ENCODING DEVICE, DECODING DEVICE AND METHOD FOR BOTH

• US 20120209596A1
• Filed: 10/19/2010
• Published: 08/16/2012
• Est. Priority Date: 10/20/2009
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Oshikiri, Masahiro
• Granted Patent: US 8,977,546 B2
• Time in Patent Office: Days
• US Class Current: 704/201
• CPC Class Codes: G10L 19/02 using spectral analysis, e.g. transform vocoders or subband vocoders
• CPC Class Codes: G10L 19/025 Detection of transients or attacks for time/frequency resolution switching
• CPC Class Codes: G10L 19/06 Determination or coding of the spectral characteristics, e.g. of the short-term prediction coefficients
• 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

Disclosed are an encoding device and a decoding device which suppress the occurrence of pre-echo artifacts and post-echo artifacts caused by a high layer having a low temporal resolution, and which implement high subjective quality encoding and decoding. An encoding device (100) carries out scalable coding comprising a low layer, and a high layer having a lower temporal resolution than that of the low layer. A start point detection unit (or end point detection unit) (150) determines the start point (or end point) of sections of the decoded low layer signal which have audio, and when the start point (or end point) is determined, a second layer encoding unit (160) selects a bandwidth to be excluded from encoding on the basis of the spectral energy from the decoded first layer signal, excludes the selected bandwidth, and encodes an error signal.

Claims

1. A coding apparatus for scalable coding including:

a lower layer; and

a higher layer having temporal resolution lower than temporal resolution of the lower layer, the coding apparatus comprising;

a lower layer coding section that encodes an input signal to obtain a lower layer encoded signal;

a lower layer decoding section that decodes the lower layer encoded signal to obtain a lower layer decoded signal;

an error signal generating section that obtains an error signal between the input signal and the lower layer decoded signal;

a determining section that determines a start point or an end point of an active speech portion in the lower layer decoded signal; and

a higher layer coding section that selects, if the determining section determines the start point or the end point, a band to be excluded from coding target bands, excludes the selected band to encode the error signal, and obtains a higher layer encoded signal.

2. The coding apparatus according to claim 1, wherein

the higher layer coding section selects the band to be excluded, on a basis of energy of a spectrum of the lower layer decoded signal or energy of a spectrum of the error signal.

3. The coding apparatus according to claim 1 wherein

the higher layer coding section selects, as the band to be excluded, a band whose energy of a spectrum of the lower layer decoded signal or energy of a spectrum of the error signal is the smallest or is smaller than a predetermined threshold value.

5. The coding apparatus according to claim 1, wherein:

the lower layer coding section performs coding using LPC coefficients; and

the higher layer coding section selects, as the band to be excluded, a band having small energy of a spectrum of the LPC coefficients.

6. A communication terminal apparatus comprising a coding apparatus according to claim 1.

7. A base station apparatus comprising a coding apparatus according to claim 1.

4. The coding apparatus according to claim wherein

the higher layer coding section calculates a perceptual masking threshold value using the lower layer decoded signal, and selects, as the band to be excluded, a band whose energy of a spectrum of the perceptual masking threshold value is the smallest or is smaller than a predetermined threshold value.

8. A decoding apparatus for decoding a lower layer encoded signal and a higher layer encoded signal that are encoded by a coding apparatus for scalable coding including:

a lower layer; and

a higher layer having temporal resolution lower than temporal resolution of the lower layer, the decoding apparatus comprising;

a lower layer decoding section that decodes the lower layer encoded signal to obtain a lower layer decoded signal;

a higher layer decoding section that excludes or processes a band selected on a basis of a preset condition to decode the higher layer encoded signal, and obtains a decoded error signal; and

an adding section that adds the lower layer decoded signal to the decoded error signal to obtain a decoded signal.

9. The decoding apparatus according to claim 8, wherein

the higher layer decoding section selects a band on a basis of energy of a spectrum of the lower layer decoded signal, excludes the selected band to decode the higher layer encoded signal, and obtains the decoded error signal.

10. The decoding apparatus according to claim 9, wherein

the higher layer decoding section excludes a band whose energy of the spectrum of the lower layer decoded signal is the smallest or is smaller than a predetermined threshold value, and decodes the higher layer encoded signal.

11. The decoding apparatus according to claim 9, wherein

the higher layer decoding section calculates a perceptual masking threshold value using the lower layer decoded signal, excludes a band whose energy of a spectrum of the perceptual masking threshold value is the smallest or is smaller than a predetermined threshold value, and decodes the higher layer encoded signal.

12. The decoding apparatus according to claim 9, wherein

the selected band is included in the higher layer encoded signal.

13. The decoding apparatus according to claim 8, further comprising a determining section that determines a start point or an end point of an active speech portion in the lower layer decoded signal, wherein

the higher layer decoding section selects, if the determining section determines the start point or the end point, a band to be excluded from decoding target bands on a basis of energy of a spectrum of the lower layer decoded signal, excludes the selected band, and decodes the higher layer encoded signal.

14. The decoding apparatus according to claim 8, further comprising a determining section that determines a start point or an end point of an active speech portion in the lower layer decoded signal, wherein

the higher layer decoding section selects, if the determining section determines the start point or the end point, a band for which decoding transform coefficients of the decoded error signal are attenuated, and attenuates the decoding transform coefficients of the decoded error signal for the selected band to obtain the decoded error signal.

15. The decoding apparatus according to claim 14, wherein

the higher layer decoding section selects the band for which the decoding transform coefficients of the decoded error signal are attenuated, on a basis of energy of a spectrum of the lower layer decoded signal.

16. A communication terminal apparatus comprising a decoding apparatus according to claim 8.

17. A base station apparatus comprising a decoding apparatus according to claim 8.

18. A coding method for scalable coding including:

a lower layer; and

a higher layer having temporal resolution lower than temporal resolution of the lower layer, the coding method comprising;

a lower layer coding step of encoding an input signal to obtain a lower layer encoded signal;

a lower layer decoding step of decoding the lower layer encoded signal to obtain a lower layer decoded signal;

an error signal generating step of obtaining an error signal between the input signal and the lower layer decoded signal;

a determining step of determining a start point or an end point of an active speech portion in the lower layer decoded signal; and

a higher layer coding step of selecting, if the start point or the end point is determined in the determining step, a band to be excluded from coding target bands, excluding the selected band to encode the error signal, and obtaining a higher layer encoded signal.

19. A decoding method for decoding a lower layer encoded signal and a higher layer encoded signal that are encoded by a coding method for scalable coding including:

a lower layer; and

a higher layer having temporal resolution lower than temporal resolution of the lower layer, the decoding method comprising;

a lower layer decoding step of decoding the lower layer encoded signal to obtain a lower layer decoded signal;

a higher layer decoding step of excluding or processing a band selected on a basis of a preset condition to decode the higher layer encoded signal, and obtaining a decoded error signal; and

an adding step of adding the lower layer decoded signal to the decoded error signal to obtain a decoded signal.