SACDs present higher audio fidelity through the use of a propietary format which offers a maximum bitrate up to 64 times higher than that of standard CDs. Though SACD releases can only be played in special SACD players, discs that are labeled "SACD Hybrid" include an additional CD layer of audio that can be played back on standard CD players (though quality is limited to CD quality through standard CD player playback). SACD releases can contain either or both stereo and 5.1 channel mixes.