ENCODING METHOD, DECODING METHOD, DEVICE, PROGRAM, AND RECORDING MEDIUM

• US 20130114733A1
• Filed: 07/04/2011
• Published: 05/09/2013
• Est. Priority Date: 07/05/2010
• Status: Abandoned Application

• Current Assignee: Nippon Telegraph and Telephone Corporation
• Original Assignee: Nippon Telegraph and Telephone Corporation
• Inventors: Fukui, Masahiro, Sasaki, Shigeaki, Hiwasaki, Yusuke, Koyama, Shoichi, Tsutsumi, Kimitaka
• Application Number:
  US13/807,098
• Publication Number:
  US 20130114733A1
• Time in Patent Office: Days
• US Class Current: 375/240.22
• CPC Class Codes: G10L 19/038 Vector quantisation, e.g. TwinVQ audio
• CPC Class Codes: H03M 7/3082 Vector coding for television signals, see H04N19/94
• CPC Class Codes: H04N 19/126 Details of normalisation or weighting functions, e.g. normalisation matrices or variable uniform quantisers
• CPC Class Codes: H04N 19/94 Vector quantisation

Abstract

When a number of samples which are less than a first reference value is a second reference value or less, a second encoding mode is selected. In the second encoding mode, when a difference value that is obtained by subtracting a value corresponding to the quantized normalization value from a value corresponding to the magnitude of each sample is positive and the sample is positive, the difference value is set as a quantization candidate corresponding to the sample; when the difference value is positive and the sample is negative, the sign of the difference value is reversed and the result is set as the quantization candidate corresponding to the sample; and a plurality of quantization candidates are jointly vector-quantized to obtain a vector quantization index. When the second encoding mode is not selected, a first encoding mode other than the second encoding mode is selected.

Claims

1. An encoding method comprising:

an encoding mode selecting step of selecting a second encoding mode when an evaluation value is a second reference value or less, selecting a first encoding mode other than the second encoding mode when the second encoding mode is not selected, and generating mode information representing a selected encoding mode, wherein the evaluation value corresponds to the number of samples which correspond to values less than a first reference value among a predetermined number of input samples, and the second encoding mode is a mode in which a normalization value that is a representative value of the predetermined number of samples is quantized to obtain a quantized normalization value and a normalization-value quantization index corresponding to the quantized normalization value, a difference value that is obtained by subtracting a value corresponding to the quantized normalization value from a value corresponding to the magnitude of each sample is set as a quantization candidate corresponding to the sample when the difference value is positive and the sample is positive, the sign of the difference value is reversed and the result is set to the quantization candidate corresponding to the sample when the difference value is positive and the sample is negative, and a plurality of quantization candidates are jointly vector-quantized to obtain a vector quantization index; and

an encoding step of encoding the predetermined number of samples by the first encoding mode or the second encoding mode that is selected in the encoding mode selecting step.

2. The encoding method according to claim 1, wherein at least some of the evaluation value is a weighted addition value of an evaluation value calculated in previous time and the number of samples which correspond to values less than the first reference value.

3. The encoding method according to claim 1 or 2, wherein the second reference value when a previous predetermined number of samples are encoded by the first encoding mode is smaller than when the previous predetermined number of samples are encoded by the second encoding mode.

4. The encoding method according to claim 3, wherein the evaluation value is a value corresponding to the number of samples which include samples satisfying a criterion based on auditory perceptual characteristics and which correspond to values less than the first reference value among the predetermined number of samples.

5. The encoding method according to claim 1 or 2, wherein the evaluation value is a value corresponding to the number of samples which include samples satisfying a criterion based on auditory perceptual characteristics and which correspond to values less than the first reference value among the predetermined number of samples.

6. The encoding method according to claim 1, wherein the first encoding mode is a mode in which the vector quantization index is obtained by vector-quantizing according to a vector quantization mode in which non-zero quantized values are obtained only for some of the predetermined number of samples and zero quantized values are obtained for the remaining samples.

7. The encoding method according to claim 1, wherein the first encoding mode is a mode in which a normalization value that is representative of the predetermined number of samples is quantized to obtain a quantized normalization value and a normalization-value quantization index corresponding to the quantized normalization value, and a predetermined number of normalized samples that are obtained by normalizing the predetermined number of samples are vector-quantized by a vector quantization mode in which non-zero quantized values are obtained only for some of the predetermined number of normalized samples and zero quantized values are obtained for the remaining normalized samples to obtain the vector quantization index.

8. The encoding method according to claim 1, wherein the second encoding mode includes a process of setting zero as the quantization candidate corresponding to each of the samples when the difference value is not positive.

21. A non-transitory computer-readable recording medium on which a program for causing a computer to perform each step of the encoding method according to claim 1 is stored.

