Encoding device, decoding device, and system thereof

• US 20030093264A1
• Filed: 11/06/2002
• Published: 05/15/2003
• Est. Priority Date: 11/14/2001
• 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: Ishikawa, Tomokazu, Miyasaka, Shuji, Sawada, Yoshiaki
• Granted Patent: US 7,260,540 B2
• Time in Patent Office: Days
• US Class Current: 704/205
• CPC Class Codes: G10L 19/18 Vocoders using multiple modes
• CPC Class Codes: G10L 19/24 Variable rate codecs, e.g. for generating different qualities using a scalable representation such as hierarchical encoding or layered encoding

Abstract

A decoding device (30a) comprises a narrow-band decoding unit (31) operable to reproduce a PCM signal (P1) from a narrow-band bit stream included in a wide-band bit stream (S0), a wide-band decoding unit (32) operable to reproduce a PCM signal (P2) having a frequency band which is wider than that of the PCM signal (P1) reproduced by the narrow-band decoding unit (31) from the narrow-band bit stream and a band expanding bit stream included in the wide band bit stream (S0) and a selecting unit (34) operable to select either the PCM signal (P1) reproduced by the narrow-band decoding unit (31) or the PCM signal (P2) reproduced by the wide-band decoding unit (32), and to output the selected sound digital signal.

Claims

1. A decoding device that decodes an encoded signal made up of a first bit stream which is an encoded sound digital signal and of a second bit stream which is an encoded band expansion information used for expanding a reproduction band of the sound digital signal, the decoding device comprising:

a first reproducing unit operable to reproduce a first sound digital signal from the first bit stream;

a second reproducing unit operable to reproduce a second sound digital signal having a frequency band which is wider than that of the first sound digital signal reproduced by the first reproducing unit from the first bit stream and the second bit stream; and

a selecting unit operable to select either the first sound digital signal reproduced by the first reproducing unit or the second sound digital signal reproduced by the second reproducing unit, and to output the selected sound digital signal.

2. The decoding device according to claim 1 further comprising a mode setting unit operable to notify the selecting unit of mode information specifying either a first mode or a second mode,

wherein the selecting unit selects and outputs the first sound digital signal reproduced by the first reproducing unit when the mode information notified by the mode setting unit indicates the first mode, and selects and outputs the second sound digital signal reproduced by the second reproducing unit when the mode information notified by the mode setting unit indicates the second mode.

3. The decoding device according to claim 2,

wherein the mode setting unit generates mode information specifying either the first mode or the second mode based on an user instruction, and notifies the selecting unit of the mode information.

4. The decoding device according to claim 2,

wherein the mode setting unit generates mode information specifying either the first mode or the second mode based on a type of the sound digital signal included in the first bit stream, and notifies the selecting unit of the mode information.

5. The decoding device according to claim 4,

wherein the mode setting unit generates mode information specifying the second mode when the type of the sound digital signal included in the first bit stream is music and notifies the selecting unit of the mode information, and generates mode information specifying the first mode when the type of the sound digital signal included in the first bit stream is not music and notifies the selecting unit of the mode information.

6. The decoding device according to claim 2,

wherein the mode setting unit generates mode information specifying either the first mode or the second mode according to a state of an apparatus having the decoding device, and notifies the selecting unit of the mode information.

7. The decoding device according to claim 6, wherein the mode setting unit generates mode information specifying the first mode when an battery energy level of the apparatus is at or below a certain value and notifies the selecting unit of the mode information, and generates mode information specifying the second mode when a battery energy level of the apparatus is over a certain value and notifies the selecting unit of the mode information.

8. The decoding device according to claim 2,

wherein the mode setting unit further notifies the second reproducing unit of the mode information, and

the second reproducing unit stops reproduction from the second bit stream to the second sound digital signal when the mode information notified by the mode setting unit indicates the first mode.

9. The decoding device according to claim 1,

wherein the first reproducing unit has:

a first separating unit operable to separate the first bit stream from the encoded signal;

a first converting unit operable to convert the first bit stream separated by the first separating unit to an intermediate signal; and

a second converting unit operable to convert the intermediate signal acquired as a result of the conversion in the first converting unit to the first sound digital signal, and

the second reproducing unit has a second separating unit operable to separate the second bit stream from the encoded signal, and reproduces the second sound digital signal using band expansion information included in the second bit stream which is separated by the second separating unit and using the intermediate signal acquired as a result of the conversion in the first converting unit.

10. The decoding device according to claim 9,

wherein the intermediate signal is information indicating a frequency spectrum.

11. The decoding device according to claim 10,

wherein the second reproducing unit further has:

a wide-band spectrum generating unit operable to generate a wider frequency spectrum than the frequency spectrum from the frequency spectrum information acquired by the first converting unit according to the band expansion information; and

a wide-band sound digital signal generating unit operable to generate a sound digital signal in the wide band from the generated frequency spectrum and from the frequency spectrum acquired by the first converting unit.

