ENCODING DEVICE AND ENCODING METHOD

• US 20100017204A1
• Filed: 02/29/2008
• Published: 01/21/2010
• Est. Priority Date: 03/02/2007
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Morii, Toshiyuki, Oshikiri, Masahiro, Yamanashi, Tomofumi
• Granted Patent: US 8,554,549 B2
• Time in Patent Office: Days
• US Class Current: 704/222
• CPC Class Codes: G10L 19/00 Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis in musical instruments G10H
• CPC Class Codes: G10L 19/005 Correction of errors induced by the transmission channel, if related to the coding algorithm
• 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 19/038 Vector quantisation, e.g. TwinVQ audio
• CPC Class Codes: G10L 19/083 the excitation function being an excitation gain G10L25/90 takes precedence
• 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 25/18 the extracted parameters being spectral information of each sub-band

Abstract

Provided is a voice encoding device which can accurately encode a spectrum shape of a signal having a strong tonality such as a vowel. The device includes: a sub-band constituting unit (151) which divides a first layer error conversion coefficient to be encoded into M sub-bands so as to generate M sub-band conversion coefficients; a shape vector encoding unit (152) which performs encoding on each of the M sub-band conversion coefficient so as to obtain M shape encoded information and calculates a target gain of each of the M sub-band conversion coefficients; a gain vector forming unit (153) which forms one gain vector by using M target gains; a gain vector encoding unit (154) which encodes the gain vector so as to obtain gain encoded information; and a multiplexing section unit (155) which multiplexes the shape encoded information with the gain encoded information.

Claims

1. An encoding apparatus comprising:

a base layer encoding section that encodes an input signal to acquire base layer encoded data;

a base layer decoding section that decodes the base layer encoded data to acquire a base layer decoded signal; and

an enhancement layer encoding section that encodes a residual signal representing a difference between the input signal and the base layer decoded signal, to acquire enhancement layer encoded data,

wherein the enhancement layer encoding section comprises;

a dividing section that divides the residual signal into a plurality of subbands;

a first shape vector encoding section that encodes the plurality of subbands to acquire first shape encoded information, and that calculates target gains of the plurality of subbands;

a gain vector forming section that forms one gain vector using the plurality of target gains; and

a gain vector encoding section that encodes the gain vector to acquire first gain encoded information.

2. The encoding apparatus according to claim 1, wherein the first shape vector encoding section encodes the plurality of subbands using a shape vector codebook formed with a plurality of shape vector candidates which include at least one pulse placed at an arbitrary frequency.

3. The encoding apparatus according to claim 2, wherein the first shape vector encoding section encodes the plurality of subbands using correlation information related to the shape vector candidate selected from the shape vector codebook.

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

the enhancement layer encoding section further comprises a range selecting section that calculates tonalities of a plurality of ranges formed using an arbitrary number of adjacent subbands and that selects one range of the strongest tonality from the plurality of ranges; and

the first shape vector encoding section, the gain vector forming section and the gain vector encoding section operate with respect to a plurality of subbands forming the selected range.

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

the enhancement layer encoding section further comprises a range selecting section that calculates average energies of a plurality of ranges formed using an arbitrary number of adjacent subbands and that selects one range of the highest average energy from the plurality of ranges; and

the first shape vector encoding section, the gain vector forming section and the gain vector encoding section operate with respect to a plurality of subbands forming the selected range.

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

the enhancement layer encoding section further comprises a range selecting section that calculates perceptual weighting energies of a plurality of ranges formed using an arbitrary number of adjacent subbands and that selects one range of the highest perceptual weighting energy from the plurality of ranges; and

the first shape vector encoding section, the gain vector forming section and the gain vector encoding section operate with respect to a plurality of subbands forming the selected range.

7. The encoding apparatus according to claim 4, wherein the range selecting section selects one of a plurality of ranges in lower bands than a predetermined frequency.

8. The encoding apparatus according to claim 4 further comprising the plurality of enhancement layers, wherein the predetermined frequency is higher in a higher layer.

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

the enhancement layer encoding section further comprises a range selecting section that forms a plurality of ranges using an arbitrary number of adjacent subbands, that forms a plurality of partial bands using an arbitrary number of ranges, that selects one range of highest average energy from each of the plurality of partial bands and that concatenates a plurality of selected ranges to make a concatenated range; and

the first shape vector encoding section, the gain vector forming section and the gain vector encoding section operate with respect to a plurality of subbands forming the selected concatenated range.

10. The encoding apparatus according to claim 9, wherein the range selecting section selects at all times a fixed range which is specified in advance, in at least one of the plurality of partial bands.

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

the enhancement layer encoding section further comprises a tonality deciding section that decides strength of tonality of the input signal; and

when the strength of the tonality of the input signal is decided to be equal to or more than a predetermined level, the enhancement layer;

divides the residual signal into the plurality of subbands;

encodes the plurality of subbands to acquire the first shape encoded information and calculates the target gains of the plurality of subbands;

forms one gain vector using the plurality of target gains; and

encodes the gain vector to acquire the first gain encoded information.

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

the base layer encoding section comprises;

a down-sampling section that down-samples the input signal to acquire a down-sampled signal; and

a core encoding section that encodes the down-sampled signal to acquire core encoded data as encoded data; and

the base layer decoding section comprises;

a core decoding section that decodes the core encoded data to acquire a core decoded signal;

an up-sampling section that up-samples the core decoded signal to acquire an up-sampled signal; and

a substituting section that substitutes noise for a high frequency band component of the up-sampled signal.

13. The encoding apparatus according to claim 1, further comprising:

a gain encoding section that encodes gains of transform coefficients of the plurality of subbands to acquire second gain encoded information;

a normalizing section that normalizes the transform coefficients of the plurality of subbands using the second decoded gains acquired by decoding the gain encoded information, to acquire a plurality of normalized shape vectors;

a second shape vector encoding section that encodes the plurality of normalized shape vectors to acquire second shape encoded information; and

a deciding section that calculates tonality of the input signal on a per frame basis, that outputs the transform coefficients of the plurality of subbands to the first shape vector encoding section when the tonality is decided to be equal to or more than the threshold, and that outputs the transform coefficients of the plurality of subbands to the gain encoding section when the tonality is decided to be less than the threshold.

14. An encoding method comprising:

dividing transform coefficients acquired by transforming an input signal in a frequency domain, into a plurality of subbands;

encoding transform coefficients of the plurality of subbands to acquire first shape encoded information and calculating target gains of the transform coefficients of the plurality of subbands;

forming one gain vector using the plurality of target gains; and

encoding the gain vector to acquire first gain encoded information.