Method for altering AC-3 data streams using minimum computation

摘要

Methods and apparatus for broadcasting high quality audio “studio direct” with the same digital information employed in the studio by the video producer with AC-3 digital audio signals for broadcast to individual receiver decoders (IRD) include a method for altering meta data bits with minimum recalculation of cyclical redundancy check values. Control over individual data bits such as copyright bits is maintained by determining the bit status, comparing it to a preferred status, changing the status if it does not comply with the preferred status, and reevaluating cyclical redundancy check value in each data packet to avoid disruption in the data transmission. The calculation according to the present invention simplifies the hardware, storage and processing demands of previously known calculation techniques by forward and reverse comparisons of partial packet cyclic redundancy check (CRC) values.