MULTI-MODE AUDIO RECOGNITION AND AUXILIARY DATA ENCODING AND DECODING

• US 20140108020A1
• Filed: 03/15/2013
• Published: 04/17/2014
• Est. Priority Date: 10/15/2012
• Status: Active Grant

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Sharma, Ravi K., Bradley, Brett A., Bai, Yang, Thagadur Shivappa, Shankar, Kamath, Ajith, Filler, Tomas, Gurijala, Aparna, Cushman, David A.
• Granted Patent: US 9,401,153 B2
• Time in Patent Office: Days
• US Class Current: 704/500
• CPC Class Codes: G10L 19/018 Audio watermarking, i.e. embedding inaudible data in the audio signal
• CPC Class Codes: G10L 19/02 using spectral analysis, e.g. transform vocoders or subband vocoders
• CPC Class Codes: G10L 19/028 Noise substitution, i.e. substituting non-tonal spectral components by noisy source comfort noise for discontinuous speech transmission G10L19/012
• CPC Class Codes: G10L 25/87 Detection of discrete points within a voice signal

Abstract

Audio signal processing enhances audio watermark embedding and detecting processes. Audio signal processes include audio classification and adapting watermark embedding and detecting based on classification. Advances in audio watermark design include adaptive watermark signal structure data protocols, perceptual models, and insertion methods. Perceptual and robustness evaluation is integrated into audio watermark embedding to optimize audio quality relative the original signal, and to optimize robustness or data capacity. These methods are applied to audio segments in audio embedder and detector configurations to support real time operation. Feature extraction and matching are also used to adapt audio watermark embedding and detecting.

Claims

1. A method of embedding a watermark in an electronic audio signal, the method comprising:

classifying the audio signal according to audio type;

based on the audio type, selecting an audio watermark type and insertion method; and

inserting a watermark of the selected audio watermark type according to the selected insertion method.

2. The method of claim 1 wherein the classifying comprises discriminating audio segments based on types, including speech and music.

3. The method of claim 1 including embedding a code conveying the watermark type in the audio signal.

4. The method of claim 3 wherein the code comprises a Hadamard code.

5. The method of claim 1 wherein classifying comprises computing a feature vector of an audio segment, and determining audio type by submitting the feature vector to a database, where feature vectors are classified by audio type.

6. The method of claim 1 wherein classifying comprises transforming an audio segment according to an ear model that models human auditory response to the audio segment and provides a measure of perceptible features of the audio segment, and from the measure of perceptible features, selecting a watermark type.

9. The method of claim 1 wherein classifying comprises determining whether an audio segment is stationary or non-stationary, and adapting resolution of a perceptual model based on whether the audio segment is stationary or non-stationary.

10. The method of claim 1 wherein classifying comprises detecting spectral peaks and classifying the audio based on the detected spectral peaks;

and selecting a watermark type and insertion method in which spectral peaks are adjusted to correspond to a bump structure of a corresponding watermark signal.

7. The method of 6 including analyzing ear model output variables providing perceptible energy in bands to discern audio class.

8. The method of 7 wherein analyzing comprises mapping a feature vector derived from the perceptible energy in the bands to an audio class in a feature vector database.

11. An audio processing system comprising:

a classifier for classifying the audio signal according to audio type;

a watermark embedder, in communication with the classifier for receiving the audio type, and based on the audio type, selecting an audio watermark type and insertion method; and

for inserting a watermark of the selected audio watermark type according to the selected insertion method.

12. The system of claim 11 wherein the classifier discriminates audio segments based on types, including speech and music.

13. A method of detecting a watermark in an electronic audio signal, the method comprising:

classifying the audio signal according to audio type;

based on the audio type, determining an audio watermark type and insertion method; and

detecting a watermark of the selected audio watermark type according to the selected insertion method.

14. The method of claim 13 wherein the classifying comprises discriminating audio segments based on types, including speech and music.

15. An audio processing system comprising:

a classifier for classifying the audio signal according to audio type;

a watermark detector, in communication with the classifier for receiving the audio type, and based on the audio type, determining an audio watermark type and insertion method; and

for detecting a watermark of the selected audio watermark type according to the selected insertion method.