---
name: "alsa_loopback"
section: "1"
platform: "linux"
package: "zita-alsa-pcmi-utils"
version: "0.6.1-1.1+b1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/alsa_loopback"
---

# alsa\_loopback(1)

loop back the first two channels of a alsa device to another device

## NAME

alsa\_loopback - loop back the first two channels of a alsa device to another device

## SYNOPSIS

**alsa\_loopback** playdev captdev fsamp frsize nfrags

## DESCRIPTION

This tool is mainly for testing whether a given soundcard works with the **zita-alsa-pcmi** library. It will send the 1st two channels of the given capture device to the playback device, using the specified settings.

Note, that this might give massive (ear and equipment damaging) feedback if your capture device is connected to a microphone near some speakers connected to the playback device.

## ARGUMENTS

- **playdev**

  ALSA playback device (e.g.: hw:0)

- **captdev**

  ALSA capture device (e.g.: hw:0)

- **fsamp**

  Sample rate (e.g.: 48000)

- **frsize**

  Period size (e.g.: 256)

- **nfrags**

  Number of fragments (e.g.: 2)

## EXAMPLES

This will loopback the 1st two channels of **hw:0** to  **hw:1** using 48kHz samplerate, and 10 fragments each 2048 samples.

```
  alsa_loopback hw:0 hw:1 48000 2048 10
```

## AUTHOR

zita-alsa-pcmi was written by Fons Adriaensen \<fons@linuxaudio.org\>.

This manual page was written by IOhannes m zmoelnig \<zmoelnig@iem.at\> for the Debian project (but may be used by others).