Digital Audio Synchronization in a Mixed-Media Plant

Charles Meyer

Digital audio is not new; digital audio plant implementation is. The advent of low-cost digital video tape recorders (DVTRs) has for the first time provided the performance advantage associated with digital in the video post-production market. This opportunity is not without cost. The multiple formats used in production work include frame rates of 24, 25, 29.97, and 30 frames/sec. Any two or three of these formats may be in use concurrently, and the audio information that is now in the digital domain and synchronized to the picture must seamlessly make the transition across these format boundaries. Despite the best efforts to provide a fully synchronized plant, a point will be reached at which the only solution is audio sample-rate conversion. This conversion process, analog or digital, is not a trivial task. Every effort must be made to ensure proper phasing and the absolute minimum in distortion product generation during the conversion process. There are many products on the market that execute this function. The gamut ranges from off-line Macintosh software to three-rack-unit real-time hardware solutions. Each algorithm is based on common principles. Understanding these principles will enable more effective use of the equipment, more intelligent selection of which piece of equipment to use for what application, and more solutions to plant synchronization problems.

Print ISSN
Published
1993-02
Content type
Original Research
DOI
10.5594/J03812