"DVD-Audio offers at least 74 minutes of very high quality, surround sound, plus additional features (such as video and limited interactivity) that are not available on CDs. Capacity of a single layer DVD-Audio is of high quality full surround sound audio. In addition the disc can accommodate the same audio encoded as Dolby Digital for playing on existing DVD-Video players. In early 2004 the major music companies carried out a limited trial launch of a double-sided version with a CD compatible layer to play on DVD and CD players. These discs are called Dual Discs, but another name is DVDPlus."