MediaTrackSettings: channelCount property

The MediaTrackSettings dictionary's channelCount property is an integer indicating how many audio channels the MediaStreamTrack is currently configured to have. This lets you determine what value was selected to comply with your specified constraints for this property's value as described in the MediaTrackConstraints.channelCount property you provided when calling either getUserMedia() or MediaStreamTrack.applyConstraints().

If needed, you can determine whether or not this constraint is supported by checking the value of MediaTrackSupportedConstraints.channelCount as returned by a call to MediaDevices.getSupportedConstraints(). However, typically this is unnecessary since browsers will ignore any constraints they're unfamiliar with.