EP0570131A1
Expired / Lapsed
EP
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Compression encoding and decoding of digital audio signals
Assignee: Sony Corp
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Filing: 1993-04-28
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Granted: —
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Expires: 2013-04-28
Abstract
Abstract A method for compression encoding of digital speech signals is provided in which the digital speech signals are divided at a predetermined time interval into plural frequency bands so as to be sub-divided along both the time scale and the frequency scale to form plural sub-blocks, and data encoding is performed using an allocation bit number determined for each of said sub-blocks. The total number of bits that may be used for bit allocation is divided into at least two portions, with the bits of one of theses portions being allocated in dependence upon the allowable noise level based on aural characteristics and with the bits of the remaining portion being allocated in dependence upon the intensities of signals in each sub-block. The number of bits allocated to each of the small-sized sub-blocks are determined by the sum of the bits of the two portions. In addition to the total number of bits that may be used for bit allocation, a number of bits can also be set for the subsidiary information at least including the floating information and the bit length information. The aural characteristics may be combined from at least the masking threshold and the minimum audibility curve and corrected by the equal-loudness curve.
Inventors
- 👤 Kenzo C/O Patents Division Akagiri
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 23:50
CPC Classifications
G; G10; G10L; G10L19/00; G10L19/002; G10L19/02; G10L19/0204; G10L19/0208; G10L19/005; H; H04; H04B; H04B1/00; H04B1/66; H04B1/665
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
154 words
A method for bit allocation in compression encoding of digital speech signals in which the digital speech signals are divided at a predetermined time interval into plural frequency bands so as to be sub-divided along both the time scale and the frequency scale to form plural sub-blocks and data encoding is performed using an allocation bit number determined for each of said sub-blocks, the method comprising: dividing the total number of bits that may be used for bit allocation into at least two portions; allocating bits of one of said portions in dependence upon an allowable noise spectrum based on aural characteristics; allocating bits of the remaining portion in dependence upon signal intensities in each of said sub-blocks sub-divided along both the time scale and the frequency scale; and combining the bits of said two portions together for each of said sub-blocks to decide the number of bits allocated to each of said sub-blocks.
Claim 2
Dependent Claim
31 words
A method as claimed in claim 1, wherein the number of bits allocated to subsidiary information is set, said subsidiary information being at least the floating information and bit length information.
Claim 3
Dependent Claim
25 words
A method as claimed in claim 1 or claim 2, wherein said aural characteristics comprise at least a masking threshold and a minimum audibility curve.
Claim 4
Dependent Claim
31 words
A method as claimed in claim 1 or claim 2, wherein said aural characteristics comprise at least a masking threshold and a minimum audibility curve and corrected by an equal-loudness curve.
Claim 5
Independent Claim
45 words
A method as claimed in any preceding claim, wherein the signal intensities in each of said sub-blocks sub-divided along both the time scale and the frequency scale are signal energies in said sub-blocks represented by a root-mean-square value of amplitudes in each of said sub-blocks.
Claim 6
Independent Claim
61 words
A method as claimed in any preceding claim, wherein bit allocation is effected such that the number of bits allocated in dependence upon the allowable noise spectrum based on said aural characteristics is larger than the number of bits allocated in dependence upon the signal intensities in each of the sub-blocks sub-divided along both the time scale and the frequency scale.
Claim 7
Independent Claim
55 words
A method as claimed in any one of claims 1 to 3, wherein said sub-blocks are obtained by subdivision along the time scale into a low-range spectral portion, a mid-range spectral portion and a high-range spectral portion, and by subdivision along the frequency scale at least in part into frequency bands coincident with critical bands.
Claim 8
Dependent Claim
166 words
A recording medium having data recorded thereon, said data being formed by a method for bit allocation in compression encoding of digital speech signals in which the digital speech signals are divided at a predetermined time interval into plural frequency bands so as to be sub-divided along both the time scale and the frequency scale to form plural sub-blocks and data encoding is performed using an allocation bit number determined for each of said sub-blocks, the method comprising: dividing the total number of bits that may be used for bit allocation into at least two portions; allocating bits of one of said portions in dependence upon an allowable noise spectrum based on aural characteristics; allocating bits of the remaining portion in dependence upon signal intensities in each of said sub-blocks sub-divided along both the time scale and the frequency scale; and combining the bits of said two portions together for each of said sub-blocks to decide the number of bits allocated to each of said sub-blocks.
Claim 9
Independent Claim
162 words
A device for bit allocation in compression encoding of digital speech signals in which the digital speech signals are divided at a predetermined time interval into plural frequency bands so as to be sub-divided along both the time scale and the frequency scale to form plural sub-blocks and data encoding is performed using an allocation bit number determined for each of said sub-blocks, the device comprising: means for dividing the total number of bits that may be used for bit allocation into at least two portions; means for allocating bits of one of said portions in dependence upon an allowable noise spectrum based on aural characteristics; means for allocating bits of the remaining portion in dependence upon signal intensities in each of said sub-blocks sub-divided along both the time scale and the frequency scale; and means for combining the bits of said two portions together for each of said sub-blocks to decide the number of bits allocated to each of said sub-blocks.
Claim 10
Dependent Claim
57 words
A device as claimed in claim 9, wherein said aural characteristics are supplied from aural characteristics generating means comprising masking threshold generating means and minimum audibility curve generating means, said aural characteristics generating means combining an output of said masking threshold generating means and an output of said minimum audibility curve generating means to generate aural characteristics.
Claim 11
Dependent Claim
43 words
A device as claimed in claim 9, wherein said aural characteristics generating means also include equal-loudness curve generating means for correcting a synthesized output of the output of a masking threshold generating means and an output of said minimum audibility curve generating means.
Claim 12
Dependent Claim
183 words
A recording medium having data recorded thereon, said data being formed by a method for bit allocation in compression encoding of digital speech signals in which the digital speech signals are divided at a predetermined time interval into plural frequency bands so as to be sub-divided along both the time scale and the frequency scale to form small sub-blocks and data encoding is performed using an allocation bit number determined for each of said sub-blocks, said allocation bit number being determined by a bit allocation unit comprising: means for dividing the total number of bits that may be used for bit allocation into at least two portions; means for allocating bits of one of said portions in dependence upon an allowable noise spectrum based on aural characteristics; means for allocating bits of the remaining portion in dependence upon signal intensities in each of said sub-blocks sub-divided along both the time scale and the frequency scale; and means for combining the bits of said two portions together for each of said sub-blocks to decide the number of bits allocated to each of said sub-blocks.
Claim 13
Dependent Claim
18 words
A recording medium as claimed in claim 8 or claim 12, wherein said recording medium is a disc.
Claim 14
Dependent Claim
16 words
A recording medium as claimed in claim 13, wherein said recording medium is an optical disc.
References Cited (Backward Citations)
EP0525809A2
Cited
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