Digital audio signal decoding apparatus, decoding method and a recording medium storing the decoding steps

Claim 2

A decoding apparatus according to claim 1 for decoding a bit stream by performing a band synthesis up to a maximum of N channels (N is an integer larger than 1), wherein said decoding section comprises: a band signal generator (4a) for generating a band signal by applying inverse quantization to said encoded data, a band synthesizer (4d) for generating PCM data for each output channel by applying said band synthesis to said band signal, and an interleaver (4e) for performing an interleaving process whereby said band-synthesized and decoded PCM data for each output channel is reordered sample by sample in a prescribed sequence, thereby generating audio output data.

Claim 3

A decoding apparatus for decoding a bit stream constructed in accordance with an MPEG-1 audio specification and an MPEG-2 audio specification and decodable by a band synthesis up to a maximum of N channels (N is an integer larger than 1), comprising: a stream input section (1) for separating an input bit stream into auxiliary information and audio encoded data, an auxiliary information analyzing section (2) for analyzing said auxiliary information supplied from said stream input section, and for obtaining at least Fs information indicative of a sampling frequency, full channel configuration information, and dematrix procedure information, a parameter ROM section prestoring (5,15,48) therein a decoding control table (8) which presents decoding type numbers classified according to said full channel configuration information and said dematrix procedure information, a decoding control section (3) for selecting a decoding type number from said decoding control table on the basis of said full channel configuration information and said dematrix procedure information supplied from said auxiliary information analyzing section, and for performing decoding control based on said selected type number, a decoding section (4) comprising a band signal generator (4a) for generating a band signal by applying an inverse quantization to said audio encoded data, a dematrix processor (4b,14b,24b) for applying a dematrixing process to said band signal and thereby converting said band signal into a band signal for each output channel, a band synthesizer (4d) for generating PCM data for each output channel by applying said band synthesis to said band signal supplied from said dematrix processor, and an interleaver (4e) for performing an interleaving process whereby said band-synthesized and decoded PCM data for each output channel is reordered sample by sample in a prescribed sequence, thereby generating audio output data, wherein said decoding section generates said audio data in accordance with an instruction from said decoding control section, and a storage section (6) for storing at least said PCM data output from said band synthesizer.

Claim 4

A decoding apparatus according to claim 3, wherein said auxiliary information analyzing section comprises: an MPEG-1 header analyzer (2a) for analyzing header information defined in accordance with said MPEG-1 audio specification, thereby extracting at least said Fs information and determining whether front output channel configuration is monaural (one channel) or stereo (two channels), an MC header analyzer (2b) for analyzing header information defined in accordance with said MPEG-2 audio specification, thereby extracting at least said dematrix information and determining the presence or absence of a front center channel and also a rear channel configuration or the presence of absence of second stereo channels, and for generating said full channel configuration information by combining the result of said analysis with the information of said front channel configuration obtained by said MPEG-1 header analyzer, and a header information compatibility corrector (2c) for generating said full channel configuration information and said dematrix procedure information by determining the number of front channels from said MPEG-1 audio specification defined header information, and assuming that the front center channel and the rear channels or second stereo channels do not exist, when decoding the bit stream constructed in accordance with said MPEG-1 audio specification.

Claim 5

A decoding apparatus according to claim 3 or 4, wherein said decoding control table comprises: a decoding type instruction table (8a) which presents decoding type numbers classified according to said full channel configuration information and said dematrix procedure information, and a decoding control information instruction table (8b) which presents decoding control information consisting of a combination of multiple pieces of decoding instruction information for each of said decoding type numbers.

Claim 6

A decoding apparatus according to any one of claims 3 to 5, wherein said dematrix processor includes a dematrix band limiter (13) for limiting the number of bands to be dematrixed in said band signal on the basis of said Fs information supplied from said auxiliary information analyzing section.

Claim 7

A decoding apparatus according to any one of claims 3 to 6, wherein said decoding control table contains channel number information to indicate the number of output channels to be generated by said band synthesis based on said full channel configuration information, and said decoding control section includes a channel number transmitting unit (3c) for transmitting said channel number information, obtained from said decoding control table, to said decoding section.

Claim 8

A decoding apparatus according to any one of claims 3 to 7, wherein said decoding control section includes a dematrix instruction unit (3a) which gives an instruction for said dematrixing process, based on said full channel configuration information and said dematrix procedure information supplied from said auxiliary information analyzing section and by using a value retrieved from said decoding control table in said parameter ROM.

