EP0118771A2
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Compression and expansion of digitized voice signals
Assignee: Intel Corp
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Filing: 1984-02-09
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Granted: —
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Expires: 2004-02-09
Abstract
Abstract Apparatus and a method are disclosed for digitizing a voice signal as it occurs and the digitized signal is compressed and stored for subsequent reconversion to a voice signal at a latter time. Binary words derived from digitizing the signal in an analog-to-digital converter represent the voice non lineary and are first linearized by a first processor and then stored in a first memory until a block of binary words are assembled. Next the block of binary words are transferred to a second buffer memory and a second processor compresses it using time domain harmonic scaling processing which extracts the pitch of the original voice and also compresses the voice frequency spectrum to affect a 2:1 reduction in the number of stored binary words representing the digitized voice signal. This reduced amout of data is then upsampled by a factor of four using linear interpolation to derive a pseudo higher sample rate required for further processing using continuously variable slope delta modulation processing which yields one binary bit out for every binary word processed. The resultant bits are assembled into eight bit words and then stored in a third memory. Another binary word representing the pitch is added and the result is a 4:1 compression of the original digitized data. The compressed digitized data is stored in a bulk memory. Thereafter, more digitized samples of the voice signal undergo this same processing. Compressed digitized voice signals may be reconverted to a voice signal for playback by processing the digitized and compressed voice signals generally in the reverse order. Playback speed control may also be accomplished without changing the pitch of the voice. To double the playback speed the time domain harmonic scaling processing is deleted in playback, thus leaving the frequency spectrum compressed and a 2:1 reduction in binary words representing the digitized voice. To slow the playback speed the digitized voice signals undergo modified TDHS processing.
Inventors
- 👤 Lawrence Edmond Bergeron
- 👤 Daniel Francis Daly
- 👤 Elaine Chipouras Grosso
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 23:14
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/66; G; G10; G10L; G10L21/00; G10L21/04
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
167 words
1 . A method for compressing a first number of binary words representing a continuously varying signal over a given period of time where said varying signal has been sampled at a predetermined rate per unit time and the samples digitized to said first number of binary words, with the varying signal having a pitch value, and comprising the steps of: extracting the pitch value of said varying signal from said first number of binary words and indicating the pitch value by a binary number, reducing said first number of binary words using a first signal processing technique to a second number of binary words, and processing said second number of binary words using a second signal processing technique that processes binary words representing sample points of said varying signal to encode each of said second number of binary words as a binary bit representing the slope of said varying - signal, to thereby reduce said second number of binary words to a number of binary bits.
Claim 2
Dependent Claim
167 words
1 . A method for compressing a first number of binary words representing a continuously varying signal over a given period of time where said varying signal has been sampled at a predetermined rate per unit time and the samples digitized to said first number of binary words, with the varying signal having a pitch value, and comprising the steps of: extracting the pitch value of said varying signal from said first number of binary words and indicating the pitch value by a binary number, reducing said first number of binary words using a first signal processing technique to a second number of binary words, and processing said second number of binary words using a second signal processing technique that processes binary words representing sample points of said varying signal to encode each of said second number of binary words as a binary bit representing the slope of said varying - signal, to thereby reduce said second number of binary words to a number of binary bits.
Claim 3
Dependent Claim
69 words
The method in accordance with claim 1 further comprising the step of: assembling the bits provided per said second signal processing technique into multi bit binary words, said multi bit binary words and said binary word representing said pitch value representing said continuously varying signal and being compressed substantially in the order of four to one in comparison to said first number of binary words representing said varying signal.
Claim 4
Dependent Claim
52 words
The method in accordance with claim 2 further comprising the step of increasing said second number of binary words resulting from said first signal processing technique by interpolating between each of said second number of binary words-because said second number of binary words are insufficient for proper processing using said processing step.
Claim 5
Independent Claim
137 words
A method for digitizing a continuously variable signal and reducing the number of binary words obtained from the digitization comprising the steps of: digitizing said varying signal to obtain a first number of binary words representing said varying signal over a given period of time, extracting the pitch value of said varying signal from said first number of binary words and indicating same by a binary number, reducing said first number of binary words using a first signal processing technique to a second number of binary words, and processing said second number of binary words using a second signal processing technique that processes binary words representing sample points of a varying signal to encode each of said second number of binary words to reduce each of said second number of binary words to a smaller binary representation.
Claim 6
Independent Claim
137 words
A method for digitizing a continuously variable signal and reducing the number of binary words obtained from the digitization comprising the steps of: digitizing said varying signal to obtain a first number of binary words representing said varying signal over a given period of time, extracting the pitch value of said varying signal from said first number of binary words and indicating same by a binary number, reducing said first number of binary words using a first signal processing technique to a second number of binary words, and processing said second number of binary words using a second signal processing technique that processes binary words representing sample points of a varying signal to encode each of said second number of binary words to reduce each of said second number of binary words to a smaller binary representation.
