United States Patent [19]
`United States Patent (19)
`Akagiri et al.
`Akagiri et al.
`
`11111111111111111111111111f111j1181!10111111111111111111111111111111
`
`USOO5873065A
`11
`Patent Number:
`5,873,065
`5,873,065
`[n] Patent Number:
`(45) Date of Patent:
`Feb. 16, 1999
`[45] Date of Patent:
`Feb. 16, 1999
`
`
`
`54 TWO-STAGE COMPRESSION AND
`[54] TWO-STAGE COMPRESSION AND
`EXPANSION OF COUPLNG PROCESSED
`EXPANSION OF COUPLING PROCESSED
`MULTI-CHANNEL SOUND SIGNALS FOR
`MULTI-CHANNEL SOUND SIGNALS FOR
`TRANSMISSION AND RECORDING
`TRANSMISSION AND RECORDING
`75 Inventors: Kenzo Akagiri, Tokyo, Japan; Mark
`[75]
`Inventors: Kenzo Akagiri, Tokyo, Japan; Mark
`Franklin Davis, Pacifica, Calif.; Craig
`Franklin Davis, Pacifica, Calif.; Craig
`Campbell Todd, Mill Valley, Calif.;
`Campbell Todd, Mill Valley, Calif.;
`Ray Milton Dolby, San Francisco,
`Ray Milton Dolby, San Francisco,
`Calif.
`Calif.
`
`73 Assignee: Sony Corporation, Tokyo, Japan
`[73] Assignee: Sony Corporation, Tokyo, Japan
`[21] Appl. No.:
`446,689
`21 Appl. No.:
`446,689
`22 PCT Filed:
`Dec. 7, 1994
`[22] PCT Filed:
`Dec. 7, 1994
`86 PCT No.:
`PCT/US94/14267
`[86] PCT No.:
`PCT/US94/14267
`S371 Date:
`Nov. 20, 1995
`§ 371 Date:
`Nov. 20, 1995
`9
`S 102(e) Date: Nov. 20, 1995
`§ 102(e) Date: Nov. 20, 1995
`O
`O
`Foreign Application Priority Data
`[30]
`Foreign Application Priority Data
`30
`Dec. 7, 1993
`JP
`Japan .................................... 5-306898
` 5-306898
`Dec. 7, 1993
`[JP]
`Japan
`6
`51
`Int. Cl. ................................ HO4S 3/00; H04B 1/66;
` H04S 3/00; H04B 1/66;
`[51] Int. C1.6
`H04H 5/00
`HO4H 5/00
`52 U.S. Cl. .............................. 7041500; 381/2; 704/227;
`[52] U.S. Cl.
` 704/500; 381/2; 704/227;
`704/229
`704/229
`[58] Field of Search
` 395/2.36, 2.38,
`58 Field of Search .................................. 395/2.36, 2.38,
`395/2.39; 381/2; 704/227, 229, 230,500
`395/2.39; 381/2; 704/227, 229, 230, 500
`
`[56]
`56)
`
`5,490,170 2/1996 Akagiri et al. .......................... 375/240
`375/240
`2/1996 Akagiri et al.
`5,490,170
`5,491,773
`2/1996 Veldhuis et al.
`395/2.38
`5,491,773 2/1996 Veldhuis et al.
`... 395/2.38
`5,535,300
`7/1996 Hall, II et al.
`395/2.36
`5. 20. Eth AI - - -
`- - - - 3.
`5,539,829
`7/1996 Lokhoff et al.
`381/2
`2- - - 2
`OKllOTTC al. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
`5,664,056 9/1997 Akagiri ................................... 704/229
`5,664,056
`9/1997 Akagiri
`704/229
`5,687,157 11/1997 Imai et al.
`369/124
`5,687,157 11/1997 Imai et al. .............................. 369/124
`Primary Examiner-David R. Hudspeth
`Primary Examiner—David R. Hudspeth
`Assistant Examiner—Talivaldis Ivars Smits
`ASSistant Examiner T?livaldis Ivars Smits
`Attorney, Agent, or Firm-Limbach & Limbach LLP
`Attorney, Agent, or Firm—Limbach & Limbach LLP
`57
`ABSTRACT
`[57]
`ABSTRACT
`A multi-channel Signal compressor for compressing digital
`A multi-channel signal compressor for compressing digital
`Sound Signals in the respective channels of a multi-channel
`sound signals in the respective channels of a multi-channel
`Sound System. The apparatus comprises a first-stage com
`sound system. The apparatus comprises a first-stage com-
`pression System and a Second-stage compression System. In
`pression system and a second-stage compression system. In
`the first-stage compression System, a coupling circuit per