Claim 9

A decoding apparatus according to claim 8, wherein said decoding control table contains dematrix pattern information indicating a dematrixing pattern, said dematrix processor comprises individual dematrixing blocks (12a,--,12g) each provided in corresponding relationship to said dematrix pattern information, and said parameter ROM prestores therein a dematrix pattern address table (9) which defines correspondence between said dematrix pattern information and said dematrixing blocks contained in said dematrix processor.

Claim 10

A decoding apparatus according to claim 8, wherein said dematrix processor (14b) comprises a general purpose dematrixing block (17) which performs said dematrixing process by varying a dematrix coefficient according to said full channel configuration information and said dematrix procedure information, said decoding control table contains dematrix pattern information indicating a dematrixing pattern, and said parameter ROM prestores therein a pattern-by-pattern dematrix coefficient table (16) which defines correspondence between said dematrix coefficient and said dematrix pattern information.

Claim 11

A decoding apparatus according to claim 8, wherein said dematrix processor (24b) comprises a general purpose dematrixing block (27) which performs said dematrixing process by varying a dematrix coefficient according to said full channel configuration information and said dematrix procedure information, and at least one dematrixing block (12f,12g) corresponding to a predesignated channel, said decoding control table contains dematrix pattern information indicating a dematrixing pattern, and said parameter ROM (18) prestores therein a dematrix pattern address table (19) which defines correspondence among said dematrix pattern information, said general purpose dematrixing block and said at least one dematrixing block, and a pattern-by-pattern dematrix coefficient table (20) which defines correspondence between said dematrix coefficient and said dematrix pattern information.

Claim 12

A decoding apparatus according to claim 11, wherein said dematrix processor comprises a general purpose dematrixing block which varies said dematrix coefficient in cases where the number of output channels to be generated by said band synthesis is 1 to M (M is an integer smaller than N), and a dematrixing block provided for cases where the number of output channels to be generated by said band synthesis is equal to or larger than (M+1), and said parameter ROM prestores therein a pattern-by-pattern dematrix coefficient table which defines correspondence between said general purpose dematrixing block and said dematrix pattern information corresponding to 1 to M output channels.

Claim 13

A decoding apparatus according to any one of claims 3 to 12, wherein said decoding control table contains an interleave instruction information for indicating an interleaving pattern based on said full channel configuration information, and said decoding control section includes an interleave instruction unit (3d) for indicating said interleave instruction information, obtained from said decoding control table, to said decoding section.

Claim 14

A decoding apparatus according to claim 13, wherein said interleave instruction information is information that indicates said interleaving pattern, preassigned according to said full channel configuration information, by using a number, said parameter ROM prestores therein an interleave pattern table (11) which defines correspondence between said number of said interleaving pattern and PCM location information which is an encoded representation of the starting address of said PCM data stored in said storage section.

Claim 15

A decoding apparatus according to any one of claims 3 to 14, wherein said decoding section includes a mute data creator (4h) which writes mute PCM data to said storage section when said channel number information supplied from said decoding control section indicates (N-1) or fewer channels.

Claim 16

A decoding apparatus according to any one of claims 3 to 15, wherein said parameter ROM prestores therein a denormalization instruction table (10 )for indicating instruction data for a denormalization process according to said full channel configuration information and said dematrix procedure information supplied from said auxiliary information analyzing section, said decoding control section includes a denormalization instruction unit (3b) which gives an instruction for said denormalization process, based on said full channel configuration information and said dematrix procedure information supplied from said auxiliary information analyzing section and by using a value retrieved from said denormalization instruction table in said parameter ROM, and said decoding unit includes a denormalization processor (4c) which performs said denormalization process in accordance with said instruction from said decoding control section.

Claim 17

A decoding apparatus according to claim 16, wherein said denormalization instruction table comprises: a normalization type instruction table (10a) which presents denormalization type numbers classified according to said full channel configuration information and said dematrix procedure information, a denormalization allocation table (10b) which shows relations between said denormalization type numbers and denormalize correction value data numbers for each output channel, and a denormalization level correction value table (10c) for converting said denormalize correction value data numbers into sound level data used in said denormalization.

Claim 18

A decoding apparatus according to claim 16 or 17, further comprising a channel balance setting interface (7) via which sound level information for each output channel is supplied from outside for delivery to said decoding section, and wherein: said decoding section includes a sound level converter (4f) which converts said sound level information delivered from said channel balance setting interface into sound level data for each output channel, and a classifying sound level multiplier (4g) which multiplies said instruction data supplied from said denormalization instruction unit by said sound level data supplied from said sound level converter for each output channel when said channel number information from said decoding control section indicates N, and said interleave processor includes a classifying interleave sound level adjuster multiplies said PCM data of each output channel by said sound level data supplied from said sound level converter when said channel number information from said decoding control section indicates (N-1) or fewer channels.