12. The decoding device according to claim 11 further comprising a mode setting unit operable to notify the selecting unit of mode information specifying either the first mode or the second mode,

wherein the selecting unit selects and outputs the sound digital signal reproduced by the first reproducing unit when the mode information notified by the mode setting unit indicates the first mode, and selects and outputs the sound digital signal reproduced by the second reproducing unit when the mode information notified by the mode setting unit indicates the second mode.

13. The decoding device according to claim 12,

wherein the mode setting unit further notifies the second reproducing unit of the mode information, and

the second reproducing unit has at least either the wide-band spectrum generating unit stop generation of the frequency spectrum or the wide-band sound digital signal generating unit stop generation of the second sound digital signal.

14. The decoding device according to claim 9,

wherein the intermediate signal is a time domain signal.

15. The decoding device according to claim 1,

wherein the first bit stream and the second bit stream are alternately multiplexed per specific frame, and

the second reproducing unit has the second separating unit operable to separate the second bit stream from the encoded signal.

16. The decoding device according to claim 15,

wherein a code amount of the band expansion information is variable per frame, and

size information indicating a size of the codes is multiplexed into the second bit stream, and

the second separating unit separates the second bit stream from the encoded signal according to the size information included in the second bit stream.

17. The decoding device according to claim 16,

wherein the size information is placed at a top of the second bit stream, and

the second separating unit specifies a size of the codes for the band expansion information according to the size information included at the top of the second bit stream, and separates the second bit stream from the encoded signal based on the specified size.

18. The decoding device according to claim 17,

wherein the size information is N bits or (N+M) bits indicating the size of the codes for the band expansion information, and

the second separating unit specifies the size of the codes for the band expansion information according to the N or (N+M) bits included at the top of the second bit stream, and separates the second bit stream from the encoded signal according to the specified size.

19. The decoding device according to claim 18,

wherein N bits in the (N+M) bits indicates a maximum value which N bits can represent, and the M bits indicates a size of codes exceeding a size indicated by the maximum value, out of the code amount of the band expansion information.

20. An encoding device that encodes a sound digital signal, the encoding device comprising:

a first encoding unit operable to encode an inputted sound digital signal;

a second encoding unit operable to generate to encode band expansion information used for expanding a reproduction band of the signal encoded by the first encoding unit from the inputted sound digital signal;

a size calculating unit operable to calculate a size of the encoded signal acquired by the second encoding unit;

a first multiplexing unit operable to multiplex information indicating the size calculated by the size calculating unit and the encoded signal acquired by the second encoding unit; and

a second multiplexing unit operable to multiplex a first bit stream acquired by the first encoding unit and a second bit stream acquired by the first multiplexing unit.

21. The encoding device according to claim 20,

wherein the second multiplexing unit alternately multiplexes the first bit stream and the second bit stream per specific frame.

22. The encoding device according to claim 21,

wherein the first multiplexing unit multiplexes the information indicating the size and the encoded signal in a manner in which the information indicating the size is placed at the top of the second bit stream.

23. The encoding device according to claim 22,

wherein the information indicating the size is N bits or (N+M) bits indicating a size of codes for the band expansion information, and

the size calculating unit determines whether to use N bits or (N+M) bits according to whether or not the size of the codes for the band expansion information is smaller than a maximum value represented by N bits.

24. The encoding device according to claim 23,

wherein N bits in the (N+M) bits indicates the maximum value which N bits can represent, and the M bits indicates a size of codes exceeding a size indicated by the maximum value, out of the code amount of the band expansion information.

25. A communication system made up of an encoding device and a decoding device which are connected by a transmission line, the communication system,

wherein the encoding device comprising:

a first encoding unit operable to encode an inputted sound digital signal;

a second encoding unit operable to generate to encode band expansion information used for expanding a reproduction band of the signal encoded by the first encoding unit from the inputted sound digital signal;

a size calculating unit operable to calculate a size of the encoded signal acquired by the second encoding unit;

a first multiplexing unit operable to multiplex information indicating the size calculated by the size calculating unit and the encoded signal acquired by the second encoding unit; and

a second multiplexing unit operable to multiplex a first bit stream acquired by the first encoding unit and a second bit stream acquired by the first multiplexing unit, and

the decoding device comprising;

a first reproducing unit operable to reproduce a first sound digital signal from the first bit stream;

a second reproducing unit operable to reproduce a second sound digital signal having a frequency band which is wider than that of the first sound digital signal reproduced by the first reproducing unit from the first bit stream and the second bit stream; and

a selecting unit operable to select either the first sound digital signal reproduced by the first reproducing unit or the second sound digital signal reproduced by the second reproducing unit and to output the selected sound digital signal.

