A computer implemented method for providing audio contents as a plurality of tracks to be played on a listener's mobile client device with Internet radio capabilities, the client device intended to be connected to the Internet. The method comprises: obtaining, as a listener's input into the listener's client device, a playlist definition; selecting, from a plurality of tracks, tracks meeting the playlist definition to form a playlist, wherein the playlist is formed by playlist entries that include track identifications referring to selected ones of the plurality of tracks. The plurality of tracks comprises (i) tracks present in a remote master media inventory, tracks present in an Internet-based cloud memory environment, and-or tracks present in a local media content inventory of the listener's client device; a hybrid engine software library generates personalised track playlists for a listener based on details of the listener's input, a current configuration of the system, the plurality of tracks, and current network conditions.