US5945932A
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Technique for embedding a code in an audio signal and for detecting the embedded code
Assignee: Audiotrack Corp
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Filing: 1997-10-30
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Granted: 1999-08-31
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Expires: 2017-10-30
Abstract
Abstract A code is embedded into an audio product so as to be processed therewith for recording and/or broadcast and yet be reliably detected while remaining inaudible to human perception. The code is represented by symbols formed from an impulse function having its energy within a specified frequency range. The audio product is analyzed to find segments which can mask the code based on tonality and a minimum signal energy. When the audio product with an embedded code is detected, decoding thereof involves finding candidate code signals which are checked against preset criteria. In particular, each symbol is made of at least two impulse functions with a preset spacing therebetween.
Inventors
- 👤 Gregory L. Smith
- 👤 John H. D. Wiltshire
- 👤 Marvin C. Nolan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 12:16
CPC Classifications
G; G10; G10L; G10L19/00; G10L19/018; H; H04; H04B; H04B1/00; H04B1/66; H04B1/665; G11; G11B; G11B20/00; G11B20/00086; G11B20/00884; G11B20/00891
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
99 words
A method for embedding a digital code in a digitized audio product, comprising the steps of: filtering the digitized audio product to a frequency band of interest; determining a tonality indication for each of a plurality of segments of the filtered audio product which indicates the extent to which power is distributed uniformly for frequencies in at least a portion of said band of interest; and inserting at least a portion of the digital code into a particular segment from said plurality of segments only if said tonality indication indicates a relatively uniform power distribution in said particular segment.
Claim 2
Independent Claim
99 words
A method for embedding a digital code in a digitized audio product, comprising the steps of: filtering the digitized audio product to a frequency band of interest; determining a tonality indication for each of a plurality of segments of the filtered audio product which indicates the extent to which power is distributed uniformly for frequencies in at least a portion of said band of interest; and inserting at least a portion of the digital code into a particular segment from said plurality of segments only if said tonality indication indicates a relatively uniform power distribution in said particular segment.
Claim 3
Dependent Claim
39 words
The method of claim 1, wherein said inserting step is performed only if at least one of the segments immediately before and immediately after said particular segment also has a tonality indication which indicates a relatively uniform power distribution.
Claim 4
Dependent Claim
16 words
The method of claim 1, wherein all of said plurality of segments have a uniform duration.
Claim 5
Dependent Claim
35 words
The method of claim 1, further comprising the step of determining the total power for at least said particular segment, and performing said inserting step only if said total power is above a predetermined threshold.
Claim 6
Independent Claim
76 words
A method for embedding a digitized code in a digitized audio product, comprising the steps of: filtering the digitized audio product to a frequency band of interest; providing a coding signal derived from a band-limited impulse function with a waveform having its energy confined to and evenly spread across at least a portion of said frequency band of interest; deriving said digitized code from said coding signal; and embedding said digitized code into said audio product.
Claim 7
Independent Claim
76 words
A method for embedding a digitized code in a digitized audio product, comprising the steps of: filtering the digitized audio product to a frequency band of interest; providing a coding signal derived from a band-limited impulse function with a waveform having its energy confined to and evenly spread across at least a portion of said frequency band of interest; deriving said digitized code from said coding signal; and embedding said digitized code into said audio product.
Claim 8
Dependent Claim
30 words
The method of claim 5, wherein said frequency band of interest is approximately 0 to 5000 Hz, and said coding signal has energy spread across approximately 1500 to 4000 Hz.
Claim 9
Dependent Claim
18 words
The method of claim 5, wherein said digitized code is derived based on polarity of said coding signal.
Claim 10
Dependent Claim
22 words
The method of claim 5, wherein each bit of said digitized code is derived based on a plurality of said coding signals.
Claim 11
Dependent Claim
25 words
The method of claim 5, wherein said coding signal is derived from an ideal mathematical impulse function to which a steep bandpass filter is applied.
Claim 12
Independent Claim
76 words
A method for providing a digitized code to be embedded in a digitized audio product, comprising the steps of: providing said digitized code as a series of binary bits; dividing said binary bits into groups, each group having a plurality of bits; providing coding signals to represent said bits, respectively; deriving a symbol from said coding signals for each of said groups, each symbol having a plurality of said coding signals with a preset spacing therebetween.
Claim 13
Independent Claim
76 words
A method for providing a digitized code to be embedded in a digitized audio product, comprising the steps of: providing said digitized code as a series of binary bits; dividing said binary bits into groups, each group having a plurality of bits; providing coding signals to represent said bits, respectively; deriving a symbol from said coding signals for each of said groups, each symbol having a plurality of said coding signals with a preset spacing therebetween.
Claim 14
Dependent Claim
24 words
The method of claim 10, wherein each symbol has coding signals equal in number to bits in a group to which such symbol corresponds.
Claim 15
Dependent Claim
41 words
The method of claim 10, wherein the coding signals are identical to each other in shape, with one binary bit corresponding to a coding signal of one polarity, and the other binary bit corresponding to a signal of the other polarity.
Claim 16
Dependent Claim
15 words
The method of claim 10, wherein a symbol consists of two of said coding signals.
Claim 17
Dependent Claim
21 words
The method of claim 10, wherein a symbol consists of three of said coding signals with equal spacing between adjacent ones.
