Abstract: In a live audio presentation system, a stage rack and a front of house rack are interconnected by a transmission medium that transmits digital audio data and control information between them. Packets of digital audio data and control information are sent at the audio sampling rate. The packets of data are encoded using an encoding technique that provides unique codes that may be detected, thus enabling clock recovery of a clock signal embedded in the data packets. Data packets may include data for error checking. A serial digital transmission medium may be used as the transmission medium. Such a transmission medium uses low voltage signals and supports high bit rates. The system is synchronized by the FOH rack which transmits data to the stage rack according to a local audio sample clock or an external audio sample clock to which it synchronizes. This clock is embedded in data packets sent to the stage rack.

Abstract: In a live audio presentation system, a stage rack and a front of house rack are interconnected by a transmission medium that transmits digital audio data and control information between them. Packets of digital audio data and control information are sent at the audio sampling rate. The packets of data are encoded using an encoding technique that provides unique codes that may be detected, thus enabling clock recovery of a clock signal embedded in the data packets. Data packets may include data for error checking. A serial digital transmission medium may be used as the transmission medium. Such a transmission medium uses low voltage signals and supports high bit rates. The system is synchronized by the FOH rack which transmits data to the stage rack according to a local audio sample clock or an external audio sample clock to which it synchronizes. This clock is embedded in data packets sent to the stage rack.

Abstract: Multiple media devices are synchronized in a multi-media system having a computer system, a plurality of media devices, and a display system. Each media device to be synchronized receives a front-end synchronization signal that periodically increments a front-end counter. The front-end counter represents an unadjusted system time (UST). The media device obtains a frame of data to be displayed from a computer system. The media device also receives a back-end synchronization signal that periodically increments a back-end counter each time a frame of data is to be displayed. The back-end counter represents a media stream count (MSC). UST and MSC data are periodically transmitted to the computer system for analysis and use by a synchronization algorithm. Specifically, UST is transmitted to the computer system each time a frame of data is obtained, and a UST/MSC pair is transmitted to the computer system each time a frame of data is displayed.

Abstract: Direct synthesis of a digital audio sample clock from a digital video sample clock is achieved by using a numerically controlled oscillator driven by the digital video sample clock. A phase accumulator increments a phase increment at the frequency of the digital video sample clock, the phase increment being a function of a desired frequency for the digital audio sample clock, the frequency of the digital video sample clock and the bit precision of the accumulator. The accumulated phase output from the accumulator is converted into a sine wave signal at the desired audio frequency from which the digital audio sample clock is derived.

Abstract: A method for synchronization of a digital audio signal sampled at a standard audio frequency with the corresponding digital video signal sampled at a standard video frequency associates an integer number of samples of the digital audio signal with each video field of the digital video signal. The number of audio samples per video field is determined by the audio sample rate rounded up to the nearest integer. Every N video fields where the number of digital audio samples is an integer value, the digital audio signal is resynchronized with the digital video signal by repeating the digital audio samples at the end of video field N that correspond to video field N+1. At reception the same digital audio samples are skipped at the end of video field N.

Abstract: Data processing system for high-speed reproduction of musical recordings at a point-of-sale terminal utilizes optical CD music ROM banks of master programs prerecorded by a Dolby ADM (adaptive delta modulated) technique to condense their "information" content. Condensation permits higher data throughput during high-speed reproduction. In a "premastering" process to make encoded masters, a special multiplexer board provides interfacing between Dolby ADM digital audio data and a conventional data processing system. The multiplexer board performs computer-like data blocking and also writes a unique sync code directly in the data block. The data processing system also catalogs and edits the blocked digital audio; places encrypted catalog, pricing, and other indicia in the data file representing the music; and sends the data file to convention 16-bit PCM file writer for making the encoded CD music ROMs which contain the ADM data representing the encoded audio program.