Cinema Digital Sound

Cinema Digital Sound (CDS) was a multi-channel surround sound format used for theatrical films in the early 1990s. The system was developed by Eastman Kodak and Optical Radiation Corporation. CDS was quickly superseded by Digital Theatre Systems (DTS) and Dolby Digital formats.

CDS replaced the analogue audio tracks on 35 mm and 70 mm film prints with 5.1 discrete audio. The 5.1 tracks were encoded using 16-bit PCM audio in a delta modulation compression which resulted in a compression level of 4:1. The audio channels in CDS were arranged in the same way that most current 5.1 systems with Left, Center, Right, Left Surround, Right Surround and LFE. Dick Tracy (1990) was the first film encoded with CDS. Not all films with CDS soundtracks used all 5.1 channels; some, such as Edward Scissorhands (1990), used only the 4 channels that were supported by Dolby Stereo. Universal Soldier (1992) was the last film encoded with CDS.

The digital information was printed on the film, similar to Dolby Digital and SDDS. However, unlike those formats, there was no analog optical backup in 35 mm and no magnetic backup in 70 mm, meaning that if the digital information were damaged in some way, there would be no sound at all. This was one of the factors that contributed to its inevitable demise; the then-new Dolby Digital format moved its information to another area (in between the film sprocket holes), preserving the optical tracks.