1

I want to play a metronome audio tick out of the built-in headphone port, while playing an audio stream out of a USB soundcard. How can I do this?


Deeper context:

JACK is running the USB soundcard, and Pulseaudio is probably the thing that is in charge of the built-in soundcard*.

My first thought is to use both JACK and Pulseaudio in tandem, using the JACK sink for pulseaudio input. Routing the metronome to the Pulseaudio JACK source makes the JACK source appear in pavucontrol under the 'Input Devices' tab - the mixer shows it is receiving the metronome signal. But not matter what I can do I can't get this to actually be output by pulseaudio at any point.

How can I send the signal from JACK source to the built-in headphone port while still using the USB soundcard?


(* Tested this by using the 'Test Sound' function in Linux Mint's Sound manager - plays a test tone happily out of the headphones, which suggests this should be possible!)

  • You don't seem to be running Pulseaudio at all (you can check with ps axu) I suggest to remove the pulseaudio tag. – dirkt Mar 20 '17 at 13:33
  • Good point - though originally I thought that it was a pulseaudio problem. Better to leave it in to be helpful to people in a similar situation or remove it for correctness? – avidreader610 Mar 25 '17 at 23:12
2

Fixed it!

Solution: using the alsa_out module.

To use them, you start JACK as normal. Then you start an instance of alsa_in or alsa_out for each additional device (and “direction”) that you want to use. alsa_out will create a set of ports representing the playback capabilities of the device, and alsa_in will represent the capture/recording capabilities

So:

  1. arecord --list-devices to find name of built-in soundcard (hw:0,0)
  2. alsa_out -d hw:0,0 to create the alsa_out ports that now appear in jack
  3. Connect up metronome to alsa_out port in JACK - now plays metronome out of headphone socket and any other audio desired out of USB soundcard!

http://www.jackaudio.org/faq/multiple_devices.html

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.