Encoding method for acquiring codes corresponding to prediction residuals, decoding method for decoding codes corresponding to noise or pulse sequence, encoder, decoder, program, and recording medium

Patent metadata

Field	Value
Publication number	US-9230554-B2
Application number	US-201213984773-A
Country	US
Kind code	B2
Filing date	Feb 8, 2012
Priority date	Feb 16, 2011
Publication date	Jan 5, 2016
Grant date	Jan 5, 2016

Abstract

In encoding, the number of bits to be assigned to codes corresponding to noise or a pulse sequence obtained according to prediction analysis applied to time series signals included in a predetermined time interval is switched according to whether an index that indicates a level of periodicity and/or stationarity of input time series signals satisfies a condition that indicates high periodicity and/or high stationarity or a condition that indicates low periodicity and/or low stationarity, to acquire the codes corresponding to the noise and the pulse sequence. In decoding, a decoding mode for codes corresponding to noise or a pulse sequence included in codes corresponding to a predetermined time interval is switched according to the same criterion as that described above to decode the codes corresponding to the noise or the pulse sequence to acquire noise or a pulse sequence corresponding to the predetermined time interval.

First claim

What is claimed is:

1. A computer-implemented encoding method executing on a processor, the method comprising acquiring codes corresponding to prediction residuals obtained according to prediction analysis applied to time series signals included in a predetermined time interval of input time series signals which are speech or acoustic signals, with the number of bits to be assigned to the codes corresponding to the prediction residuals being switched according to whether an index that indicates a level of periodicity and/or stationarity corresponding to the time series signals in the predetermined time interval or time series signals in an interval before the predetermined time interval of the input time series signals satisfies a condition that indicates high periodicity and/or high stationarity or a condition that indicates low periodicity and/or low stationarity,
wherein the number of bits of the codes corresponding to the prediction residuals, obtained when the index that indicates the level of periodicity and/or stationarity satisfies the condition that indicates high periodicity and/or high stationarity, is smaller than the number of bits of the codes corresponding to the prediction residuals, obtained when the index that indicates the level of periodicity and/or stationarity does not satisfy the condition that indicates high periodicity and/or high stationarity; or
the number of bits of the codes corresponding to the prediction residuals, obtained when the index that indicates the level of periodicity and/or stationarity satisfies the condition that indicates low periodicity and/or low stationarity, is larger than the number of bits of the codes corresponding to the prediction residuals, obtained when the index that indicates the level of periodicity and/or stationarity does not satisfy the condition that indicates low periodicity and/or low stationarity,
wherein a predetermined total number of bits is assigned to codes corresponding to a time interval that includes the predetermined time interval and a second predetermined time interval after the predetermined time interval; and
the number of bits to be assigned to codes corresponding to second prediction residuals obtained according to prediction analysis applied to time series signals included in the second predetermined time interval is determined according to the number of unassigned bits determined from the total number of bits and the number of bits to be assigned to the codes corresponding to the prediction residuals obtained according to the prediction analysis applied to the time series signals included in the predetermined time interval, to acquire, with the determined number of bits, the codes corresponding to the second prediction residuals.

2. The encoding method according to claim 1 ,
wherein the index includes a quantized pitch gain or a value corresponding thereto;
the condition that indicates high periodicity and/or high stationarity includes a condition that indicates that the quantized pitch gain or the value corresponding thereto is larger than a predetermined specified value; or
the condition that indicates low periodicity and/or low stationarity includes a condition that indicates that the quantized pitch gain or the value corresponding thereto is smaller than the predetermined specified value.

3. The encoding method according to claim 1 ,
wherein the index includes a vector-quantized gain code corresponding to a combination of a quantized pitch gain or a value corresponding thereto, and a quantized fixed-codebook gain or a value corresponding thereto;
the condition that indicates high periodicity and/or high stationarity includes a condition that indicates that the vector-quantized gain code corresponds to a combination of a quantized pitch gain or a value corresponding thereto that is larger than a predetermined specified value, and a quantized fixed-codebook gain or a value corresponding thereto; or
the condition that indicates low periodicity and/or low stationarity includes a condition that indicates that the vector-quantized gain code corresponds to a combination of a quantized pitch gain or a value corresponding thereto that is smaller than the predetermined specified value, and a quantized fixed-codebook gain or a value corresponding thereto.

