Method and system of digital watermarking for compressed audio

• US 20040059918A1
• Filed: 10/07/2003
• Published: 03/25/2004
• Est. Priority Date: 12/15/2000
• Status: Abandoned Application

• Current Assignee: Agency For Science Technology and Research
• Original Assignee: Agency For Science Technology and Research
• Inventors: Xu, Changsheng
• Application Number:
  US10/450,736
• Publication Number:
  US 20040059918A1
• Time in Patent Office: Days
• US Class Current: 713/176
• CPC Class Codes: G10L 19/018 Audio watermarking, i.e. embedding inaudible data in the audio signal

Abstract

The invention provides a system and method of rapidly embedding and extracting digital watermarks into and from digital compressed audio content. The watermark may be embedded or extracted in both compressed and uncompressed formats. While the watermark is inaudible within its host signal and extremely difficult to remove via unauthorized access, it may be easily extracted by an authorized user. The watermark is also highly resistant to incidental and intentional distortion, alteration or copying. The embedded watermark does not adversely affect the audio quality, e.g., audibility, or result in the alteration of the bit rates in a compressed domain signal and is compatible with state-of-the-art signal processing methods and phenomenon, such as D/A and A/D conversions, and the overlay of noise and electrical and magnetic interference, filtering, re-sampling, and in particular, decoding and re-encoding processes. FIG. 1 of the drawings shall accompany the publication of the abstract.

Claims

1. A method to embed a watermark in a digitally umcompressed audio signal, comprising:

segmenting an original audio signal into a plurality of frames;

extracting feature parameters from each of the plurality of frames;

assigning, based on the feature parameters and the masking threshold, an embedding framework for each of the plurality of frames,

embedding the watermark information into a watermarked audio frame; and

compressing the watermarked audio signal.

2. A method to embed a watermark in a compressed audio signal, comprising:

segmenting the compressed audio signal into a plurality of frames;

extracting scale factor selection information (SCFI) for each of the plurality of frames;

locating a position of a scale factor band (SFB) for each of the plurality of frames;

selecting at least one scale factor corresponding to at least one high-frequency sub-band for each of the plurality of frames; and

embedding a synchronization code into the at least one scale factor.

3. A method to embed a watermark in a partially uncompressed domain, comprising:

segmenting a compressed audio signal into a plurality of frames;

decoding each of the plurality of frames;

extracting a feature parameter from each of the plurality of decoded frames;

computing a psychoacoustic model for each of the plurality of decoded frames;

selecting frames suitable for embedding watermark information based on the feature parameters and the masking threshold;

embedding the watermark information into the selected frame, creating an embedded frame;

re-encoding the embedded frames; and

reconstructing the embedded frames and non-embedded frames to generate a watermarked compressed audio signal.

4. A method to extract an embedded watermark from a watermarked uncompressed digital audio signal, comprising:

dividing the watermarked digital audio signal into a plurality of frames;

determining a magnitude of an autocorrelation of the embedded watermark'"'"'s cepastrum at a location in each of the plurality of frames; and

mapping a plurality of data bits of each frame into code that may be correlated with an original watermark.

5. A method to extract an embedded watermark from a watermarked compressed digital audio signal, comprising:

dividing the watermarked compressed digital audio signal into a plurality of frames;

locating a scale factor band for each of the plurality of frames;

determining a synchronization code of the scale factor band for each of the plurality of frames; and

detecting a watermark sequence to recover the embedded watermark.

6. A method to extract an embedded watermark from a partially uncompressed domain, comprising:

dividing a watermarked compressed audio signal into a plurality of frames;

decoding each of the plurality of frames;

extracting feature parameters from each of the plurality of decoded frames;

computing a psychoacoustic model for each of the plurality of decoded frames;

detecting an embedded frame based on the feature parameters and the masking threshold; and

extracting the watermark.

7. A computer-readable medium including instructions to perform a method to embed a watermark into a digitally uncompressed audio signal, comprising:

a first unit to segment an original audio signal into a plurality of frames;

a second unit to extract feature parameters from each of the plurality of frames;

a third unit to assign, based on the feature parameters and the masking threshold, an embedding framework for each of the plurality of frames;

a fourth unit to embed the watermark information into the audio frame; and

a fourth unit to compress the watermarked audio signal.

8. A computer-readable medium including instructions to perform a method to embed a watermark in a compressed audio signal, comprising:

a first unit to segment the compressed audio signal into a plurality of frames;

a second unit to extract scale factor selection information (SCFI) for each of the plurality of frames;

a third unit to locate a position of a scale factor band (SFB) for each of the plurality of frames;

a fourth unit to select at least one scale factor corresponding to at least one high-frequency sub-band for each of the plurality of frames; and

a fifth unit to embed a synchronization code into the at least one scale factor.

9. A computer-readable medium including instructions to perform a method to embed a watermark in a partially uncompressed domain, comprising:

a first unit to segment a compressed audio signal into a plurality of frames;

a second unit to decode each of the plurality of frames;

a third unit to extract a feature parameter from each of the plurality of decoded frames;

a fourth unit to compute a psychoacoustic model for each of the plurality of decoded frames;

a fifth unit to select frames suitable to embed watermark information in, based on the feature parameters and the masking threshold;

a sixth unit to embed the watermark information into the selected frame, creating an embedded frame;

a seventh unit to re-encode the embedded frames; and

an eighth unit to reconstruct the embedded frames and non-embedded frames to generate a watermarked compressed audio signal.

10. A computer-readable medium including instruction to perform a method to extract an embedded watermark from a watermarked uncompressed digital audio signal, comprising:

a first unit to divide the watermarked uncompressed digital audio signal into a plurality of frames;

a second unit to determine a magnitude of an autocorrelation of the embedded watermark'"'"'s cepastrum at a location in each of the plurality of frames; and

a third unit to map a plurality of data bits of each frame into code that may be correlated with an original watermark.

11. A computer-readable medium including instructions to perform a method to extract an embedded watermark from a watermarked compressed digital audio signal, comprising:

a first unit to divide the watermarked compressed digital audio signal into a plurality of frames;

a second unit to locate a scale factor band for each of the plurality of frames;

a third unit to determine a synchronization code of the scale factor band for each of the plurality of frames; and

a fourth unit to detect a watermark sequence to recover the embedded watermark.

12. A computer-readable medium including instructions to perform a method to extract an embedded watermark from a partially uncompressed domain, comprising:

a first unit to divide a watermarked compressed audio signal into a plurality of frames;

a second unit to decode each of the plurality of frames;

a fourth unit to extract feature parameters from each of the plurality of decoded frames;

a fifth unit to compute a psychoacoustic model for each of the plurality of decoded frames; and

a sixth unit to detect au embedded frame based on the feature parameters and the masking threshold; and

a seventh unit to extract the watermark.