Methods and apparatus for embedding codes in compressed audio data streams

An article of manufacture comprising machine readable instructions which, when executed, cause a machine to at least:

• access a first scale factor and a first set of mantissas for a first set of transform coefficients included in a compressed audio stream, the first set of transform coefficients corresponding to a first band of a compression standard;
• quantize a second set of transform coefficients based on a second scale factor corresponding to the first scale factor reduced by a unit of resolution to determine a second set of mantissas, the second set of transform coefficients corresponding to the first band of the compression standard and including the watermark;
• and
• replace the first scale factor with the second scale factor and the first set of mantissas with the second set of mantissas to modify the first set of transform coefficients to embed a watermark in the compressed audio stream.

An apparatus to embed a watermark in a compressed audio stream, the apparatus comprising:

• an embedding unit to:
• access a first scale factor and a first set of mantissas for a first set of transform coefficients included in the compressed audio stream, the first set of transform coefficients corresponding to a first band of a compression standard;
• quantize a second set of transform coefficients based on a second scale factor corresponding to the first scale factor reduced by a unit of resolution to determine a second set of mantissas, the second set of transform coefficients corresponding to the first band of the compression standard and including the watermark;
• and
• replace the first scale factor with the second scale factor and the first set of mantissas with the second set of mantissas to modify the first set of transform coefficients to embed the watermark in the compressed audio stream to produce a watermarked compressed audio stream;
• a modification unit to:
• reconstruct an uncompressed audio stream based on the first set of transform coefficients;
• and
• embed the watermark in the reconstructed audio stream to determine the second set of transform coefficients;
• and
• a repacking unit to output the watermarked compressed audio stream for transmission.