Post-compression hidden data transport

A method for recovering auxiliary data subband samples representative of an auxiliary data signal from a compressed digital data stream, said auxiliary data subband samples being provided by modulating a first data carrier sequence by said auxiliary data signal, said auxiliary data subband samples being carried with audio subband samples in combined subband samples in said compressed digital data stream, comprising the steps of:

• recovering said combined subband samples from said data stream;
• providing a recovery data carrier sequence corresponding to said first data carrier sequence;
• and
• demodulating said combined subband samples using said recovery data carrier sequence to recover said auxiliary data subband samples from said recovered combined subband samples.

An encoder for providing auxiliary data subband samples, which are representative of an auxiliary data signal, in a compressed subband coded digital audio data stream, comprising:

• an input terminal for receiving said digital audio data stream and providing a plurality of audio subband samples;
• a data carrier generator for providing a data carrier sequence;
• a modulator for modulating said data carrier sequence by said auxiliary data signal to provide said auxiliary data subband samples;
• a combiner coupled to said modulator for combining said auxiliary data subband samples with corresponding audio subband samples to produce combined subband samples in which said auxiliary data subband samples are carried substantially inaudibly;
• and
• an output terminal coupled to said combiner for providing said combined subband samples for transport in said digital audio data stream.

A decoder for recovering auxiliary data subband samples which are representative of an auxiliary data signal from a compressed digital data stream, said auxiliary data subband samples being provided by modulating a first data carrier sequence by said auxiliary data signal, said auxiliary data subband samples being carried with audio subband samples in combined subband samples in said compressed digital data stream, comprising:

• means for recovering said combined subband samples from said compressed digital data stream;
• means for providing a recovery data carrier sequence corresponding to said first data carrier sequence;
• and
• a demodulator for demodulating said combined subband samples using said recovery data carrier sequence to recover said auxiliary data subband samples from said recovered combined subband samples.

A compressed digital data storage media, comprising:

• (i) storage means for storing combined subband samples including audio subband samples which represent an audio signal, and auxiliary data subband samples which represent an auxiliary data signal;
• said auxiliary data subband samples being provided by modulating a data carrier sequence by said auxiliary data signal over at least one subband corresponding to said audio subband samples;
• said auxiliary data signal being carried substantially inaudibly in said audio signal;
• said auxiliary data signal being spectrally shaped according to said audio signal;
• and
• (ii) means for allowing the recovery of said auxiliary data signal from said auxiliary data subband samples.