`the first-stage compression system, a coupling circuit per-
`forms coupling between the digital Sound Signals of at least
`forms coupling between the digital sound signals of at least
`two of the channels to generate coupling-processed signals,
`two of the channels to generate coupling-processed signals,
`one for each of the channels. A compressor circuit receives
`one for each of the channels. A compressor circuit receives
`the coupling-processed signals from the coupling circuit and
`the coupling-processed signals from the coupling circuit and
`frequency divides each coupling-processed signal into fre
`frequency divides each coupling-processed signal into fre-
`quency range Signals in respective frequency ranges, and
`quency range signals in respective frequency ranges, and
`compresses the frequency range Signals obtained by dividing
`compresses the frequency range signals obtained by dividing
`each coupling-processed signal to generate a first-Stage
`each coupling-processed signal to generate a first-stage
`compressed signal. In the Second-stage compression System,
`compressed signal. In the second-stage compression system,
`a determining circuit receives the first-stage compressed
`a determining circuit receives the first-stage compressed
`Signal for each channel from the first-Stage compression
`signal for each channel from the first-stage compression
`System and determines an energy for each channel from the
`system and determines an energy for each channel from the
`first-stage compressed signal of the respective channel. A
`first-stage compressed signal of the respective channel. A
`channel bit apportionment decision circuit operates in
`channel bit apportionment decision circuit operates in
`References Cited
`response to the determining circuit, and apportions a prede
`References Cited
`response to the determining circuit, and apportions a prede-
`t s".
`of bits ". t that to ap
`U.S. PATENT DOCUMENTS
`termined number of bits among the channels to apportion a
`U.S. PATENT DOCUMENTS
`number of bits to each channel. Finally, an additional
`number oI DILS to eacn cnannel. Finally, an addiuona
` 341/155
`5,166,686 11/1992 Sugiyama
`compressor additionally compresses the first-stage com-
` 704/500
`5,185,800
`2/1993 Mahieux
`pressed signal of each channel using, for each channel, the
`pressed signal of each channel using, for each channel, the
`5,185,800 2/1993 Mahieux - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 704/500
`5,241,603
`8/1993 Akagiri et al.
` 704/205
`number of bits apportioned to the respective channel by the
`55. sE. E. et al. .......................... 7.
`number of bits apportioned to the respective channel by the
`5,285,498
`2/1994 Johnston
` 381/2
`5341457 S.E.4 R", al..."704s: channel bit apportionment decision circuit.
`channel bit apportionment decision circuit.
`5,341,457
`8/1994 Hall, II et al.
` 704/226
`5,471,558 11/1995 Tsutsui
` 704/219
`5,471,558 11/1995 Tsutsui ..........
`... 704/219
`5,481,614
`1/1996 Johnston ..................................... 381/2
`16 Claims, 10 Drawing Sheets
`16 Claims, 10 Drawing Sheets
`5,481,614
`1/1996 Johnston
` 381/2
`
`5,166,686 11/1992 Sugiyama - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 341/155
`
`compressor additionally compresses the first-Stage com
`
`213
`
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`
`21
`
`HULU LLC
`Exhibit 1012
`IPR2018-01170
`
`Page 1
`
`

