AUDIO ENCODING APPARATUS AND AUDIO ENCODING METHOD

• US 20130030796A1
• Filed: 01/13/2011
• Published: 01/31/2013
• Est. Priority Date: 01/14/2010
• Status: Abandoned Application

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Liu, Zongxian
• Application Number:
  US13/521,590
• Publication Number:
  US 20130030796A1
• Time in Patent Office: Days
• US Class Current: 704/205
• CPC Class Codes: G10L 19/0212 using orthogonal transformation
• CPC Class Codes: G10L 19/12 the excitation function being a code excitation, e.g. in code excited linear prediction [CELP] vocoders
• 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

An audio encoding apparatus that allows a decoded signal exhibiting an excellent sound quality to be obtained on a decoding side. In the audio encoding apparatus (1000A), a time-frequency transform unit (1001) uses a time-frequency transform, such as a discrete Fourier transform (DFT) or a modified discrete cosine transform (MDCT), to transform a time domain signal (S(n)) to a frequency domain signal (spectrum factor) (S(f)). A psychoacoustic model analyzing unit (1002) performs a psychoacoustic model analysis of the frequency domain signal (S(f)), thereby obtaining a masking curve. An acoustic sense weighting unit (1003) estimates, based on the masking curve, an importance degree of acoustic sense, and determines and applies the weighting factors of respective spectrum factors to the respective spectrum factors. An encoding unit (1004) encodes the frequency domain signal (S(f)) as weighted in terms of the acoustic sense. A multiplexing unit (1005) multiplexes and transmits the encoded parameters.

Claims

1. A speech coding apparatus comprising:

an estimation section that estimates respective perceptual importance levels of a plurality of spectral coefficients of different frequencies;

a calculating section that calculates respective weighting coefficients of the plurality of spectral coefficients based on the respective estimated importance levels;

a weighting section that weights each of the plurality of spectral coefficients using the respective calculated weighting coefficients; and

a coding section that encodes the plurality of weighted spectral coefficients.

2. The speech coding apparatus according to claim 1, wherein the estimation section estimates the importance level based on a perceptual masking curve determined from an input signal.

3. A speech coding apparatus that performs layer coding including at least two layers of a lower layer and a higher layer, the speech coding apparatus comprising:

a generating section that generates an error signal between a decoded signal of the lower layer and an input signal;

an estimation section that calculates a signal-to-noise ratio using the input signal and the error signal and estimates respective perceptual importance levels of a plurality of spectral coefficients of different frequencies in the error signal, based on the signal-to-noise ratio;

a calculating section that calculates respective weighting coefficients of the plurality of spectral coefficients based on the respective estimated importance levels;

a weighting section that weights each of the plurality of spectral coefficients using the respective calculated weighting coefficients; and

a coding section that encodes the plurality of weighted spectral coefficients.

4. A speech coding method comprising the steps of:

estimating respective perceptual importance levels of a plurality of spectral coefficients of different frequencies;

calculating respective weighting coefficients of the plurality of spectral coefficients based on the respective estimated perceptual importance levels;

weighting each of the plurality of spectral coefficients using the respective calculated weighting coefficients; and

encoding the plurality of weighted spectral coefficients.