Claim 7
Dependent Claim
67 words
The method in accordance with claim 4 wherein said digitizing step comprises the steps of: sampling said varying signal at a plurality of points and generating a binary number for each sample; and processing each binary number from the sampling step and changing each binary number as necessary to correct for non linearities inherent in the sampling step, and thereby generate said first number of binary words.
Claim 8
Dependent Claim
69 words
The method in accordance with claim 5 further comprising the step of assembling the smaller binary representations provided per said second signal processing technique into larger binary words, said larger binary words and said binary word representing said pitch value representing said continuously varying signal but being compressed substantially in the order of four to one in comparison to said first number of binary words representing said varying signal.
Claim 9
Dependent Claim
51 words
The method in accordance with claim 5 further comprising the step of: increasing said second number of binary words resulting from said reducing step by interpolating between pairs of said second number of binary words because said second number of binary words are insufficient for proper processing using said processing step.
Claim 10
Dependent Claim
39 words
The method in accordance with claim 6 further comprising the step of assembly said first binary numbers obtained in digitizing said continuously varying signal into blocks of binary numbers upon which said pitch extracting and reducing steps are performed.
Claim 11
Independent Claim
190 words
A method for accomplishing playback speed control in a system that digitizes a continuously varying signal into a first number of binary words and then utilizes a signal processing technique that utilizes said first number of binary words to derive the pitch of the varying signal and represents it as a binary word and also reduces the first number of binary words to a second number of binary words also representing said varying signal, and playback of said varying signal.is accomplished by processing said second number of binary words and said pitch binary number in an inverse manner using said signal processing technique to derive said first number of binary words which are then reconverted to said varying signal by digital to analog conversion, comprising the step of: modifying said signal processing technique for playback to expand each second binary word into a plurality of binary words different than said first nunber of binary words and when said plurality of binary words are converted into said continuously varying signal the speed of playback of said varying signal is different than the speed of the origonal varying signal that was digitized.
Claim 12
Independent Claim
190 words
A method for accomplishing playback speed control in a system that digitizes a continuously varying signal into a first number of binary words and then utilizes a signal processing technique that utilizes said first number of binary words to derive the pitch of the varying signal and represents it as a binary word and also reduces the first number of binary words to a second number of binary words also representing said varying signal, and playback of said varying signal.is accomplished by processing said second number of binary words and said pitch binary number in an inverse manner using said signal processing technique to derive said first number of binary words which are then reconverted to said varying signal by digital to analog conversion, comprising the step of: modifying said signal processing technique for playback to expand each second binary word into a plurality of binary words different than said first nunber of binary words and when said plurality of binary words are converted into said continuously varying signal the speed of playback of said varying signal is different than the speed of the origonal varying signal that was digitized.
Claim 13
Dependent Claim
50 words
The method in accordance with claim 9 further comprising the step of decreasing said second number of binary numbers to a reduced number of binary words by deleting periodic ones of same, said reduced number of binary words then being processed by said signal processing technique in an inverse manner.
Claim 14
Independent Claim
166 words
A method for accomplishing playback speed control in a system that digitizes a continuously varying signal into a first number of binary words and then utilizes a signal processing technique that utilizes said first number of binary words to derive the pitch of the varying signal and represents it as a binary word and also reduces the first number of binary words to a second number of binary words also representing said varying signal, and playback of said varying signal is accomplished by processing said second number of binary words and said pitch binary number in an inverse manner using said signal processing technique to derive said first number of binary words which are then reconverted to said varying signal by digital to analog conversion, comprising the step of: applying said second number of binary words directly to said digital to analog conversion to increase the playback speed which is doubled when said second number of binary words is half the first number of binary words.
Claim 15
Independent Claim
166 words
A method for accomplishing playback speed control in a system that digitizes a continuously varying signal into a first number of binary words and then utilizes a signal processing technique that utilizes said first number of binary words to derive the pitch of the varying signal and represents it as a binary word and also reduces the first number of binary words to a second number of binary words also representing said varying signal, and playback of said varying signal is accomplished by processing said second number of binary words and said pitch binary number in an inverse manner using said signal processing technique to derive said first number of binary words which are then reconverted to said varying signal by digital to analog conversion, comprising the step of: applying said second number of binary words directly to said digital to analog conversion to increase the playback speed which is doubled when said second number of binary words is half the first number of binary words.
Claim 16
Dependent Claim
55 words
The method in accordance with claim 11 wherein said continuously varying signal is played back at the same speed it was originally when digitized when said second number of binary words is converted to said first number of binary - words by inverse processing using said signal processing technique and further comprising the step of:
Claim 17
Dependent Claim
50 words
The method in accordance with claim 12 further comprising the step of decreasing said second number of binary numbers to a reduced number of binary words by deleting periodic ones of same, said reduced number of binary words then being processed by said signal processing technique in an inverse manner.
References Cited (Backward Citations)
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