`

`U.S. Patent
`U.S. Patent
`
`Feb. 16, 1999
`Feb. 16, 1999
`
`Sheet 1 of 10
`Sheet 1 of 10
`
`5,873,065
`5,873,065
`
`213
`213
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`
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`
`Page 2
`
`

`

`U.S. Patent
`U.S. Patent
`
`Feb. 16, 1999
`Feb. 16, 1999
`
`Sheet 2 of 10
`Sheet 2 of 10
`
`5,873,065
`5,873,065
`
`o
`
`108
`108
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`
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`
`FIG. 2
`FIG. 2
`
`Page 3
`
`

`

`U.S. Patent
`U.S. Patent
`
`Feb. 16, 1999
`Feb. 16, 1999
`
`Sheet 3 of 10
`Sheet 3 of 10
`
`5,873,065
`5,873,065
`
`- - - - - - -
`
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`
`Page 4
`
`

`

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`OI Jo 17 lamIS
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`
`ADAPTIVE BIT
`ALLOCATION AND
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`
`171
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`
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`ALLOCATION AND
`QUANTIZING
`
`Page 5
`
`

`

`U.S. Patent
`U.S. Patent
`
`Feb. 16, 1999
`Feb. 16, 1999
`
`Sheet S of 10
`Sheet 5 of 10
`
`5,873,065
`5,873,065
`
`X
`( )
`
`Z is
`
`Lll is O
`
`22 kHz
`22kHz
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`11kHz
`
`5.5kHz
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`11.6ms
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`TIME
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`FIG. 54
`
`22kHz
`22 kHz
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`11kHz
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`0
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`FIG. 5B
`FIG. 58
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`
`Page 6
`
`

`

`waled °S11
`
`OI JO 9 lamIS
`
`ao
`
`0
`
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`
`SIGNAL SPECTRUM
`DEPENDENT
`BIT ALLOCATION
`
`811
`
`806
`
`807
`
`800
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`
`FIG. 6
`
`SPECTRAL
`COEFFICIENTS
`
`801
`
`[803
`
`CALCULATION OF
`BAND
`MAGNITUDE
`
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`
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`OF SPECTRAL
`SMOOTHNESS
`
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`
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`
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`
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`
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`
`Page 7
`
`

`

`waled 'S11
`U.S. Patent
`
`01 JO L 13311S
`
`5,873,065
`
`1-530
`
`ALLOWABLE
`NOISE
`CORRECTION
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`
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`
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`
`FIG. 7
`
`Page 8
`
`

`

`U.S. Patent
`U.S. Patent
`
`Feb. 16, 1999
`Feb. 16, 1999
`
`Sheet 8 of 10
`Sheet 8 of 10
`
`5,873,065
`5,873,065
`
`N_
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`
`Page 9
`
`

`

`waled °S11
`U.S. Patent
`
`Feb. 16, 1999
`6661 '91 'glad
`
`Sheet 9 of 10
`OI JO 6 WIN
`
`5,873,065
`
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`
`Page 10
`
`

