SDDS: Sony Dynamic Digital Sound. Developed by Sony, SDDS is a digital film surround-sound format comprising the SDDS soundtrack, optically printed on both edges of 35mm film, and SDDS playback hardware. The SDDS split-surround format uses the usual 5.1 stems, plus additional left-center and right-center channels. The additional two speakers are employed at the front of the soundstage to deliver more uniform sound in wide-format theaters of screen widths of up to 60 inches or more. An important aspect of the SDDS format is that it can be decoded into four, six, or eight channels for playback on a wide variety of audio systems. Proponents of this format claim that the extra front channels make a significant difference in the amount of depth, fullness and natural image of the audio.