US7035700B2
Expired / Lapsed
US
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Method and apparatus for embedding data in audio signals
Assignee: United States Department of the Air Force
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Filing: 2002-03-13
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Granted: 2006-04-25
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Expires: 2022-03-13
Abstract
Abstract Method and apparatus for embedding binary data in audio signals. The magnitude of the power spectrum at the perceptual holes of each frame of a host speech utterance, may be altered so as to embed digital data. The phase spectrum at perceptually masked spectral points of each frame of a host speech utterance, may also be altered so as to embed digital data.
Inventors
- 👤 Kaliappan Gopalan
- 👤 Daniel S. Benincasa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 12:55
CPC Classifications
G; G10; G10L; G10L19/00; G10L19/018; G11; G11B; G11B20/00; G11B20/00086; G11B20/00884; G11B20/00891; G10L25/00; G10L25/03; G10L25/21; H; H04; H04H; H04H20/00; H04H20/28; H04H20/30; H04H20/31
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
237 words
A method for embedding data in audio signals by altering the amplitude of a host signal audio power spectrum, comprising the steps of: inputting a host signal; calculating the discrete fourier transform points for the masking threshold level; computing the masker frequencies and their power levels on a frame-to-frame basis; determining a global threshold of hearing at each said masker frequency on a frame-to-frame basis; obtaining the sound pressure level for quiet, below which a signal is inaudible; inputting a covert signal; digitizing said covert signal; modifying the amplitude of said power spectrum of said host signal by embedding therein said digitized said covert signal on a frame-by-frame basis; inverting the frequency spectrum of said amplitude-modified said power spectrum; obtaining time domain samples for said inverted frequency spectrum; quantizing said time domain samples; transmitting said time domain samples; receiving at a receiver each quantized bit of each said frame of said time domain-sampled said inverted frequency spectrum; processing said each quantized bit to obtain said masking threshold; and recovering data from said embedded said covert signal; wherein said step of determining a global threshold of hearing further comprises the step of computing T Q ( f ) = 3.64 ( f 1000 ) - 0.8 - 6.5 e - 0.6 ( f 1000 - 33 ) 2 + 10 - 3 ( f 1000 ) 4 at each said masker frequency.
Claim 2
Independent Claim
237 words
A method for embedding data in audio signals by altering the amplitude of a host signal audio power spectrum, comprising the steps of: inputting a host signal; calculating the discrete fourier transform points for the masking threshold level; computing the masker frequencies and their power levels on a frame-to-frame basis; determining a global threshold of hearing at each said masker frequency on a frame-to-frame basis; obtaining the sound pressure level for quiet, below which a signal is inaudible; inputting a covert signal; digitizing said covert signal; modifying the amplitude of said power spectrum of said host signal by embedding therein said digitized said covert signal on a frame-by-frame basis; inverting the frequency spectrum of said amplitude-modified said power spectrum; obtaining time domain samples for said inverted frequency spectrum; quantizing said time domain samples; transmitting said time domain samples; receiving at a receiver each quantized bit of each said frame of said time domain-sampled said inverted frequency spectrum; processing said each quantized bit to obtain said masking threshold; and recovering data from said embedded said covert signal; wherein said step of determining a global threshold of hearing further comprises the step of computing T Q ( f ) = 3.64 ( f 1000 ) - 0.8 - 6.5 e - 0.6 ( f 1000 - 33 ) 2 + 10 - 3 ( f 1000 ) 4 at each said masker frequency.
Claim 3
Dependent Claim
81 words
Method of claim 1 ,wherein said step of modifying the amplitude of said power spectrum further comprises modifying said discrete fourier transform points of said power spectrum P(k) to P′(k) by the rule: P ′ ( k ) ≈ { 0.3 T G ( k ) , if b ( k ) = 0 0.7 T G ( k ) , if b ( k ) = 1 } .
Claim 4
Dependent Claim
82 words
Method of claim 1 , wherein said step of recovering data further comprises the step de-embedding said data by the rule: d ( k ) = { 0 , 0.2 T g ( n ) < P r ( n ) < 0.4 T g ( n ) 1 , 0.6 T g ( n ) < P r ( n ) < 0.8 T g ( n ) } .
Claim 5
Independent Claim
199 words
A method for embedding data in audio signals by altering the phase spectrum of a host signal, comprising the steps of: inputting a host signal; calculating the perceptually masked discrete fourier transform points; inputting a covert signal; digitizing said covert signal; modifying the phase of said phase spectrum by embedding therein said digitized said covert signal on a frame-by-frame basis; inverting said phase-modified said phase spectrum; obtaining time domain samples for said inverted said phase-modified spectrum; quantizing said time domain samples; transmitting said time domain samples; receiving at a receiver each quantized bit of each said frame of said time domain-sampled said inverted phase spectrum; processing said each quantized bit to obtain said masking threshold and to recover said phase; and recovering data from said embedded said covert signal; wherein said step of modifying the phase of said phase spectrum further comprises modifying said discrete Fourier transform points of said phase spectrum φ(k) to φ′(k) by the rule φ ′ ( k ) ≈ { + θ , if b ( k ) = 0 - θ , if b ( k ) = 1 } , at {k} such that T q (k)<(k)<T G (k)−5.
Claim 6
Independent Claim
199 words
A method for embedding data in audio signals by altering the phase spectrum of a host signal, comprising the steps of: inputting a host signal; calculating the perceptually masked discrete fourier transform points; inputting a covert signal; digitizing said covert signal; modifying the phase of said phase spectrum by embedding therein said digitized said covert signal on a frame-by-frame basis; inverting said phase-modified said phase spectrum; obtaining time domain samples for said inverted said phase-modified spectrum; quantizing said time domain samples; transmitting said time domain samples; receiving at a receiver each quantized bit of each said frame of said time domain-sampled said inverted phase spectrum; processing said each quantized bit to obtain said masking threshold and to recover said phase; and recovering data from said embedded said covert signal; wherein said step of modifying the phase of said phase spectrum further comprises modifying said discrete Fourier transform points of said phase spectrum φ(k) to φ′(k) by the rule φ ′ ( k ) ≈ { + θ , if b ( k ) = 0 - θ , if b ( k ) = 1 } , at {k} such that T q (k)<(k)<T G (k)−5.
Claim 7
Dependent Claim
40 words
Method of claim 4 , wherein said step of recovering data further comprises the step de-embedding said data by the rule: d ( k ) = { 0 , θ > 0 1 , θ < 0 } .
References Cited (Backward Citations)
No citation records indexed.
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