As implemented on LaserDisc, dts Digital Surround employs dts Incorporated's [formerly Digital Theater Systems'] Corporation's "Zeta" lossy compression format to encode five full-range audio channels and one Low Frequency Effects channel at a data rate of approximately 1.25 million bits per second. The bitstream thus produced is then packed into the data structure defined for RedBook PCM audio. The dts signal must be passed out of the LaserDisc player by a direct digital connexion and decoded by appropriate hardware; attempts to play back dts as PCM may generate dangerous levels of noise. On PAL discs and CDV singles, if a dts track is present there can be no other audio.