Measuring quality of service of broadcast multimedia signals using digital watermark analyses

• US 7,277,468 B2
• Filed: 09/10/2001
• Issued: 10/02/2007
• Est. Priority Date: 09/11/2000
• Status: Expired due to Term

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Levy, Kenneth L., Tian, Jun, Brunk, Hugh L.
• Primary Examiner(s): TRAN, KHANH C
• Application Number:
  US09/951,143
• Publication Number:
  US 20020076084A1
• Time in Patent Office: 2,213 Days
• Field of Search: 375/130, 713/176, 358/3.28, 380/201, 380/203, 380/28, 380/55
• US Class Current: 375/130
• CPC Class Codes: G06T 1/0042 Fragile watermarking, e.g. so as to detect tampering
• CPC Class Codes: G06T 1/0071 using multiple or alternating watermarks
• CPC Class Codes: G06T 2201/0051 Embedding of the watermark in the spatial domain
• CPC Class Codes: H04L 67/06 specially adapted for file transfer, e.g. file transfer protocol [FTP]
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: H04N 1/32154 Transform domain methods H04N1/32309 takes precedence
• CPC Class Codes: H04N 1/3216 using Fourier transforms
• CPC Class Codes: H04N 17/004 for digital television systems
• CPC Class Codes: H04N 21/4425 Monitoring of client processing errors or hardware failure
• CPC Class Codes: H04N 21/8358 involving watermark protecting executable software by watermarking G06F21/16; image watermarking in general G06T1/0021; watermarks inserted in still images for transmission purposes H04N1/32144; inserting watermarks during video coding H04N19/467

Abstract

The disclosure details a method of measuring the quality of service of broadcast media signals by analyzing digital watermarks embedded in the received broadcast signal. This method enables the quality of the broadcast video or audio signal to be measured without having the original version of the signal before broadcast transmission. Instead, the method analyzes the strength or quality of the embedded digital watermark to determine the quality of the received broadcast signal. The degradation of a watermark signal is used to measure quality of service of broadcast signals, such as audio and video.

Claims

1. A method of measuring quality of service of a broadcast media signal using a digital watermark embedded in the broadcast media signal, the method comprising:

extracting a digital watermark from the broadcast media signal; and

evaluating the extracted digital watermark relative to a reference digital watermark to measure degradation in quality of service of the broadcast media signal based on differences between the extracted and reference digital watermarks;

wherein the evaluating includes comparing signal peaks of the broadcast media signal and the reference digital watermark.

2. The method of claim 1 wherein the signal peaks comprise frequency domain peaks.

3. The method of claim 1 wherein the evaluating includes measuring signal strength of the extracted watermark by measuring differences between a watermark message signal decoded from the broadcast media signal and a reference watermark message signal.

4. The method of claim 3 wherein the watermark message signal decoded from the broadcast media signal is spread spectrum demodulated from the broadcast media signal.

5. A method of measuring quality of service of a broadcast media signal using a digital watermark embedded in the broadcast media signal, the method comprising:

extracting a digital watermark from the broadcast media signal; and

evaluating the extracted digital watermark relative to a reference digital watermark to measure degradation in quality of service of the broadcast media signal based on differences between the extracted and reference digital watermarks;

wherein the evaluating includes comparing signal peaks of the broadcast media signal and the reference digital watermark.

6. The method of claim 5 wherein the signal peaks comprise frequency domain peaks.

7. A method of assessing the quality of a media signal that has undergone processing, comprising:

steganographically encoding the signal with a watermark by a process that includes transforming the signal into plural coefficients, and adjusting a relationship between first and second coefficients to a known value;

processing the encoded media signal; and

analyzing the processed media signal by a process that includes transforming the processed media signal into plural coefficients, detecting a relationship between said first and second coefficients, and comparing said detected relationship versus said known value to thereby discern qualitative information about the processing of said media signal.

8. The method of claim 7 wherein said relationship comprises a ratio between strengths of said first and second coefficients.

9. A method of assessing the quality of a media signal that has undergone processing, comprising:

encoding the signal with a watermark by a process that includes modifying the signal to include a steganographic calibration signal by which affine transformation of the signal can be identified and compensated for, said calibration signal including peaks at first and second frequencies, said peaks having first and second values, respectively, said values having a first relationship;

processing the encoded media signal; and

analyzing the processed media signal by a process that includes detecting said peaks therein, determining a second relationship between the strengths thereof, and comparing the second relationship to the first relationship, to thereby discern qualitative information about the processing of said media signal.

10. The method of claim 9 wherein said first and second relationships comprise ratios between strengths of said first and second coefficients.

11. A method of measuring quality of service of a broadcast media signal using a digital watermark embedded in the broadcast media signal, the method comprising:

extracting a digital watermark from the broadcast media signal; and

evaluating the extracted digital watermark relative to a reference digital watermark to measure degradation in quality of service of the broadcast media signal based on differences between the extracted and reference digital watermarks;

wherein the media signal comprises video that has been conveyed in MPEG form, and the extracting includes decoding a digital watermark signal encoded in frequency coefficients of a wavelet domain transformation of said video.

12. The method of claim 11 wherein the extracting includes decoding a digital watermark signal encoded in frequency coefficients of a wavelet domain transformation of a luminance component of said video.

13. The method of claim 11 wherein the extracting includes decompressing the video from the MPEG form in which it was conveyed.

14. The method of claim 11 the evaluating includes comparing a sequence of encoded message symbols with a sequence of decoded message symbols, to identify symbol errors therebetween.

15. A method of measuring quality of service of a broadcast media signal using a digital watermark embedded in the broadcast media signal, the method comprising:

extracting a digital watermark from the broadcast media signal, the digital watermark comprising a sequence of symbols; and

evaluating extracted digital watermark data relative to reference digital watermark data to measure degradation in quality of service of the broadcast media signal;

wherein the evaluating includes determining a number of correctly detected watermark symbols out of a total set of watermark symbols.

16. The method of claim 15 that includes:

applying an error correction algorithm to the extracted sequence of symbols to produce an original message payload corresponding thereto;

applying an error correction-encoding processing to said original message payload, to generate an originally embedded sequence of symbols; and

comparing the extracted sequence of symbols with said original embedded sequence of symbols.

17. A method for measuring quality of service of a distributed media signal comprising:

originally encoding digital watermark data in the media signal prior to distribution of said signal from a first computer;

alter distribution, decoding digital watermark data from the distributed signal at a second computer distinct from the first; and

comparing the encoded and decoded digital watermark data to assess quality of service;

wherein the method includes determining the originally encoded digital watermark data at the second computer, from the distributed signal, without separately communicating information about the originally encoded digital watermark data from the first computer to the second computer.