Digital signal coding and decoding methods and apparatuses and programs therefor
AssigneeNippon Telegraph and Telephone Corporation
InventorsTakehiro Moriya, Akio Jin, Takeshi Mori, Kazunaga Ikeda
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Abstract
At the coder side, bits of samples of each frame of an input digital signal are concatenated every digit common to the samples across each frame to generate equi-order bit sequences, which are output as packets. At the decoding side, the input equi-order sequences are arranged inversely to their arrangement at the coder side to reconstruct sample sequences. When a packet dropout occurs, a missing information compensating part 430 correct the reconstructed sample sequences in a manner to reduce an error between the spectral envelope of the reconstructed sample sequence concerned and a known spectral envelope.
Claims17
A coding method for encoding a digital signal for each frame comprising a plurality of samples, comprising the steps of:
- (a) determining, as a number of effective digits, a number of digits representing a maximum value of an absolute value of the amplitude of said digital signal in each frame;
- (b) generating sets of data consisting of either lossless data of at least one bitstream or lossy data and lossless data of an error signal due to said lossy data of at least one bitstream, over said samples at each bit position within said number of effective digits in said each frame;
- and
- (c) outputting said sets of data and said number of effective digits.
A decoding method which reconstructs a sequence of samples of a digital signal for each frame, comprising the steps of:
- (a) decoding input auxiliary information to obtain a number of effective digits for each frame and decoding input codes to produce sets of data consisting of either lossless data of at least one bitstream or lossy data and lossless data of an error signal due to the lossy data of at least one bitstream, over said samples at each bit position within said number of effective digits in said each frame;
- and
- (b) reconstructing a digital signal based on said sets of data and adjusting digits of said samples of said digital signal in said each frame in accordance with the number of the effective digits.
A coder for coding a digital signal for each frame, comprising:
- auxiliary information generating part for obtaining and outputting, as an effective digit number, a number of digits representing a maximum value of an absolute value of the amplitude of said digital signal of each frame;
- means for generating sets of data consisting of either lossless data of at least one bitstream or lossy data and lossless data of an error signal due to said lossy data of at least one bitstream, over said samples at each bit position within said number of effective digits of said digital signal in said each frame;
- and
- output means for outputting said sets of data and said number of effective digits.
A decoder which reconstructs a sequence of samples of a digital signal for each frame, comprising:
- an auxiliary information decoding part for decoding input auxiliary information to obtain a number of effective digits for each frame;
- means for decoding input codes to produce sets of data consisting of either lossless data of at least one bitstream or lossy data and lossless data of an error signal due to said lossy data of at least one bitstream, over said samples at each bit position within said number of effective digits in said each frame;
- means for reconstructing a digital signal based on said sets of data;
- and
- a digit adjusting part for adjusting digits of said samples of said digital signal in said each frame in accordance with the number of the effective digits.
Dependencies are inferred from the claim text.