAIK airtime-liquidsoap honors redefining the default alsa device in such a fashion.

    Lucas
    Post edited by Lucas Bickel at 2014-04-29 18:43:36
  • Vote Up0Vote Down Marcus GregoryMarcus Gregory
    Posts: 6Member
    I tried pcm.ttable etc but in the airtime liquidsoap log it just said 'ALSA:Invalid arguments'.

    My solution for now is to set up another stream, MP3, mono with max bit rate pointing at the local machine. Then use Mplayer to pick that up and send it to my USB Audio interface. I also set up a script that runs every minute to checks Mplayer is running and restart if necessary.

    Works for now...

    Thanks for your help.

    Marcus
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