SVA

SVA (Stereo Variable Area) is a type of analog variable area optical sound track that is recorded and played back in stereo. It is always a dual bilateral track and is always encoded either as Dolby® A, Dolby SR or Ultra Stereo™.

The frequency response of SVA tracks is between 31Hz to 12.5kHz. All SVA opticals are encoded as Lt/Rt, giving some omni-directional surround information for theatrical playback. The format, introduced in the late 1970s, was used widely throughout the 1980s, but was replaced by multi-channel digital formats (Dolby SR-D, DTS and SDDS) in the 1990s. It is still utilized by very small theaters that have not upgraded to digital cinema processors and as a backup track (in the event that a film's digital tracks degrade or fail during playback) in all theaters.

The only playback problems encountered with SVA tracks are those associated with basic wear and tear, i.e., crackles, pops, skips, and upcut audio resulting from scratching or breakage. As with all analog optical film tracks, the original fidelity of an SVA track will not degrade. Stored properly, optical film will last well over 100 years. In terms of longevity, optical film is still the best media for the storage of sound.