26. A decoding method for decoding an encoded signal made up of a first bit stream which is an encoded sound digital signal and of a second bit stream which is an encoded band expansion information used for expanding a reproduction band of the sound digital signal, the decoding method includes:

a first reproducing step for reproducing a first sound digital signal from the first bit stream;

a second reproducing step for reproducing a second sound digital signal having a frequency band which is wider than that of the first sound digital signal reproduced by the first reproducing unit from the first bit stream and the second bit stream; and

a selecting step for selecting either the first sound digital signal reproduced at the first reproducing step or the second sound digital signal reproduced at the second reproducing step and for outputting the selected sound digital signal.

27. An encoding method for encoding a sound digital signal, the encoding method includes:

a first encoding step for encoding an inputted sound digital signal;

a second encoding step for generating to encode band expansion information used for expanding a reproduction band of the signal encoded at the first encoding step from the inputted sound digital signal;

a size calculating step for calculating a size of the encoded signal acquired at the second encoding step;

a first multiplexing step for multiplexing information indicating the size calculated at the size calculating step and the encoded signal acquired at the second encoding step; and

a second multiplexing step for multiplexing a first bit stream acquired at the first encoding step and a second bit stream acquired at the first multiplexing step.

28. A communication method for a system made up of an encoding device and a decoding device which are connected by a transmission line, the communication method,

wherein the encoding device includes:

a first encoding step for encoding an inputted sound digital signal;

a second encoding step for generating to encode band expansion information used for expanding a reproduction band of the signal encoded at the first encoding step from the inputted sound digital signal;

a size calculating step for calculating a size of the encoded signal acquired at the second encoding step;

a first multiplexing step for multiplexing information indicating the size calculated at the size calculating step and the encoded signal acquired at the second encoding step; and

a second multiplexing step for multiplexing a first bit stream acquired at the first encoding step and a second bit stream acquired at the first multiplexing step, and

the decoding device includes;

a first reproducing step for reproducing a first sound digital signal from the first bit stream;

a second reproducing step for reproducing a second sound digital signal having a frequency band which is wider than that of the first sound digital signal reproduced at the first reproducing step from the first bit stream and the second bit stream; and

a selecting step for selecting either the first sound digital signal reproduced at the first reproducing step or the second sound digital signal reproduced at the second reproducing step and for outputting the selected sound digital signal.

29. A program for decoding an encoded signal made up of a first bit stream which is an encoded sound digital signal and of a second bit stream which is an encoded band expansion information used for expanding a reproduction band of the sound digital signal, the program includes:

a first reproducing step for reproducing a first sound digital signal from the first bit stream;

a second reproducing step for reproducing a second sound digital signal having a frequency band which is wider than that of the first sound digital signal reproduced by the first reproducing unit from the first bit stream and the second bit stream; and

a selecting step for selecting either the first sound digital signal reproduced at the first reproducing step or the second sound digital signal reproduced at the second reproducing step and for outputting the selected sound digital signal.

30. A program for encoding a sound digital signal, the program includes:

a first encoding step for encoding an inputted sound digital signal;

a second encoding step for generating to encode band expansion information used for expanding a reproduction band of the signal encoded at the first encoding step from the inputted sound digital signal;

a size calculating step for calculating a size of the encoded signal acquired at the second encoding step;

a first multiplexing step for multiplexing information indicating the size calculated at the size calculating step and the encoded signal acquired at the second encoding step; and

a second multiplexing step for multiplexing a first bit stream acquired at the first encoding step and a second bit stream acquired at the first multiplexing step.

31. A recording medium in which an encoded signal decoded by a decoding device is stored,

wherein the decoding device comprises:

a first reproducing unit operable to reproduce a first sound digital signal from the first bit stream;

a second reproducing unit operable to reproduce a second sound digital signal having a frequency band which is wider than that of the first sound digital signal reproduced by the first reproducing unit from the first bit stream and a second bit stream included in the encoded signal; and

a selecting unit operable to select either the first sound digital signal reproduced by the first reproducing unit or the second sound digital signal reproduced by the second reproducing unit, and to output the selected sound digital signal,

the second reproducing unit has a second separating unit operable to separate the second bit stream from the encoded signal according to size information included in the second bit stream,

the encoded signal stored in the recording medium is made up of a first bit stream which is an encoded sound digital signal and of a second bit stream which is an encoded band expansion information used for expanding a reproduction band of the sound digital signal,

the first bit stream and the second bit stream are multiplexed in each block having a specified number of frames,

a code amount of the band expansion information is variable per frame, and

said each block where the second bit stream is stored has information indicating an end position of the block at a top of each block.

32. The recording medium according to claim 31,

wherein the information indicating the end position of said each block of the second bit stream is size information of the block.

33. The recording medium according to claim 32,

wherein the size information is N bits or (N+M) bits indicating a size of codes for the band expansion information, and

a determination of either N bits or (N+M) bits is used is made according to whether or not the size of the codes for the band expansion information is smaller than a maximum value which can be represented by N bits.

34. The recording medium according to claim 33,

wherein N bits in the (N+M) bits indicates the maximum value which N bits can represent, and the M bits indicates a size of codes exceeding a size indicated by the maximum value, out of the code amount of the band expansion information.