Claim 19

A decoding method for use in a decoding apparatus for decoding a bit stream for a maximum of N channels (N is an integer larger than 1), comprising: a separation step for separating an input bit stream into auxiliary information and encoded data, an auxiliary information analyzing step for obtaining at least full channel configuration information by analyzing said auxiliary information separated in said separation step, a selection step for selecting a decoding type number from a decoding control table in a parameter ROM on the basis of said full channel configuration information obtained in said auxiliary information analyzing step, and a generation step for generating output data by performing decoding control based on said type number selected in said selection step.

Claim 20

A decoding method according to claim 19 for use in a decoding apparatus for decoding a bit stream by performing band synthesis up to a maximum of N channels (N is an integer larger than 1), wherein said generation step comprises: a band signal generation step for generating a band signal by applying an inverse quantization to said encoded data, a band synthesizing step for generating PCM data for each output channel by applying a band synthesis to said band signal generated in said band signal generation step, and an interleaving step for performing an interleaving process whereby said PCM data generated for each output channel in said band synthesizing step is reordered sample by sample in a prescribed sequence.

Claim 21

A decoding method for use in a decoding apparatus for decoding a bit stream constructed in accordance with an MPEG-1 audio specification and an MPEG-2 audio specification and decodable by a band synthesis up to a maximum of N channels (N is an integer larger than 1), comprising: a separation step for separating an input bit stream into auxiliary information and audio encoded data, an auxiliary information analyzing step for analyzing said auxiliary information separated in said separation step, and for obtaining at least Fs information indicative of a sampling frequency, full channel configuration information, and dematrix procedure information, a selection step for selecting a decoding type number from a decoding control table in a parameter ROM on the basis of said full channel configuration information and said dematrix procedure information obtained in said auxiliary information analyzing step, and a generation step for generating audio output data by performing decoding control based on said type number selected in said selection step.

Claim 22

A decoding method for used in a decoding apparatus according to claim 21, wherein said generation step comprises: a band signal generation step for generating a band signal by applying an inverse quantization to said audio encoded data, a dematrixing step for applying a dematrixing process to said band signal generated in said band signal generation step, and thereby converting said band signal into a band signal for each output channel, a band synthesizing step for generating PCM data for each output channel by applying said band synthesis to said band signal generated for each output channel in said dematrixing step, and an interleaving step for performing an interleaving process whereby said PCM data generated for each output channel in said band synthesizing step is reordered sample by sample in a prescribed sequence.

Claim 23

A recording medium having decoding steps recorded thereon for decoding a bit stream for a maximum of N channels (N is an integer larger than 1), said decoding steps comprising the steps of: when said bit stream is input, separating said bit stream into auxiliary information and encoded data, acquiring at least full channel configuration information by analyzing said separated auxiliary information, selecting a decoding type number from a decoding control table in a parameter ROM on the basis of said acquired full channel configuration information, and generating output data by performing decoding control based on said selected type number.

Claim 24

A recording medium having decoding steps recorded thereon according to claim 23 for decoding a bit stream by a band synthesis up to a maximum of N channels (N is an integer larger than 1), wherein said decoding steps provide an additional function by which, when generating said output data, a band signal is generated by applying an inverse quantization to said encoded data, PCM data for each output channel is generated by applying a band synthesis to said band signal, and an interleaving process is performed whereby said PCM data for each output channel is reordered sample by sample in a prescribed sequence.

Claim 25

A recording medium having decoding steps recorded thereon for decoding a bit stream constructed in accordance with an MPEG-1 audio specification and an MPEG-2 audio specification and decodable by a band synthesis up to a maximum of N channels (N is an integer larger than 1), said decoding steps comprising the steps of: when said bit stream is input, separating said bit stream into auxiliary information and audio encoded data, acquiring at least Fs information indicative of a sampling frequency, full channel configuration information, and dematrix procedure information by analyzing said separated auxiliary information, selecting a decoding type number from a decoding control table in a parameter ROM on the basis of said acquired full channel configuration information and dematrix procedure information, and generating audio output data by performing decoding control based on said selected type number.

Claim 26

A recording medium having decoding steps recorded thereon according to claim 25, wherein said decoding steps provide an additional function by which, when generating said audio output data, a band signal is generated by applying an inverse quantization to said audio encoded data, said band signal is dematrixed and thereby converted into a band signal for each output channel, PCM data for each output channel is generated by applying said band synthesis to said band signal of each output channel, and an interleaving process is performed whereby said PCM data for each output channel is reordered sample by sample in a prescribed sequence.