Floating point signal reversible encoding method, decoding method, device thereof, program, and recording medium thereof
First Claim
1. A lossless coding method for a signal in a floating-point format, comprising:
- (a) a step of converting a first signal sample sequence in the floating-point format into a second signal sample sequence in an integer format;
(b) a step of losslessly compressing said second signal sample sequence in the integer format to produce a first code sequence;
(c) a step of producing a difference signal in the floating-point format that corresponds to the difference between said second signal sample sequence in the integer format and said first signal sample sequence in the floating-point format;
(d) a step of determining which coding processing is of higher compression efficiency, a first coding processing that codes a bit sequence of digits capable of assuming non-zero values in each of samples of said difference signal in the floating-point format, the digits being determined by the absolute value of the corresponding sample in said second signal sample sequence in the integer format, or a second coding processing that codes all digits of said difference signal; and
(e) a step of coding said difference signal by said first coding processing to produce a second code sequence if the result of said determination indicates said first coding processing, or coding said difference signal by said second coding processing to produce a second code sequence if the result of said determination indicates said second coding processing.
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Abstract
The average amplitude of the samples in a signal sample sequence X in a floating-point format is determined for each frame. If the average amplitude is greater than a predetermined value, an integer formatting part 12 converts the sequence X into a signal sample sequence Y in a 16-bit integer format by truncation, a compressing part 13 codes the sequence Y to output a code sequence Ca, a difference producing part 14 produces a difference signal Z that corresponds to the difference between the signal sample sequence X and a sequence Y′ in the floating-point format converted from the sequence Y, and a compressing part 17performs entropy coding on the least significant (23−n) bits of a mantissa M of the difference signal Z, which is determined by the number of bits n following the most significant “1” in each sample in the sequence Y, and outputs a code sequence Cb. If the average amplitude is not greater than the predetermined value, the sequence X is directly losslessly coded by a compressing part 121. A code Cd, which indicates which coding is selected, is output.
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Citations
17 Claims
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1. A lossless coding method for a signal in a floating-point format, comprising:
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(a) a step of converting a first signal sample sequence in the floating-point format into a second signal sample sequence in an integer format; (b) a step of losslessly compressing said second signal sample sequence in the integer format to produce a first code sequence; (c) a step of producing a difference signal in the floating-point format that corresponds to the difference between said second signal sample sequence in the integer format and said first signal sample sequence in the floating-point format; (d) a step of determining which coding processing is of higher compression efficiency, a first coding processing that codes a bit sequence of digits capable of assuming non-zero values in each of samples of said difference signal in the floating-point format, the digits being determined by the absolute value of the corresponding sample in said second signal sample sequence in the integer format, or a second coding processing that codes all digits of said difference signal; and (e) a step of coding said difference signal by said first coding processing to produce a second code sequence if the result of said determination indicates said first coding processing, or coding said difference signal by said second coding processing to produce a second code sequence if the result of said determination indicates said second coding processing. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10)
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2. A lossless coding method for a signal in a floating-point format, comprising:
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(a) a step of determining, on a frame basis, which compression is of higher compression efficiency, a direct lossless compression of a first signal sample sequence in the floating-point format on a frame basis or a dual-signal separate compression of an integer-value sample sequence and a difference signal; (b) a step of performing the dual-signal separate compression if the result of said determination indicates the dual-signal separate compression, the step (b) comprising; (b-1) a step of converting the first signal sample sequence into a second signal sample sequence in an integer format; (b-2) a step of losslessly compressing said second signal sample sequence in the integer format to produce a first code sequence; (b-3) a step of producing a difference signal in the floating-point format that corresponds to the difference between said second signal sample sequence in the integer format and said first signal sample sequence in the floating-point format; (b-4) a step of producing a second code sequence from said difference signal in the floating-point format; (c) a step of directly losslessly compressing said first signal sample sequence to produce a third code sequence if the result of said determination indicates the direct lossless compression; and (d) a step of producing an auxiliary code that indicates whether said direct lossless compression or said dual-signal separate compression is performed, wherein, in said step (b-1), the conversion into said second signal sample sequence in the integer format is achieved by truncation of a fractional part, and said step (b-4) comprises; (b-4-1) a step of determining which coding processing is of higher compression efficiency, a first coding processing that codes a bit sequence of digits capable of assuming non-zero values in each of samples of said difference signal in the floating-point format, the digits being determined by the absolute value of the corresponding sample in said second signal sample sequence in the integer format, or a second coding processing that codes all digits of said difference signal; and (b-4-2) a step of coding said difference signal by said first coding processing to produce a second code sequence if the result of said determination indicates said first coding processing, or coding said difference signal by said second coding processing to produce a second code sequence if the result of said determination indicates said second coding processing.
