Avid Technology Limited

Personics Corporation

John C Weitz

Hugh Macdonald

David D Clementson

J Douglas Rollow, Iv

Michael K Poimboeuf

Peter A Richert

Thomas D Sharples

Robert Jiro Snavely

Dave Conry

Chris Michael

Charles E Garvin

Michael Poimboeuf

Scott C Bittle

Georges Berenger

Ichyterra Ganapathy

Multi-level catamaran

A transmission medium and protocol is provided for bi-directional communication between an audio system and a peripheral device. The transmission medium includes a communication medium for communicating data and a communication medium for communicating a clock signal that corresponds to a transmission rate of bits on the other communication media. By transmitting the clock signal on a separate communication medium from the data, clock recovery is avoided. There may be multiple clock domains. By having multiple clock domains, multiple sample rates can be supported. Synchronization information is embedded in the signal by using run length limiting markers between the data for each channel and a synchronization word having more consecutive zero bits than the number of bits for each channel. One or more channels may be dedicated to providing control and status information.

Audio and music data transmission medium and transmission protocol

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. The stack rack recovers the audio sample clock from data received from the FOH rack and synchronizes its receive and transmit operations to this recovered clock. The FOH rack recovers the audio sample clock from data received from the stage rack and synchronizes its receive operations to this recovered clock. The FOH rack may include an embedded computer that processes the digital audio data, and may include DSP processing that handles so-called plug-in software. A digital audio workstation or sequencer also may be connected to the FOH rack to either record the live presentation or to inject edited, recorded audio into the live presentation.

System for live audio presentations

A clock signal and data is recovered from a variable rate signal including biphase mark encoded digital audio data. Such recovery involves regularly determining a minimum or maximum pulse width in the biphase mark encoded digital audio data using a high frequency clock. This pulse width is used to define a window in which a transition in the biphase mark encoded digital audio data may be detected. If a transition occurs in the defined window, a data one is output; if a transition does not occur in the defined window, a data zero is output. The recovered clock has a period of twice the minimum pulse width. A minimum or maximum pulse width can be tracked with an accumulator with decay. In particular, if the data rate of the input signal becomes faster, the shortest pulse will become shorter and a minimum value stored by the accumulator will become shorter. If the data rate of the input signal becomes slower, the longest pulse will become longer and any maximum value stored by the accumulator will become longer. However, if a minimum is stored and the input signal becomes slower, or if a maximum is stored and the input signal becomes faster, the stored minimum or maximum values would not otherwise change. By incorporating decay, the stored value changes over time towards a larger value (if a minimum is stored) or a smaller value (if a maximum is stored) to a limit. By regularly updating the determined minimum or maximum pulse width, the rate of the input signal may vary over time and still permit recovery of the clock and data signals. By using a window in which a transition is detected, jitter in the input signal is tolerated and gradual changes in input rate may be tracked.

Variable data rate receiver

Method and apparatus for addressably writing digital representations of high-fidelity sound recordings in a non-mapped digital storage device, such as a CD music ROM, using conventional PCM (pulse code modulated) equipment, but in a more condensed and efficiently sampled ADM (adaptive delta modulated) format thereby providing high-density addressable storage of several thousand recordings in a single music ROM jukebox as well as high-speed information transfers. The invention enables communication and control links between conventional digital audio processors and conventional microcomputers. Timing data is embedded in the ADM formatted and blocked data file. The microcomputer is utilized for editing ADM data, inserting catalog data, and transferring the data file to a standard PCM file writer suitable for making non-mapped CD music ROMs containing addressable ADM data files on conventional equipment utilized in the indstry. Encoding is performed by Dolby delta-link ADM encoding to achieve time-domain condensation of information content, and analog signals representing the sound recording are peak-limited prior to preprocessing by Dolby B noise reduction techniques. CD music ROMs produced thereby are utilized in high-speed reproduction systems or for addressable computer access in high-volume archival storage systems.

System for encoding sound recordings for high-density storage and

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. A high-speed reproduction device, under control of a desk top personal computer, extracts timing and ADM data from the CD music ROM at high speed and controls high-speed tape drives to compile selected recordings on a single cassette tape in a form compatible with Dolby B noise reduction.

High-speed reproduction facility for audio programs

Growing community of inventors

Belmont, CA, United States of America

John C Weitz