Spread Spectrum Audio Steganography using Sub-band Phase Shifting - NGT Lab. - 台灣數位學習數位教學平台

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Spread Spectrum Audio Steganography using Sub-band Phase Shifting (12:30)

by Solomon, 2013-12-17 12:11, 人氣(1548)

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標題

1. Spread Spectrum Audio Steganography using Sub-band Phase Shifting

3. Spread Spectrum Audio Steganography

4.

5. M-sequence code

6. The spectrum is almost flat in the wide frequency range.

7. Then the output signal is power-adjusted below the masking threshold and added to the original audio.

8. Sub-Band Phase Shifting

9. In the case that the spreading rate is 511, 1 bit data can be embedded in a frame of 1022 samples, and the transmission speed is approximately 40bps. The coding rate of the error correcting code is 8.2% to provide the robustness of the embedded information against the aerial transmission at adistance of 1m. Therefore, the effective datatransmission speed becomes 3.3bps.

10. Correlations in each sub-band

11. Subjective Quality Testing

12. For the case of (1) and (2), the testing is made by setting the NMR (Noise Masking Ratio)In the case of (3) and (4), since the spread datasignal is not embedded, the scores were respectively 1and 2 regardless of the NRM.

13. Comparing (1) and (2), because of the phase shifting, the quality of (2) is (1) lower than that of (1) at every NMR. The quality difference is almost equal to the degradation of +3dB NRM. Therefore, if (2) has higher noise tolerance than +3dB of (1), (2) has better performance in total.

15. Conclusions

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