Encoder, decoder, encoding method, and decoding method

• US 7,769,584 B2
• Filed: 11/02/2005
• Issued: 08/03/2010
• Est. Priority Date: 11/05/2004
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Oshikiri, Masahiro, Yoshida, Koji, Ehara, Hiroyuki
• Primary Examiner(s): AZAD, ABUL K
• Application Number:
  US11/718,452
• Publication Number:
  US 20080052066A1
• Time in Patent Office: 1,735 Days
• Field of Search: 704/205, 704/206, 704220-223, 704/230, 704500-504
• US Class Current: 704/230
• CPC Class Codes: G10L 21/038 using band spreading techniques

Abstract

An encoder, decoder, encoding method, and decoding method enabling acquisition of high-quality decoded signal in scalable encoding of an original signal in first and second layers even if the second or upper layer section performs low bit-rate encoding. In the encoder, a spectrum residue shape codebook (305) stores candidates of spectrum residue shape vectors, a spectrum residue gain codebook (307) stores candidates of spectrum residue gains, and a spectrum residue shape vector and a spectrum residue gain are sequentially outputted from the candidates according to the instruction from a search section (306). A multiplier (308) multiplies a candidate of the spectrum residue shape vector by a candidate of the spectrum residue gain and outputs the result to a filtering section (303). The filtering section (303) performs filtering by using a pitch filter internal state set by a filter state setting section (302), a lag T outputted by a lag setting section (304), and a spectrum residue shape vector which has undergone gain adjustment.

Claims

1. An encoding apparatus that generates low-frequency-band encoding information and high-frequency-band encoding information from an original signal, the encoding apparatus comprising:

a first spectrum calculating section that calculates a first spectrum of a low frequency band from a decoded signal of the low-frequency-band encoding information;

a second spectrum calculating section that calculates a second spectrum from the original signal;

a first parameter calculating section that calculates a first parameter indicating a degree of similarity between the first spectrum and a high frequency band of the second spectrum;

a second parameter calculating section that calculates a second parameter indicating a fluctuation component between the first spectrum and the high frequency band of the second spectrum; and

an encoding section that encodes the calculated first parameter and second parameter as the high-frequency-band encoding information.

2. The encoding apparatus according to claim 1, wherein the first parameter calculating section outputs a parameter indicating a characteristic of a filter as the first parameter using the filter having the first spectrum as an internal state.

3. The encoding apparatus according to claim 1, wherein the second parameter calculating section has a spectrum residual shape codebook recorded with a plurality of spectrum residual candidates and outputs a code of the spectrum residual as the second parameter.

4. The encoding apparatus according to claim 1, further comprising a residual component encoding section that encodes a residual component between the first spectrum and a low frequency band of the second spectrum,

wherein the first parameter calculating section and the second parameter calculating section calculate the first parameter and the second parameter after improving quality of the first spectrum using the residual component encoded by the residual component encoding section.

5. The encoding apparatus according to claim 4, wherein the residual component encoding section improves both quality of the low frequency band of the first spectrum and quality of a high frequency band of the decoded spectrum obtained from the first parameter and the second parameter encoded by the encoding section.

6. The encoding apparatus according to claim 1, wherein:

the first parameter contains a lag;

the second parameter contains a spectrum residual; and

the encoding apparatus further comprises a configuration section that configures a bitstream arranged in order of the lag and the spectrum residual.

7. An encoding apparatus that generates low-frequency-band encoding information and high-frequency-band encoding information from an original signal, the encoding apparatus comprising:

a first spectrum calculating section that calculates a first spectrum of a low frequency band from a decoded signal of the low-frequency-band encoding information;

a second spectrum calculating section that calculates a second spectrum from the original signal;

a parameter calculating section that calculates a parameter indicating a degree of similarity between the first spectrum and a high frequency band of the second spectrum;

a parameter encoding section that encodes the calculated parameter as the high-frequency-band encoding information; and

a residual component encoding section that encodes a residual component between the first spectrum and a low frequency band of the second spectrum,

wherein the parameter calculating section calculates the parameter after improving quality of the first spectrum using the residual component encoded by the residual component encoding section.

8. A decoding apparatus comprising:

a spectrum acquiring section that acquires a first spectrum corresponding to a low frequency band;

a parameter acquiring section that respectively acquires a first parameter that is encoded as high-frequency-band encoding information and indicates a degree of similarity between the first spectrum and a high frequency band of a second spectrum corresponding to an original signal, and a second parameter that is encoded as high-frequency-band encoding information and indicates a fluctuation component between the first spectrum and the high frequency band of the second spectrum; and

a decoding section that decodes the second spectrum using the acquired first parameter and second parameter.

9. An encoding method for generating low-frequency-band encoding information and high-frequency-band encoding information from an original signal, the encoding method comprising:

a first spectrum calculating step of calculating a first spectrum of a low frequency band from a decoded signal of the low-frequency-band encoding information;

a second spectrum calculating step of calculating a second spectrum from the original signal;

a first parameter calculating step of calculating a first parameter indicating a degree of similarity between the first spectrum and a high frequency band of the second spectrum;

a second parameter calculating step of calculating a second parameter indicating a fluctuation component between the first spectrum and the high frequency band of the second spectrum; and

an encoding step of encoding the calculated first parameter and second parameter as the high-frequency-band encoding information.

10. A decoding method comprising:

a spectrum acquiring step of acquiring a first spectrum corresponding to a low frequency band;

a parameter acquiring step of respectively acquiring a first parameter that is encoded as high-frequency-band encoding information and indicates a degree of similarity between the first spectrum and a high frequency band of a second spectrum corresponding to an original signal, and a second parameter that is encoded as high-frequency-band encoding information and indicates a fluctuation component between the first spectrum and the high frequency band of the second spectrum; and

a decoding step of decoding the second spectrum using the acquired first parameter and second parameter.