I am trying to duplicate my Line In over USB Sound Card.

I have RPi 3 B+ and USB Sound Card with Line In.

Currently I have an application for stream over IP the Line In audio of USB sound card. Now I want to make a VU meter to observ sound level of input. I tried to use arecord or sox but I am getting source is busy error because my application uses the ALSA audio source. How can I duplicate it? Maybe create a virtual piped audio in that can alsa recognize ? Or another approach for it

1 Answer 1


After days of search I found dsnoop way working: Dave answer

But it has to be changed according to your device. for me it is "hw:1,0"

  • Please accept your own answer with a click on the tick on its left side. Only this will finish the question and it will not pop up again months for months.
    – Ingo
    Dec 15, 2019 at 1:14

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

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