Claim 18
Independent Claim
136 words
A method for encoding and decoding a digitized code embedded in a digitized audio product, comprising the steps of: deriving said digitized code in a form of start, data and end symbol types, each symbol representing a plurality of bits, and each bit being associated with a coding signal of given polarity; generating said start type of symbol to consist of a plurality of said coding signals all of which have the same designated polarity; embedding said digitized code in said digitized audio product; detecting said digitized code embedded in said audio product; and decoding said detected digitized code by determining whether the polarity of the coding signals on said start type of symbol is said designated polarity and, if not, inverting the polarity of said coding signals in said data and end types of symbols.
Claim 19
Independent Claim
136 words
A method for encoding and decoding a digitized code embedded in a digitized audio product, comprising the steps of: deriving said digitized code in a form of start, data and end symbol types, each symbol representing a plurality of bits, and each bit being associated with a coding signal of given polarity; generating said start type of symbol to consist of a plurality of said coding signals all of which have the same designated polarity; embedding said digitized code in said digitized audio product; detecting said digitized code embedded in said audio product; and decoding said detected digitized code by determining whether the polarity of the coding signals on said start type of symbol is said designated polarity and, if not, inverting the polarity of said coding signals in said data and end types of symbols.
Claim 20
Independent Claim
81 words
A method for embedding a digitized code in a digitized audio product, comprising the steps of: identifying segments of the digitized audio product into which the digitized code can be embedded based on predetermined criteria; generating portions of the digitized code for insertion into said segments, respectively; removing the digitized audio product within said identified segments except for a predetermined small percentage of amplitude to generate modified segments; and inserting said portions of the digitized code into said modified segments, respectively.
Claim 21
Independent Claim
81 words
A method for embedding a digitized code in a digitized audio product, comprising the steps of: identifying segments of the digitized audio product into which the digitized code can be embedded based on predetermined criteria; generating portions of the digitized code for insertion into said segments, respectively; removing the digitized audio product within said identified segments except for a predetermined small percentage of amplitude to generate modified segments; and inserting said portions of the digitized code into said modified segments, respectively.
Claim 22
Independent Claim
112 words
A method for embedding a digitized code in a digitized audio product, comprising the steps of: analyzing the digitized audio product to derive measured values for designated characteristics thereof; locating segments of the digitized audio product, based on said derived measured values and a set of preselected parameters, into which the digitized code can be inserted so as to be masked; inserting the digitized code into said located segments; determining whether a degree of masking of the inserted digitized code meets a predetermined level and, if not, modifying values of at least one of said set of preselected parameters, and then performing said locating and inserting steps again with said modified values.
Claim 23
Independent Claim
112 words
A method for embedding a digitized code in a digitized audio product, comprising the steps of: analyzing the digitized audio product to derive measured values for designated characteristics thereof; locating segments of the digitized audio product, based on said derived measured values and a set of preselected parameters, into which the digitized code can be inserted so as to be masked; inserting the digitized code into said located segments; determining whether a degree of masking of the inserted digitized code meets a predetermined level and, if not, modifying values of at least one of said set of preselected parameters, and then performing said locating and inserting steps again with said modified values.
Claim 24
Independent Claim
77 words
A method for embedding a digitized code in an audio product, comprising the steps of: dividing said digitized code into preselected portions; representing said portions by a plurality of coding symbols, respectively; determining spacing of said coding symbols from each other to be used for embedding the digitized code within the audio product so that said spacing is greater than a predetermined minimum, and inserting the coding symbols within the audio product based on said determined spacing.
Claim 25
Independent Claim
77 words
A method for embedding a digitized code in an audio product, comprising the steps of: dividing said digitized code into preselected portions; representing said portions by a plurality of coding symbols, respectively; determining spacing of said coding symbols from each other to be used for embedding the digitized code within the audio product so that said spacing is greater than a predetermined minimum, and inserting the coding symbols within the audio product based on said determined spacing.
Claim 26
Dependent Claim
24 words
The method of claim 18, wherein said predetermined minimum spacing for a present symbol is in relation to a location of a previous symbol.
Claim 27
Dependent Claim
27 words
The method of claim 18, wherein said predetermined minimum spacing for a present symbol is in relation to a location of the immediately preceeding previous two symbols.
Claim 28
Dependent Claim
15 words
The method of claim 18, wherein said spacing is derived to produce a random spacing.
Claim 29
Independent Claim
82 words
A method for decoding an audio product into which a code of digitized coding signals has been embedded, comprising the steps of: obtaining a digitized audio product; comparing said digitized audio product with a template of a coding signal to identify candidate coding signals based on shape; comparing pairs of sequential candidate coding signals with each other based on preselected characteristics to identify which ones constitute the coding signals; and reconstructing said code from said coding signals identified by said comparing step.
Claim 30
Independent Claim
82 words
A method for decoding an audio product into which a code of digitized coding signals has been embedded, comprising the steps of: obtaining a digitized audio product; comparing said digitized audio product with a template of a coding signal to identify candidate coding signals based on shape; comparing pairs of sequential candidate coding signals with each other based on preselected characteristics to identify which ones constitute the coding signals; and reconstructing said code from said coding signals identified by said comparing step.
Claim 31
Dependent Claim
11 words
The method of claim 22, wherein said comparing step compares amplitude.
Claim 32
Dependent Claim
24 words
The method of claim 22, wherein said comparing step compares a predetermined spacing with spacing between a sequential pair of said candidate coding signals.
References Cited (Backward Citations)
US5796785A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2002-08-30 | 2003-03-01 | 2003-08-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-08-30 | 2007-03-01 | 2007-08-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-08-30 | 2011-03-01 | 2011-08-31 | $7700.00 | Window Closed / Lapsed |