SYSTEM AND METHOD FOR ENCODING AN AUDIO SIGNAL FOR USE IN BROADCAST PROGRAM IDENTIFICATION SYSTEMS, BY ADDING INAUDIBLE CODES TO THE AUDIO SIGNAL

摘要

Blocks of audio are encoded based upon corresponding first and second frequencies. The first and second frequencies are hopped from block to block. An audio quality measure (AQM) is computed for each block of audio such that, if x out of y blocks of audio have an AQM greater than a first predetermined threshold, encoding is suspended. For example, x may be nine and y may be 16. Also, if a ratio of the energy in a front part of a block of audio to the energy in a rear part of the block of audio is greater than a second predetermined threshold, that block of audio is not encoded even though x out of y blocks of audio have an AQM greater than the first predetermined threshold. Multiple distributors of the audio may encode the audio with their corresponding identities using the above processes.