4. The encoding method according to claim 1 ,
wherein the index includes a quantized pitch gain or a value corresponding thereto, and a quantized fixed-codebook gain or a value corresponding thereto;
the condition that indicates high periodicity and/or high stationarity includes a condition that indicates that a ratio of the quantized pitch gain or the value corresponding thereto to the quantized fixed-codebook gain or the value corresponding thereto is larger than a predetermined specified value; or
the condition that indicates low periodicity and/or low stationarity includes a condition that indicates that a ratio of the quantized pitch gain or the value corresponding thereto to the quantized fixed-codebook gain or the value corresponding thereto is smaller than a predetermined specified value.

5. The encoding method according to claim 1 ,
wherein the index includes a vector-quantized gain code corresponding to a combination of a quantized pitch gain or a value corresponding thereto, and a quantized fixed-codebook gain or a value corresponding thereto;
the condition that indicates high periodicity and/or high stationarity includes a condition that indicates that the vector-quantized gain code corresponds to a combination of a quantized pitch gain or a value corresponding thereto, and a quantized fixed-codebook gain or a value corresponding thereto, a ratio of the quantized pitch gain or the value corresponding thereto to the quantized fixed-codebook gain or the value corresponding thereto being larger than a predetermined specified value; or
the condition that indicates low periodicity and/or low stationarity includes a condition that indicates that the vector-quantized gain code corresponds to a combination of a quantized pitch gain or a value corresponding thereto, and a quantized fixed-codebook gain or a value corresponding thereto, a ratio of the quantized pitch gain or the value corresponding thereto to the quantized fixed-codebook gain or the value corresponding thereto being smaller than the predetermined specified value.

6. The encoding method according to claim 1 ,
wherein the index includes a quantized pitch gain or a value corresponding thereto, and a value corresponding to a quantized fixed-codebook gain;
the condition that indicates high periodicity and/or high stationarity includes a condition that indicates that the quantized pitch gain or the value corresponding thereto is larger than a first predetermined specified value and that the value corresponding to the quantized fixed-codebook gain is smaller than a second predetermined specified value; or
the condition that indicates low periodicity and/or low stationarity includes a condition that indicates that the quantized pitch gain or the value corresponding thereto is smaller than a first predetermined specified value and that the value corresponding to the quantized fixed-codebook gain is larger than a second predetermined specified value.

7. The encoding method according to claim 1 ,
wherein the index includes a vector-quantized gain code corresponding to a combination of a quantized pitch gain or a value corresponding thereto, and a value corresponding to a quantized fixed-codebook gain;
the condition that indicates high periodicity and/or high stationarity includes a condition that indicates that the quantized pitch gain or the value corresponding thereto corresponding to the vector-quantized gain code is larger than a first predetermined specified value and that the

Assignees

• Moriya Takehiro
• Harada Noboru
• Kamamoto Yutaka
• Hiwasaki Yusuke
• Fukui Masahiro
• Nippon Telegraph & Telephone

Inventors

• Moriya Takehiro
• Harada Noboru
• Kamamoto Yutaka
• Hiwasaki Yusuke
• Fukui Masahiro

Classifications

• H03M5/06

  Code representation, e.g. transition, for a given bit cell depending only on the information in that bit cell · CPC title

• G10L19/18

  Vocoders using multiple modes · CPC title

• G10L19/12 Primary

  the excitation function being a code excitation, e.g. in code excited linear prediction [CELP] vocoders · CPC title

• G10L19/09 Primary

  Long term prediction, i.e. removing periodical redundancies, e.g. by using adaptive codebook or pitch predictor · CPC title