`

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`QUANTIZER
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`SECOND STAGE
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`FIG. .10
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`FIRST STAGE EXPANDER
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`SUBSIDIARY
`INFORMATION
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`SUBSIDIARY
`INFORMATION
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`5,873,065
`5,873,065
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`1
`1
`TWO-STAGE COMPRESSION AND
`TWO-STAGE COMPRESSION AND
`EXPANSION OF COUPLING PROCESSED
`EXPANSION OF COUPLING PROCESSED
`MULTI-CHANNEL SOUND SIGNALS FOR
`MULTI-CHANNEL SOUND SIGNALS FOR
`TRANSMISSION AND RECORDING
`TRANSMISSION AND RECORDING
`
`FIELD OF THE INVENTION
`FIELD OF THE INVENTION
`This invention relates to a method and apparatus for
`This invention relates to a method and apparatus for
`compressing the Sound Signals of the multi-channel Sound
`compressing the sound signals of the multi-channel sound
`System of, for example, a motion picture theater, a Video tape
`system of, for example, a motion picture theater, a video tape
`recorder, or a Video disc player, a method for transmitting
`recorder, or a video disc player, a method for transmitting
`the compressed Sound Signals of a multi-channel Sound
`the compressed sound signals of a multi-channel sound
`System, a method and apparatus for expanding the com
`system, a method and apparatus for expanding the com-
`pressed Sound Signals of a multi-channel Sound System, and
`pressed sound signals of a multi-channel sound system, and
`a recording medium on which the compressed Sound Signals
`a recording medium on which the compressed sound signals
`of a multi-channel Sound System are recorded.
`of a multi-channel sound system are recorded.
`BACKGROUND OF THE INVENTION
`BACKGROUND OF THE INVENTION
`Many techniques for compressing digital audio or speech
`Many techniques for compressing digital audio or speech
`Signals are known. For example, in Sub-band coding, a non
`signals are known. For example, in sub-band coding, a non
`block-forming frequency band dividing System, in which the
`block-forming frequency band dividing system, in which the
`input audio Signal is not divided in time into blocks, but is
`input audio signal is not divided in time into blocks, but is
`divided in frequency by a filter into plural frequency bands
`divided in frequency by a filter into plural frequency bands
`for quantizing. In a block-forming frequency band dividing
`for quantizing. In a block-forming frequency band dividing
`System, Such as a transform coding System, the input audio
`system, such as a transform coding system, the input audio
`Signal in the time domain is converted into spectral coeffi
`signal in the time domain is converted into spectral coeffi-
`cients in the frequency domain by an orthogonal transform.
`cients in the frequency domain by an orthogonal transform.
`The resulting Spectral coefficients are divided by frequency
`The resulting spectral coefficients are divided by frequency
`into plural frequency bands, and the Spectral coefficients in
`into plural frequency bands, and the spectral coefficients in
`each band are quantized.
`each band are quantized.
`A technique consisting of a combination of Sub-band
`A technique consisting of a combination of sub-band
`coding and transform coding is also known. In this, fre
`coding and transform coding is also known. In this, fre-
`quency range Signals produced by dividing the input audio
`quency range signals produced by dividing the input audio
`Signal in frequency without dividing it into blocks are
`signal in frequency without dividing it into blocks are
`individually orthogonally transformed into Spectral coeffi
`individually orthogonally transformed into spectral coeffi-
`cients. The spectral coefficients are then divided by fre
`cients. The spectral coefficients are then divided by fre-
`quency into plural frequency bands, and the Spectral coef
`quency into plural frequency bands, and the spectral coef-
`ficients in each band are then quantized.
`ficients in each band are then quantized.
`Among the filters useful for dividing a digital audio input
`Among the filters useful for dividing a digital audio input
`Signal into frequency ranges without dividing it into blockS
`signal into frequency ranges without dividing it into blocks
`is the quadrature mirror (QMF) filter, which is described, for
`is the quadrature mirror (QMF) filter, which is described, for
`example, in R. E. Crochiere, Digital Coding of Speech in
`example, in R. E. Crochiere, Digital Coding of Speech in
`Sub-bands, 55 BELL SYST TECH. J. No.8, (1976). A
`Sub-bands, 55 BELL SYST. TECH. J. No.8, (1976). A
`technique of dividing the audio input Signal in frequency
`technique of dividing the audio input signal in frequency
`into frequency bands of an equal width is discussed in
