DTS (Digital Theater Systems inc) is the direct competitor of Dolby Digital. Like Dolby, it is a digital data compression system applied to a high quality 5.1 sound channel. Some people think it gives better quality than Dolby Digital, thanks to a lower compression ratio that is truer to the original sound. Some music disks have been recorded on CD using this process. With the constant progress of Dolby Digital and DTS, it is not always easy to differentiate the two systems, and one could be preferred to the other according to the preferences of the sound engineers who did the original mixing.