Audio coder
AssigneeFujitsu Limited
InventorsHitoshi Sasaki, Yasuji Ota
Life of this patent
Estimating the term…
Abstract
An audio coder that improves audio quality by reducing a quantization error. When a code corresponding to a sampled value of an audio signal is determined, a candidate code storage section stores all combinations of candidate codes in a neighborhood interval of the sampled value. A local decoder generates reproduced signals by decoding the codes stored in the candidate code storage section. An error evaluation section calculates, for each candidate code, a sum of squares of differentials between input sampled values and reproduced signals, detects a combination of candidate codes by which a smallest sum is obtained, that is to say, which minimizes a quantization error, and outputs a code included in the detected combination of candidate codes.
Claims5
An audio coder for coding an audio signal, the coder comprising:
- a candidate code storage section for storing, at the time of determining a code corresponding to a sampled value of the audio signal, a plurality of combinations of candidate codes in a neighborhood interval of the sampled value;
- a decoded signal generation section for generating reproduced signals by decoding the codes stored in the candidate code storage section;
- and
- an error evaluation section for calculating, for each candidate code, a sum of squares of differentials between input sampled values and reproduced signals, detecting a combination of candidate codes by which a smallest sum is obtained, that is to say, which minimizes a quantization error, and outputting a code included in the detected combination of candidate codes.
A method for coding a signal, the method comprising, at the time of determining a code corresponding to a sampled value at time n and in the case of time (n+k) being set with pr future samples as a neighborhood interval (0≦k≦pr), the steps of:
- storing a plurality of combinations of candidate codes J{j1, j2, . . . , jk, j(k+1)} which correspond to sampled values at time n through (n+k) respectively;
- generating reproduced signals sr(J) in order from the codes j1, j2, . . . , jk, and j(k+1);
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- detecting a combination of candidate codes {j1, j2, . . . , jk, j(k+1)} which minimizes error evaluation value e(J) given by
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- and outputting the code j1 included in the detected combination of candidate codes {j1, j2, . . . , jk, j(k+1)} as the code at time n, where in is an input sampled value and 0≦k≦pr.
Dependencies are inferred from the claim text.