9. A decoding method comprising:

a switching step of selecting a second decoding mode when input mode information has a second value, and selecting a first decoding mode other than the second decoding mode when the mode information has a first value, wherein the second decoding mode is a mode in which a decoded normalization value corresponding to an input normalization-value quantization index is obtained, a plurality of values corresponding to an input vector quantization index are obtained as decoded values, a value having a magnitude corresponding to a recalculated normalization value that takes on a value that decreases with increasing sum of the absolute values of a predetermined number of the decoded values is obtained as a decoded signal when the decoded value is zero, a linear sum of the decoded value and the decoded normalization value is obtained as a decoded signal when the decoded value is positive, and a sign of the linear sum of the absolute value of the decoded value and the decoded normalization value is reversed and the result is set as a decoded signal when the decoded value is negative; and

a decoding step of performing a decoding process in the first decoding mode or the second decoding mode that is selected in the switching step.

22. A non-transitory computer-readable recording medium on which a program for causing a computer to perform each step of the decoding method according to claim 9 is stored.

10. An encoding device comprising:

an encoding mode selector that selects a second encoding mode when an evaluation value is a second reference value or less, selects a first encoding mode other than the second encoding mode when the second encoding mode is not selected, and generates mode information representing a selected encoding mode, wherein the evaluation value corresponds to the number of samples which correspond to values less than a first reference value among a predetermined number of input samples, and the second encoding mode is a mode in which a normalization value that is a representative value of the predetermined number of samples is quantized to obtain a quantized normalization value and a normalization-value quantization index corresponding to the quantized normalization value, a difference value that is obtained by subtracting a value corresponding to the quantized normalization value from a value corresponding to the magnitude of each sample is set as a quantization candidate corresponding to the sample when the difference value is positive and the sample is positive, the sign of the difference value is reversed and the result is set to the quantization candidate corresponding to the sample when the difference value is positive and the sample is negative, and a plurality of quantization candidates are jointly vector-quantized to obtain a vector quantization index; and

an encoder that encodes the predetermined number of samples by the first encoding mode or the second encoding mode that is selected by the encoding mode selector.

11. The encoding device according to claim 10, wherein at least some of the evaluation value is a weighted addition value of an evaluation value calculated in previous time and the number of samples which correspond to values less than the first reference value.

12. The encoding device according to claim 10 or 11, wherein the second reference value when a previous predetermined number of samples are encoded by the first encoding mode is smaller than when the previous predetermined number of samples are encoded by the second encoding mode.

13. The encoding device according to claim 12, wherein the evaluation value is a value corresponding to the number of samples which include samples satisfying a criterion based on auditory perceptual characteristics and which correspond to values less than the first reference value among the predetermined number of samples.

14. The encoding device according to claim 10 or 11, wherein the evaluation value is a value corresponding to the number of samples which include samples satisfying a criterion based on auditory perceptual characteristics and which correspond to values less than the first reference value among the predetermined number of samples.

15. The encoding device according to claim 10, wherein the first encoding mode is a mode in which the vector quantization index is obtained by vector-quantizing according to a vector quantization mode in which non-zero quantized values are obtained only for some of the predetermined number of samples and zero quantized values are obtained for the remaining samples.

16. The encoding device according to claim 10, wherein the first encoding mode is a mode in which a normalization value that is representative of the predetermined number of samples is quantized to obtain a quantized normalization value and a normalization-value quantization index corresponding to the quantized normalization value, and a predetermined number of normalized samples that are obtained by normalizing the predetermined number of samples are vector-quantized by a vector quantization mode in which non-zero quantized values are obtained only for some of the predetermined number of normalized samples and zero quantized values are obtained for the remaining normalized samples to obtain the vector quantization index.

17. The encoding device according to claim 10, wherein the second encoding mode includes a process of setting zero as the quantization candidate corresponding to each of the samples when the difference value is not positive.

18. A decoding device comprising:

a switching unit that selects a second decoding mode when input mode information has a second value, and selects a first decoding mode other than the second decoding mode when the mode information has a first value, wherein the second decoding mode is a mode in which a decoded normalization value corresponding to an input normalization-value quantization index is obtained, a plurality of values corresponding to an input vector quantization index are obtained as decoded values, a value having a magnitude corresponding to a recalculated normalization value that takes on a value that decreases with increasing sum of the absolute values of a predetermined number of the decoded values is obtained as a decoded signal when the decoded value is zero, a linear sum of the decoded value and the decoded normalization value is obtained as a decoded signal when the decoded value is positive, and a sign of the linear sum of the absolute value of the decoded value and the decoded normalization value is reversed and the result is set as a decoded signal when the decoded value is negative; and

a decoder of performing a decoding process in the first decoding mode or the second decoding mode that is selected by the switching unit.

19-20. -20. (canceled)