Audio-digital processing system for demultiplexing stereophonic/quadriphonic input audio signals into 4-to-72 output audio signals

Fecha de publicación: 17/02/1981
Fuente: Wipo "digitalization"
An audio-digital processing system for processing and converting audio localization data from stereophonic or quadriphonic input audio signals into digital localization data. Said digital localization data is further processed into digital commutation data which demultiplexes said stereophonic or quadriphonic input audio signals into 4 . . . 16 . . . 72 output audio signals. PAL This system includes an Input Audio Processor and a Psychoacoustic Data Converter that process and convert each audio field of audio localization data into digital localization data, comprising: digital phase-angle differential, phasor differential, and amplitude differential data; digital field activity, threshold, and dropout data; and digital peak-amplitude strobes. Each type of digital localization data is updated in a corresponding memory for each change in the associated audio localization data. Each corresponding memory is enabled, inhibited, or cleared by respective digital threshold and/or dropout data which are responsive to predetermined audio signal-to-noise amplitude relationships. PAL This system also includes a Psychoacoustic Data Processor that processes each type of updated digital localization data into digital commutation data (a digital psychoacoustic process analogous to binaural fusion). This digital psychoacoustic process functions to: execute and priority evaluate demultiplexing decisions for each output audio field; restore the reproduced sound to near infinite separation; resolve monophonic, stereophonic, and quadriphonic directional ambiguities; and provide preselectable quadrifield operations that create permutations of listening experiences previously unobtainable from the same recording. These preselectable quadrifield operations function to create 16 selectable listening formats that interchange the original panpotted musical instrument/voice positions to other predetermined transducer positions; sequentially reposition, or continuously swirl the discrete sound images in the 360-degree quadrifield; and preselect 4 . . . 16 . . . 72 output audio channels to match the number of transducers configured by the listener. PAL This system further includes an Output Audio Processor that processes said stereophonic or quadriphonic input audio signals into output audio signals. The output audio signals are processed in accordance with the preselectable quadrifield operations into one or more of the following: discrete direct audio signals, a system bass signal that automatically tracks the Fletcher-Munson equal loudness contours, recovered/synthesized concert hall ambience signals, rear matrix encoded audio signals, recovered direct audio signals when rear matrix encoded audio signals predominate, and recovered rear matrix encoded audio signals when discrete direct audio signals predominate. PAL This system includes a Psychoacoustic Audio Demultiplexer that demultiplexes, in response to said digital commutation data, said output audio signals into 4, 5, 6, 8, 10, 12, 14, 16 . . . 72 preselected output audio channels and associated configuration of transducers. The demultiplexed and point-source reproduced discrete sound images establish a 360-degree walkthrough quadrifield that eliminates the stereophonic/qaudriphonic seat; a consumer problem initiated in 1924 and defying practical solution since the first commercial stereophonic tape recording in 1954 or disc recording in 1958.