`into frequency bands of an equal width is discussed in
`Joseph H. Rothweiler, Polyphase Quadrature Filers-a New
`Joseph H. Rothweiler, Polyphase Quadrature Filers-a New
`Sub-band Coding Technique, ICASSP83, BOSTON (1983).
`Sub-band Coding Technique, ICASSP 83, BOSTON (1983).
`Known techniques for Orthogonally transforming an input
`Known techniques for orthogonally transforming an input
`Signal include the technique of dividing the digital input
`signal include the technique of dividing the digital input
`audio Signal in time into blocks having a predetermined
`audio signal in time into blocks having a predetermined
`duration, and processing the resulting blocks using a fast
`duration, and processing the resulting blocks using a fast
`Fourier transform (FFT), a discrete cosine transform (DCT),
`Fourier transform (FFT), a discrete cosine transform (DCT),
`or a modified DCT (MDCT) to convert each block of the
`or a modified DCT (MDCT) to convert each block of the
`digital audio signal in the time domain into a set of Spectral
`digital audio signal in the time domain into a set of spectral
`coefficients in the frequency domain. A modified DCT is
`coefficients in the frequency domain. A modified DCT is
`discussed in J. P. Princen and A. B. Bradley, Subband/
`discussed in J. P. Princen and A. B. Bradley, Subbandl
`Transform Coding Using Filter Bank Based on Time
`Transform Coding Using Filter Bank Based on Time
`Domain Aliasing Cancellation, ICASSP 1987.
`Domain Aliasing Cancellation, ICASSP 1987.
`As a technique for quantizing the Spectral coefficients
`As a technique for quantizing the spectral coefficients
`obtained by frequency division, it is known to divide the
`obtained by frequency division, it is known to divide the
`Spectral coefficients by frequency into bands to take account
`spectral coefficients by frequency into bands to take account
`of the frequency resolution characteristics of the human
`of the frequency resolution characteristics of the human
`Sense of hearing. The audio frequency range of 0 Hz to 20
`sense of hearing. The audio frequency range of 0 Hz to 20
`or 22 kHz may be divided in frequency into bands, Such as
`or 22 kHz may be divided in frequency into bands, such as
`25 critical bands, which have a bandwidth that increases
`25 critical bands, which have a bandwidth that increases
`with increasing frequency. The Spectral coefficients in each
`with increasing frequency. The spectral coefficients in each
`of the bands are quantized by adaptive bit allocation applied
`of the bands are quantized by adaptive bit allocation applied
`
`30
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`25
`25
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`2
`2
`to each band. For example, the Spectral coefficients resulting
`to each band. For example, the spectral coefficients resulting
`from a modified discrete cosine transform (MDCT) are
`from a modified discrete cosine transform (MDCT) are
`divided by frequency into bands, and the Spectral coeffi
`divided by frequency into bands, and the spectral coeffi-
`cients in each band are quantized using an adaptively
`cients in each band are quantized using an adaptively-
`determined number of bits.
`5 determined number of bits.
`Two known adaptive bit allocation techniques will be now
`Two known adaptive bit allocation techniques will be now
`be described. First, in the technique described in ASSP-25,
`be described. First, in the technique described in ASSP-25,
`IEEE TRANSACTIONS OF ACOUSTICS, SPEECH, AND
`IEEE TRANSACTIONS OF ACOUSTICS, SPEECH, AND
`SIGNAL PROCESSING, No.4, August 1977, bit allocation
`SIGNAL PROCESSING, No.4, August 1977, bit allocation
`is carried out on the basis of the magnitude of the Signals of
`10 is carried out on the basis of the magnitude of the signals of
`the respective bands. Although this System provides a flat
`the respective bands. Although this system provides a flat
`quantizing noise Spectrum, and minimizes noise energy,
`quantizing noise spectrum, and minimizes noise energy,
`noise perceived by the listener is not minimized because this
`noise perceived by the listener is not minimized because this
`technique does not exploit the masking characteristics of the
`technique does not exploit the masking characteristics of the
`human Sense of hearing.
`15
`15 human sense of hearing.
`On the other hand, the technique described in M. A.
`On the other hand, the technique described in M. A.
`Kransner, The Critical Band Coder-Digital Encoding of the
`Kransner, The Critical Band Coder-Digital Encoding of the
`Perceptual Requirements of the Auditory System, ICASSP
`Perceptual Requirements of the Auditory System, ICASSP
`1980, uses the masking characteristics of the human Sense of
`1980, uses the masking characteristics of the human sense of
`hearing to determine the Signal-to-noise ratio necessary for
`20 hearing to determine the signal-to-noise ratio necessary for