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11. A lossless decoding method for a signal in a floating-point format, comprising:
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(a) a step of determining whether an input code sequence is a code sequence produced by a single-signal coding or a dual-signal coding, based on an input auxiliary code; and (b) if the result of said determination indicates the single-signal coding, a step of decoding and expanding an input code sequence as one code sequence to reproduce an original signal sample sequence in the floating-point format; (c) if the result of said determination indicates the dual-signal coding, a step of separating the input code sequence into a first code sequence and a second code sequence; (d) a step of decoding and expanding said first code sequence to produce a first signal sample sequence in an integer format; (e) a step of deriving a difference signal in the floating-point format from said second code sequence; (f) a step of converting said first signal sample sequence in the integer format into a second signal sample sequence in the floating-point format; and (g) a step of combining said second signal sample sequence in the floating-point format and said difference signal in the floating-point format to produce the original signal sample sequence in the floating-point format, wherein said step (e) comprises; a step of determining which of a first expansion method and a second expansion method is used to decode and expand said second code sequence, based on said first signal sample sequence in the integer format or the input auxiliary code; and a step of decoding and expanding said second code sequence into bit sequences each containing a number of digits capable of assuming non-zero values, the number of digits being uniquely determined by the absolute value of each sample of said first signal sample sequence, and assembling said difference signal from the bit sequences resulting from the decoding and expansion if the result of the determination indicates the first expansion method, or a step of directly decoding and expanding said second code sequence into said difference signal by the second expansion method if the result of the determination indicates the second expansion method. - View Dependent Claims (13, 14, 15)
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12. A lossless decoding method for a signal in a floating-point format, comprising:
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(a) a step of decoding and expanding a first code sequence to produce a first signal sample sequence in an integer format; (b) a step of determining which of a first expansion method and a second expansion method is used to decode and expand a second code sequence, based on said first signal sample sequence or an auxiliary code; (c) if the result of the determination indicates the first expansion method, a step of decoding and expanding said second code sequence into bit sequences each containing digits capable of assuming non-zero values, said digits being uniquely determined by the absolute value of the corresponding sample in said first signal sample sequence, and assembling the bit sequences resulting from the decoding and expansion into a difference signal in the floating-point format; (d) if the result of the determination indicates the second expansion method, a step of producing all digits of a difference signal in the floating-point format from said second code sequence; (e) a step of converting said first signal sample sequence in the integer format into a second signal sample sequence in the floating-point format; and (f) a step of combining said first signal sample sequence in the floating-point format and said difference signal in the floating-point format to reproduce an original digital signal sequence in the floating-point format.
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16. A lossless coder for a signal in a floating-point format, comprising:
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a first coding part that converts an input first signal sample sequence in the floating-point format into a second signal sample sequence in an integer format and losslessly compresses the second signal sample sequence; a difference producing part that produces a difference signal in the floating-point format that corresponds to the difference between said second signal sample sequence in the integer format and said first signal sample in the floating-point format; a second coding part that codes all digits of said difference signal in the floating-point format; a third coding part that codes a bit sequence of digits capable of assuming non-zero values in each sample of said difference signal, said digits being determined by the absolute value of the corresponding sample in said signal sample sequence in the integer format; and means for determining or estimating which of said second coding part and said third coding part provides higher compression efficiency, and selecting and outputting the code from the coding part determined or estimated to provide higher compression efficiency.
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17. A decoder for a signal in a floating-point format, comprising:
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a first expanding part that decodes and expands an input first code sequence to produce a first signal sample sequence in an integer format; a second expanding part that decodes and expands an input second code sequence in a difference signal into a bit sequence containing digits capable of assuming non-zero values, said digits being determined by the absolute value of the corresponding sample in said first signal sample sequence in the integer format, and assembles the bits sequences resulting from the decoding and expansion into a difference signal in the floating-point format; a third expanding part that directly decodes and expands said input second code sequence into all digits of said difference signal in the floating-point format; a selecting part that selects one of said second expanding part and said third expanding part based on said first signal sample sequence or an input auxiliary code; and a combining part that combines said first signal sample sequence in the floating-point format and said difference signal in the floating-point format received from the selected one of said second expanding part and the third expanding part to produce a third signal sample sequence in the floating-point format.
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Specification