# Channel Mapping

Audio devices usually have two or more channels, each of which can carry distinct audio. For example, a stereo microphone has both left and right channels. By default, Loopback handles channel mapping automatically, as detailed on the Audio Sources page. However, if you know you need a custom setup for your virtual audio device, you can modify the channel mapping as needed.

### Manually Configuring the Channel Mapping

After you've added your desired sources to the Audio Sources table, you can manually configure the virtual audio device's channel mapping. To begin, toggle the Channel Mapping setting to “Manual”. When you do, the Channel Mapping table will appear, as will the Channels column in the Audio Sources table.

The Channel Mapping Table

By default, virtual audio devices have two channels, but they can be configured to offer anywhere from 1 to 32 channels. To add or remove channels, just use the +/- controls at the bottom of the Channel Mapping table.

Once you've got your desired number of channels set, you can drag and drop individual channels from the Audio Sources table down to the Channel Mappings table. Below, you can see that channels from QuickTime Player, iTunes, and the USB mic have been added to the device.

The Channel Mapping Table, Configured

In this setup, the physical microphone's audio will be heard on channels one and two of the virtual audio device, while QuickTime Player and iTunes will be heard on the third and fourth channels. Custom setups like this make it easy to record audio to distinct tracks, just based on the channels selected in your recording application.

With that set, the device is now ready for use! Here's our fully configured device:

A Fully Configured Loopback Device