SPEECH AUDIO ENCODING DEVICE, SPEECH AUDIO DECODING DEVICE, SPEECH AUDIO ENCODING METHOD, AND SPEECH AUDIO DECODING METHOD

• US 20150294673A1
• Filed: 11/01/2013
• Published: 10/15/2015
• Est. Priority Date: 11/05/2012
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Inventors: Kawashima, Takuya, Oshikiri, Masahiro
• Granted Patent: US 9,679,576 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G10L 19/002 Dynamic bit allocation for perceptual audio coders G10L19/032
• CPC Class Codes: G10L 19/02 using spectral analysis, e.g. transform vocoders or subband vocoders
• CPC Class Codes: G10L 19/0204 using subband decomposition
• CPC Class Codes: G10L 19/0212 using orthogonal transformation
• CPC Class Codes: G10L 19/032 Quantisation or dequantisation of spectral components
• 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
• CPC Class Codes: G10L 21/038 using band spreading techniques

Abstract

By the present invention, the number of encoding bits allocated to encoding of extended-band spectrum is reduced while degradation of sound quality in the extended band is suppressed. A band compression unit creates combinations of sub-band spectra in pairs of two samples each in order from a low-range side in a band compression target sub-band, selects a spectrum having a large absolute-value amplitude among the combinations, and arranges the selected spectrum close to the low-range side on a frequency axis. A number-of-units recalculation unit redistributes bits saved in the sub-band for which band compression was performed to a low range outside the extended band, and redistributes the number of units on the basis of the redistributed bits.

Claims

1-17. -17. (canceled)

18. A speech/audio coding apparatus comprising:

a time/frequency transformation section that transforms a time-domain speech input signal into a frequency-domain spectrum;

a dividing section that divides the spectrum into a plurality of bands;

a limited band setting section that limits, for each band resulting from the division, when a spectrum with maximum amplitude in a preceding frame and a spectrum with maximum amplitude in a current frame are within a predetermined range, a band peripheral to the spectrum with the maximum amplitude in the preceding frame to be a coding target band; and

a transform coding section that encodes a spectrum limited as the coding target band.

19. The speech/audio coding apparatus according to claim 18, further comprising a storage section that stores information on a spectrum with maximum amplitude in the coding target band, wherein the limited band setting section searches for a band of the current frame based on a stored position of the spectrum with maximum amplitude in a preceding frame.

20. The speech/audio coding apparatus according to claim 18, wherein the limited band setting section outputs a band limitation flag indicating whether or not to limit a band.

21. The speech/audio coding apparatus according to claim 18, wherein the limited band to be limited as the coding target band has a width narrower than a normal bandwidth.

22. A speech/audio decoding apparatus comprising:

a code demultiplexing section that demultiplexes received coded data into energy coded data, transform-coded data, and a band limitation flag indicating whether or not to limit a band to be encoded, for each band;

a band-limit detection section that detects whether or not to limit a band for each band, based on the band limitation flag and that outputs information on a band-limited band obtained from the transform-coded data; and

a transform coding/decoding section that identifies a position of a spectrum with maximum amplitude in a band of a current frame using position information of a spectrum with maximum amplitude of a preceding frame included in the information on the band-limited band and that decodes the transform coded data for each band.

23. A speech/audio coding method comprising:

performing a time/frequency transformation for transforming a time-domain speech input signal into a frequency-domain spectrum;

dividing the spectrum into a plurality of bands;

limiting, for each band resulting from the division within an extended band, when a spectrum with maximum amplitude in a preceding frame and a spectrum with maximum amplitude in a current frame are within a predetermined range, a band peripheral to the spectrum with the maximum amplitude in the preceding frame to be a coding target band; and

encoding a spectrum limited as the coding target band.

24. The speech/audio coding method according to claim 23, further comprising storing information on a spectrum with maximum amplitude in the coding target band and searching for a band of the current frame based on a stored position of the spectrum with maximum amplitude in a preceding frame.

25. The speech/audio coding method according to claim 23, further comprising outputting a band limitation flag indicating whether or not to limit a band.

26. The speech/audio coding method according to claim 23, wherein the limited band to be limited as the coding target band has a width narrower than a normal bandwidth.

27. A speech/audio decoding method comprising:

demultiplexing received coded data into energy coded data, transform-coded data, and a band limitation flag indicating whether or not to limit a band to be encoded, for each band;

detecting whether or not to limit a band for each band, based on the band limitation flag and outputting information on a band-limited band obtained from the transform-coded data; and

identifying a position of a spectrum with maximum amplitude in a band of a current frame using position information of a spectrum with maximum amplitude of a preceding frame included in the information on the band-limited band and decoding the transform coded data for each band.