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SECTION 1
INTRODUCTION
1.1
Introduction
The Model SEU4 is used to generate Dolby Surround program material. The SEU4
contains a precision four-to-two spatial encoding network that is used to combine four
directionally allocated input signals (Left, Center, Right and Surround) into a two-channel
distribution pair. The two-channel output of the SEU4 contains the original four-channel
directional information in a matrix encoded form that allows subsequent decoding by
suitable consumer or professional decoding devices into four channel materials.
The SEU4 encoder is designed to be used in conjunction with the companion SDU4
Surround Decoder. Satisfactory generation of program material for surround encoding
requires mixing and monitoring using what is known as the “4-2-4” technique. A four-
channel mix is prepared and sent to the input of the SEU4 Surround Encoder via the
mixing console. The SEU4 generates a pair of channels that are recorded for subsequent
distribution. Simultaneously, the two-channel material is decoded using the SDU4 and
monitored in the mixing environment. This allows mixing engineers to adjust the mix
content in real time to fit the final playback environment. The 4-2-4 technique is essential
not only to produce successful surround material, but also to guarantee compatibility in
conventional stereo and monophonic playback.
Typically, the two channels generated by the SEU4 are distributed by conventional stereo
means such as consumer video formats and broadcast systems. Listeners who wish to
recreate four-channel input material can optionally decode the program material using a
surround decoding device. These are being manufactured by many consumer equipment
manufacturers and can be identified by a Dolby Surround logo on the equipment.
Home decoding of the two-channel output of the SEU4 is considered desirable but
optional. The two-channel material from the SEU4 is compatible with non-decoded, two
loudspeaker playback. The two-channel output of the SEU4 can also be considered to be
mono-compatible provided the original four-channel program material has been allocated
in a manner consistent with monophonic playback.
Note:
The Model SEU4 is not designed for mastering Dolby film sound formats. Dolby film
formats can only be produced with a valid Dolby Film Service agreement under
supervision of a Dolby Film Sound consultant. For further information please contact
Dolby Laboratories.
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