Encoding device and decoding device

• US 20030195742A1
• Filed: 04/09/2003
• Published: 10/16/2003
• Est. Priority Date: 04/11/2002
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Norimatsu, Takeshi, Tanaka, Naoya, Tsushima, Mineo
• Granted Patent: US 7,269,550 B2
• Time in Patent Office: Days
• US Class Current: 704/205
• CPC Class Codes: G10L 19/02 using spectral analysis, e.g. transform vocoders or subband vocoders
• CPC Class Codes: G10L 19/0208 Subband vocoders
• CPC Class Codes: G10L 19/0212 using orthogonal transformation

Abstract

An encoding device (200) includes: a time characteristic extracting unit (203) that specifies a band for a part of a frequency spectrum based on a characteristic of an audio input signal in a time domain; a time transforming unit (204) that transforms a signal in the specified band to a signal according to frequency-time transform; and an encoded data stream generating unit (205) that encodes the signal obtained by the time transforming unit (204) and at least a part of the frequency spectrum, and generates an output encoded data stream from the encoded signal and the encoded frequency spectrum.

Claims

1. An encoding device that encodes a signal in a frequency domain obtained by transforming an input original signal according to time-frequency transformation, and generates an output signal comprising:

a first band specifying unit operable to specify a band for a part of a frequency spectrum based on a characteristic of the input original signal;

a time transforming unit operable to transform a signal in the specified band to a signal according to frequency-time transformation; and

an encoding unit operable to encode the signal obtained by the time transforming unit and at least a part of the frequency spectrum, and generate an output signal from the encoded signal and the encoded frequency spectrum.

2. The encoding device according to claim 1,

wherein the time transforming unit transforms the signal in the specified band to a signal indicating a temporal change of a frequency component on a time same as the frequency spectrum according to the frequency-time transformation.

3. The encoding device according to claim 2,

wherein the encoding device further includes a time domain approximating unit operable to specify two or more bands of the frequency spectrum, and approximate, using a signal indicating a temporal change of a frequency component contained in one of the specified bands, a signal indicating a temporal change of a frequency component in other specified band, and

the encoding unit encodes the signal used for the approximation for the band specified by the time domain approximating unit.

4. The encoding device according to claim 3,

wherein the time domain approximating unit generates data that specifies the band used for the approximation and the band approximated in the frequency spectrum.

5. The encoding device according to claim 4,

wherein the time domain approximating unit further generates data that indicates a gain of the signal used for the approximation for the signal approximated.

6. The encoding device according to claim 5,

wherein the encoding unit encodes, in stead of the approximated signal, the data that specifies the band used for the approximation and the data that indicates the gain, which are generated by the time domain approximating unit.

7. The encoding device according to claim 1,

wherein the first band specifying unit specifies a frequency band for a part having a big change in average energy of the input original signal.

8. The encoding device according to claim 1,

wherein the encoding device further includes a second band specifying unit operable to specify a band for a part of the frequency spectrum based on a characteristic of the frequency spectrum, and

the time transforming unit transforms a signal of the specified band to a signal according to the frequency-time transformation.

9. The encoding device according to claim 8,

wherein the encoding device further includes a frequency domain approximating unit operable to specify two or more bands contained in the frequency spectrum, and approximates, using a frequency spectrum of one of the specified bands, a frequency spectrum of other band, and

the encoding unit encodes the frequency spectrum used for the approximation for the band specified by the frequency domain approximating unit.

10. The encoding device according to claim 9,

wherein the frequency domain approximating unit generates data that specifies the band used for the approximation and the band approximated in the frequency spectrum.

11. The encoding device according to claim 10,

wherein the frequency domain approximating unit further generates data that indicates a gain of the frequency spectrum used for the approximation for the frequency spectrum approximated.

12. The encoding device according to claim 11,

wherein the encoding unit encodes, in stead of the approximated frequency spectrum, the data that specifies the band used for the approximation and the data that indicates the gain, which are generated by the frequency domain approximating unit.

13. The encoding device according to claim 8,

wherein the second band specifying unit specifies a band having wide spread of frequency spectral coefficients in the frequency spectrum.

14. A decoding device that decodes an encoded data stream obtained by encoding an input original signal, and outputs a frequency spectrum, comprising:

a decoding unit operable to extract a part of the encoded data stream contained in the input encoded data stream, and decode the extracted encoded data stream;

a frequency transforming unit operable to transform a signal obtained by decoding the extracted encoded data stream to a frequency spectrum; and

a composing unit operable to compose a frequency spectrum, which is obtained by decoding an encoded data stream extracted from other part of the input encoded data stream, and the frequency spectrum, which is obtained by the frequency transforming unit, on a frequency axis.