`each band to make a fixed quantizing bit allocation.
`each band to make a fixed quantizing bit allocation.
`However, this technique provides relatively poor results
`However, this technique provides relatively poor results
`with a Single Sine-wave input because of its fixed bit
`with a single sine-wave input because of its fixed bit
`allocation.
`allocation.
`As a high-efficiency System for compressing digital audio
`As a high-efficiency system for compressing digital audio
`Signals, employing, for example, the above-mentioned Sub
`signals, employing, for example, the above-mentioned sub-
`band coding System, a high-efficiency compression System
`band coding system, a high-efficiency compression system
`called ATRAC is already used in practical applications. This
`called ATRAC is already used in practical applications. This
`System compresses digital audio Signals to about 20% of
`system compresses digital audio signals to about 20% of
`their original bit requirement by taking advantage of the
`their original bit requirement by taking advantage of the
`characteristics of the human Sense of hearing using adaptive
`characteristics of the human sense of hearing using adaptive
`transform acoustic coding. ATRAC is a registered trademark
`transform acoustic coding. ATRAC is a registered trademark
`of one of the present assignees (Sony Corporation).
`of one of the present assignees (Sony Corporation).
`Multi-channel audio or Speech Signals in four to eight
`35 Multi-channel audio or speech signals in four to eight
`35
`channels are not only encountered in, for example, com
`channels are not only encountered in, for example, com-
`monplace audio equipment, but are also encountered in
`monplace audio equipment, but are also encountered in
`Stereo or multi-channel Sound Systems, Such as those found
`stereo or multi-channel sound systems, such as those found
`in motion picture theaters, high-quality television Systems,
`in motion picture theaters, high-quality television systems,
`Video tape recorders, and Video disc players. In Such cases,
`40 video tape recorders, and video disc players. In such cases,
`40
`the use of high-efficiency compression is desirable to reduce
`the use of high-efficiency compression is desirable to reduce
`the bit rate required to represent the large number of audio
`the bit rate required to represent the large number of audio
`Signals.
`signals.
`In particular, in commercial applications, a tendency
`In particular, in commercial applications, a tendency
`towards multi-channel digital Sound Signals and equipment
`45 towards multi-channel digital sound signals and equipment
`45
`handling eight-channel digital Sound Signals has developed.
`handling eight-channel digital sound signals has developed.
`Typical of the equipment handling eight-channel digital
`Typical of the equipment handling eight-channel digital
`Sound Signals are motion picture theater Sound Systems, and
`sound signals are motion picture theater sound systems, and
`the apparatus that electronically reproduces the pictures and
`the apparatus that electronically reproduces the pictures and
`Sound of a motion picture film via various electronic media,
`so sound of a motion picture film via various electronic media,
`50
`in particular apparatus Such as high-quality television
`in particular apparatus such as high-quality television
`Systems, Video tape recorders, and Video disc players. In the
`systems, video tape recorders, and video disc players. In the
`Sound Systems of Such apparatus, the tendency is towards
`sound systems of such apparatus, the tendency is towards
`multi-channel Sound Systems of between four and eight
`multi-channel sound systems of between four and eight
`channels.
`55 channels.
`55
`Motion picture theater Sound Systems have recently been
`Motion picture theater sound systems have recently been
`proposed that record on a motion picture film the digital
`proposed that record on a motion picture film the digital
`Sound Signals for the following eight channels: left, left
`sound signals for the following eight channels: left, left-
`center, center, right-center, right, left Surround, right
`center, center, right-center, right, left surround, right
`Surround, and Sub-woofer. These Sound channels are respec
`60 surround, and sub-woofer. These sound channels are respec-
`60
`tively reproduced by left loudspeaker, a left-center
`tively reproduced by left loudspeaker, a left-center
`loudspeaker, a center loudspeaker, a right-center
`loudspeaker, a center loudspeaker, a right-center
`loudspeaker, and a right loudspeaker, all arranged behind the
`loudspeaker, and a right loudspeaker, all arranged behind the
`Screen; a Sub-woofer located behind or in front of the Screen;
`screen; a sub-woofer located behind or in front of the screen;
`and a left-Surround loudspeaker and a right-Surround loud
`65 and a left-surround loudspeaker and a right-surround loud-
`65
`Speaker. For the left-Surround Speaker and the right-Surround
