Topline, Abbey Road's free iOS recording app, gives you three tracks to work with, on top of your own imported audio track, and is presented in a clean and simple interface.
The idea is that generally you either multi-track vocals over an imported track or add up to two further tracks of audio to your original file. It's very much a sketchpad rather than a mobile DAW, then, but that doesn't mean you can't produce slick recordings.
Here, Jack from Abbey Road talks you through the recording principles that will help you with both Topline itself and any basic recording tasks. For more info or to download and use Topline for free, head over to the iOS app store now.
