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.