15. The decoding device according to claim 14,

wherein the frequency spectrum obtained by the frequency transforming unit and the frequency spectrum obtained by decoding the encoded data stream extracted from other part of the encoded data stream are a frequency spectrum that indicates a signal on a same time for the same input original signal.

16. The decoding device according to claim 15,

wherein the decoding device further includes a time approximating unit operable to approximate a band, which indicated by the extracted encoded data stream, by a signal decoded from an encoded data stream in other band, and

the frequency transforming unit transforms the approximated signal to a frequency spectrum.

17. The decoding device according to claim 16,

wherein the time approximating unit specifies a band of the signal, which is used for the approximation of the band indicated by the encoded data stream, according to data contained in the extracted encoded data stream, and executes the approximation using the signal of the specified band.

18. The decoding device according to claim 17,

wherein the time approximating unit further approximates the band by reading a gain of the signal used for the approximation for the signal approximated from data contained in the extracted encoded data stream, and by adjusting an amplitude of the signal in the specified band using the read gain.

19. The encoding device according to claim 17,

wherein the time approximating unit specifies a band already transformed to a frequency spectrum, transforms the frequency spectrum of the specified band to a signal according to frequency-time transformation, and approximates a band indicated by the extracted encoded data stream using the signal obtained by the transformation.

20. The encoding device according to claim 16,

wherein the decoding device further includes a frequency approximating unit operable to approximate the band, which is indicated by the extracted encoded data stream, by a frequency spectrum decoded from an encoded data stream in other band, and the composing unit further composes the frequency spectrum approximated by the frequency approximating unit on the frequency axis, in addition to the frequency spectrum obtained by decoding the encoded data stream extracted from other part of the input encoded data stream, and the frequency spectrum obtained by the frequency transforming unit.

21. The decoding device according to claim 20,

wherein the frequency approximating unit specifies a band of the frequency spectrum used for the approximation of the band indicated by the encoded data stream, according to data contained in the extracted encoded data stream, and executes the approximation using the frequency spectrum of the specified band.

22. The decoding device according to claim 21,

wherein the frequency approximating unit further approximates the band by reading a gain of the frequency spectrum used for the approximation for the approximated frequency spectrum from the data contained in the extracted encoded data stream, and by adjusting an amplitude of the frequency spectrum in the specified band using the read gain.

23. An encoding method for encoding a signal in a frequency domain obtained by transforming an input original signal according to time-frequency transformation, and generating an output signal, including:

a first band specifying step for specifying a band for a part of a frequency spectrum based on a characteristic of the input original signal;

a time transforming step for transforming a signal of the specified band to a signal according to frequency-time transformation; and

an encoding step for encoding the signal obtained by the time transforming step and at least a part of the frequency spectrum, and generating an output signal from the encoded signal and the encoded frequency spectrum.

24. A decoding method for decoding an encoded data stream obtained by encoding an input original signal, and outputting a frequency spectrum, including:

a decoding step for extracting a part of the encoded data stream contained in the input encoded data stream, and decoding the extracted encoded data stream;

a frequency transforming step for transforming a signal obtained by decoding the extracted encoded data stream to a frequency spectrum; and

a composing step for composing a frequency spectrum, which is obtained by decoding an encoded data stream extracted from other part of the input encoded data stream, and the frequency spectrum, which is obtained by the frequency transforming step, on a frequency axis.

25. A program for encoding a signal in a frequency domain obtained by transforming an input original signal according to time-frequency transformation, and generating an output signal, the program having the computer execute:

a first band specifying step for specifying a band for a part of a frequency spectrum based on a characteristic of the input original signal;

a time transforming step for transforming a signal of the specified band to a signal according to frequency-time transformation; and

an encoding step for encoding the signal obtained by the time transforming step and at least a part of the frequency spectrum, and generating an output signal from the encoded signal and the encoded frequency spectrum.

26. A program for decoding an encoded data stream obtained by encoding an input original signal, and outputting a frequency spectrum, the program having the computer execute:

a decoding step for extracting a part of the encoded data stream contained in the input encoded data stream, and decoding the extracted encoded data stream;

a frequency transforming step for transforming a signal obtained by decoding the extracted encoded data stream to a frequency spectrum; and

a composing step for composing a frequency spectrum, which is obtained by decoding an encoded data stream extracted from other part of the input encoded data stream, and the frequency spectrum, which is obtained by the frequency transforming step, on a frequency axis.