`speaker. For the left-surround speaker and the right-surround
`Speaker, two groups of loudspeakers are respectively
`speaker, two groups of loudspeakers are respectively
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`a much larger number of bits to represent it adequately. Yet
`a much larger number of bits to represent it adequately. Yet
`the present ATRAC system allocates the same number of
`the present ATRAC system allocates the same number of
`bits to each channel, irrespective of the number of bits
`bits to each channel, irrespective of the number of bits
`actually required to adequately represent the Signal in the
`actually required to adequately represent the signal in the
`channel. Thus, to provide its high quality of reproduction,
`5 channel. Thus, to provide its high quality of reproduction,
`there must be Some redundancy in the bit allocation per
`there must be some redundancy in the bit allocation per-
`formed by the present System.
`formed by the present system.
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`3
`3
`arranged on the left side wall and the left part of the back
`arranged on the left side wall and the left part of the back
`wall of the auditorium, and on the right Side wall and the
`wall of the auditorium, and on the right side wall and the
`right part of the back wall of the auditorium. The two groups
`right part of the back wall of the auditorium. The two groups
`of loudspeakers on the Sides and back of the auditorium
`of loudspeakers on the sides and back of the auditorium
`generate a Sound field rich in ambience to accompany
`generate a sound field rich in ambience to accompany
`Spectacular optical effects on the large-format Screen of the
`spectacular optical effects on the large-format screen of the
`motion picture theater. For simplicity, these two groups of
`motion picture theater. For simplicity, these two groups of
`loudspeakers will from now on be referred to as the “left
`loudspeakers will from now on be referred to as the "left-
`SUMMARY OF THE INVENTION
`Surround loudspeaker' and the "right-Surround loud
`SUMMARY OF THE INVENTION
`surround loudspeaker" and the "right-surround loud-
`Speaker.”
`speaker."
`If a multi-channel Sound Signal is to be recorded on a
`If a multi-channel sound signal is to be recorded on a
`It is difficult to record on a motion picture film eight
`motion picture film or on an optical disc, it is necessary to
`It is difficult to record on a motion picture film eight
`motion picture film or on an optical disc, it is necessary to
`channels of 16-bit linear-quantized digital audio with the
`channels of 16-bit linear-quantized digital audio with the
`increase the compression ratio with a minimum deterioration
`increase the compression ratio with a minimum deterioration
`Sampling frequency of 44.1 kHz, Such as is employed in a
`in the Sound quality.
`sampling frequency of 44.1 kHz, such as is employed in a
`in the sound quality.
`compact disc (CD), because the film lacks an area capable
`compact disc (CD), because the film lacks an area capable
`It is therefore an object of the present invention to provide
`It is therefore an object of the present invention to provide
`of accommodating a Soundtrack wide enough for Such a
`of accommodating a soundtrack wide enough for such a
`an encoding method and apparatus for further improving the
`an encoding method and apparatus for further improving the
`signal. The width of the motion picture film and the width of
`signal. The width of the motion picture film and the width of
`compression ratio to enable multi-channel Sound Signals to
`compression ratio to enable multi-channel sound signals to
`the picture area on the film are standardized. The width of
`the picture area on the film are standardized. The width of
`be recorded on a motion picture film, an optical disc, and
`be recorded on a motion picture film, an optical disc, and
`the film cannot be increased, or the width of the picture area
`the film cannot be increased, or the width of the picture area
`other media, or to be transmitted or distributed.
`other media, or to be transmitted or distributed.
`cannot be decreased to accommodate a Soundtrack of the
`cannot be decreased to accommodate a soundtrack of the
`It is another object of the present invention to provide an
`It is another object of the present invention to provide an
`width required for digital audio Signals of this type. A
`20
`width required for digital audio signals of this type. A
`encoding method and apparatus for encoding Sound Signals
`encoding method and apparatus for encoding sound signals
`Standard-width film, with a Standard picture area, a Standard
`standard-width film, with a standard picture area, a standard
`of at least two channels with an extremely Small degree of
`of at least two channels with an extremely small degree of
`analog Sound track, and Standard perforations, has only a
`analog sound tra