Recording will default to a mono track but you can control all that with this pop up menu when you create a new track. When you click on details, this drop down menu appears. Here you can choose to record with input 1 or input 2, which is your left and right microphone/speaker. You can choose to record with input 1 + 2 for a stereo recording track. This also allows you to pick your recording devices easily and switch devices between tracks, as well as to hear your instrument through GarageBand as you play and record.
The top is a mono track and the bottom is a stereo track.
A mono track is single channel audio, while a stereo track is dual channel audio. Most speaker systems are stereophonic, meaning there are two of them, one for left and right. A mono track will either reproduce the channel so that the left and right channels are playing the same, homogenized recording, or will play through only one of the left or right channels. A stereo track then is audio that recorded two often similar but different recordings that were recorded in two channels, one left, one right. Wav recorders usually have the option of recording in mono or stereo while certain microphones are specifically mono or stereo. Oftentimes, mono recordings will automatically convert to stereo in playback through stereo speakers.
The gain/volume slider should not reach above 0 or turn red because that means the levels are too high and are probably going to clip.
You can easily import audio files, MIDI, and raw data into your timeline. There is even a keyboard shortcut for importing audio files. You can also click and drag an audio file straight into GarageBand.
The media browser makes it possible to access audio and video files and easily drag them into your timeline.
You can also upload a video and edit to it, as well as exporting the audio to the video file when you are done.
