Inventors:
Ray M. Dolby - San Francisco CA
Ioan R. Allen - San Francisco CA
Randolph G. Pauker - Berkeley CA
International Classification:
G11B 509
G11B 502
H04N 594
Abstract:
A "hybrid" encoder has a characteristic action suitable for substantially full complementary playback in an audio signal transmission or recording system using decoders designed for one type complementary encode/decode system while permitting compatible decoding with decoders designed for use with another type complementary encode/decode system, or playback without any special decoders at all. The hybrid encoder is a series or parallel arrangement of two encoders that are modifications of standard encoders used in the two systems. In the preferred embodiments the two systems are A-type noise reduction and spectral recording. A variable degree of hybrid encoding is provided by varying the characteristic controlling circuit parameters in the two encoders, or in a preferred embodiment, by providing a variable combining arrangement that selects selects from the outputs of a hybrid encoder and an unmodified encoder (spectral recording).