System for live audio presentations

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. 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.