# US 8,099,285 B2 · Temporally accurate watermarking system and method of operation

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- Number: US 8,099,285 B2
- Document ID: US8099285B2
- Status: Granted
- Kind: B2
- Application number: 12/001,851
- Filed: 2007-12-13
- Published: 2009-06-18
- Granted: 2012-01-17
- Earliest claimed: 2007-12-13
- Assignees: DTS, Inc.
- Inventors: Brandon Smith; Jeffrey Thompson; Aaron Warner
- Web page: https://patentgrep.com/patent/US8099285B2

## CPC

- G11B 20/00086: {Circuits for prevention of unauthorised reproduction or copying, e.g. piracy (indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00)}
- G10L 19/018: Audio watermarking, i.e. embedding inaudible data in the audio signal
- G11B 20/00181: {using a content identifier, e.g. an international standard recording code [ISRC] or a digital object identifier [DOI]}
- G11B 20/00891: {embedded in audio data}
- G11B 2020/00028: {Advanced audio coding [AAC]}
- G11B 2020/00057: {MPEG-1 or MPEG-2 audio layer III [MP3]}
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)
- G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING

## Abstract

A system for identifying audio data is provided. The system includes a transform system receiving left channel audio data and right channel audio data and generating a plurality of frequency bins of left channel magnitude data, left channel phase data, right channel magnitude data and right channel phase data. A watermarking system receives watermarking data and modifies predetermined frequency bins of the left channel phase data and the right channel phase data to encode the watermarking data. A magnitude system receives the left channel magnitude data and the right channel magnitude data and increases the left channel magnitude data and the right channel magnitude data for one or more of the predetermined frequency bins to a threshold level if the left channel magnitude data and the right channel magnitude data for the corresponding frequency bin is less than the threshold level.

## Claims

### Claim 1

A system for identifying audio data comprising:
a transform system for receiving left channel audio data and right channel audio data and electronically generating a plurality of frequency bins of left channel magnitude data, left channel phase data, right channel magnitude data and right channel phase data;
a watermarking system for receiving watermarking data and electronically modifying predetermined frequency bins of the left channel phase data and the right channel phase data to encode the watermarking data;
a magnitude system for receiving the left channel magnitude data and the right channel magnitude data and increasing the left channel magnitude data and the right channel magnitude data for one or more of the predetermined frequency bins to a threshold level if the left channel magnitude data and the right channel magnitude data for the corresponding frequency bin are less than the threshold level; and
a timing system for receiving a plurality of bits of timing data and modifying two or more predetermined frequency bins of the left channel phase data and two or more predetermined frequency bins of the right channel phase data to encode each bit of the timing data;
wherein the predetermined frequency bins of the left channel phase data and the right channel phase data that are used to encode timing data are modified by different phase angles than the predetermined frequency bins of the left channel phase data and the right channel phase data that are used to encode watermarking data.

### Claim 2 (depends on 1)

The system of claim 1 further comprising a frame adjustment system for receiving frame sequence data and modifying the timing data based on the frame sequence data.

### Claim 3 (depends on 1)

The system of claim 1 wherein the transform system comprises:
a right channel transform system for receiving the right channel audio data and generating the plurality of frequency bins of the right channel magnitude data and the right channel phase data;
a left channel transform system for receiving the left channel audio data and generating the plurality of frequency bins of the left channel magnitude data and the left channel phase data.

### Claim 4 (depends on 1)

The system of claim 1 wherein the magnitude system comprises:
a right channel magnitude system for receiving the right channel magnitude data and increasing the right channel magnitude data for one or more of the predetermined frequency bins to a threshold level if the right channel magnitude data for the corresponding frequency bin is less than the threshold level; and
a left channel magnitude system for receiving the left channel magnitude data and increasing the left channel magnitude data for one or more of the predetermined frequency bins to a threshold level if the left channel magnitude data for the corresponding frequency bin is less than the threshold level.

### Claim 5

A method for identifying audio data comprising:
receiving left channel audio data and right channel audio data;
converting the left channel audio data and the right channel audio data into a plurality of bins of left channel phase data, left channel magnitude data, right channel phase data and right channel magnitude data;
encoding watermark data by electronically modifying a phase difference between the left channel phase data and the right channel phase data for each of a plurality of predetermined bins;
adjusting the left channel magnitude data and the right channel magnitude data for each of the plurality of predetermined bins to a predetermined threshold if the left channel magnitude data and the right channel magnitude data is less than the predetermined threshold; and
receiving a plurality of bits of timing data and modifying two or more predetermined frequency bins of the left channel phase data and two or more predetermined frequency bins of the right channel phase data to encode each bit of the timing data;
wherein the predetermined frequency bins of the left channel phase data and the right channel phase data that are used to encode timing data are modified by different phase angles than the predetermined frequency bins of the left channel phase data and the right channel phase data that are used to encode watermarking data.

### Claim 6 (depends on 5)

The method of claim 5 further comprising converting the plurality of bins of modified left channel phase data, adjusted left channel magnitude data, modified right channel phase data and adjusted right channel magnitude data into watermarked left channel audio data and watermarked right channel audio data.

### Claim 7 (depends on 5)

The method of claim 5 wherein encoding the watermark data by modifying the phase difference between the left channel phase data and the right channel phase data for each of the plurality of predetermined bins comprises:
modifying the phase difference between the left channel phase data and the right channel phase data for each of a first plurality of predetermined bins based on a first bit of the watermark data; and
modifying the phase difference between the left channel phase data and the right channel phase data for each of a second plurality of predetermined bins based on a second bit of the watermark data.

### Claim 8 (depends on 5)

The method of claim 5 wherein encoding the watermark data by modifying the phase difference between the left channel phase data and the right channel phase data for each of the plurality of predetermined bins comprises:
modifying the phase difference between the left channel phase data and the right channel phase data for each of a first plurality of predetermined bins based on a first bit of the watermark data; and
modifying the phase difference between the left channel phase data and the right channel phase data for each of a second plurality of predetermined bins based on the first bit of the watermark data.