US 8,301,439 B2 · Method and apparatus to encode/decode low bit-rate audio signal by approximiating high frequency envelope with strongly correlated low frequency codevectors

Abstract

A method of encoding a low bit-rate audio signal includes quantizing and encoding a plurality of low frequency sub-bands of an audio signal in a frequency domain, generating a codebook of codevectors using sub-bands of the audio signal spectrum, detecting an envelope of another frequency sub-band of the audio signal and quantizing and losslessly-encoding the detected envelope, selecting a codevector most similar to the higher frequency sub-band spectrum from the generated codebook's codevectors and determining its codebook codevector index, and generating a bit stream. Decoding the low bit-rate audio signal includes restoring and dividing a bit stream into a plurality of first frequency sub-bands and at least one second frequency sub-band and inversely quantizing the first frequency sub-bands in the bit stream, restoring codebook codevector index information and envelope information for the second frequency sub-band, generating a codebook of codevectors using the inversely quantized first frequency sub-bands, and restoring the second frequency sub-band using the restored codevector index information and the envelope information.

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Claims44

Dependent claims

A method of encoding a low bit-rate audio signal, the method comprising:

quantizing and encoding a plurality of first frequency sub-bands in a low frequency region of a full-band audio signal having a plurality of frequency sub-bands;
generating a codebook of codevectors using one or more of the plurality of overlapping first frequency sub-bands of the low frequency region of the full-band audio signal to vector quantize at least one high frequency sub-band or to encode at least one high frequency sub-band by perceptual noise substitution;
detecting an envelope of at least one second frequency sub-band in a high frequency region of the full-band audio signal higher than the highest low frequency sub-band and quantizing and encoding the envelope;
selecting a codevector in the first frequency sub-band codebook that is most similar to the second frequency sub-band to be encoded from the generated codebook's codevectors and determining a codebook codevector index which defines a fine structure of the first frequency sub-band to help encode the structure of the similar second frequency sub-band;
and
generating a bit stream using encoded data generated in the encoding of the first frequency sub-band, the envelope, and the determined codebook codevector index.

3 more elements

An apparatus to encode a low bit-rate audio signal, the apparatus comprising:

a low frequency quantizing/encoding unit which quantizes and encodes a plurality of first frequency sub-bands in a low frequency region of a full-band audio signal having a plurality of frequency sub-bands;
a codebook generating unit which generates a codebook of codevectors using one or more of the plurality of first frequency sub-bands of the low frequency region of the full-band audio signal to vector quantize at least one high frequency sub-band or to encode at least one high frequency sub-band by perceptual noise substitution;
an envelope quantizing/encoding unit which detects an envelope of at least one second frequency sub-band of a high frequency region of the full-band audio signal higher than the highest low frequency sub-band and quantizes and encodes the detected envelope of the second frequency sub-band;
a similarity checking unit which checks whether a codevector of the codebook having at least a predetermined similarity exists among the generated codevectors of the codebook with respect to a high frequency band to be encoded;
a codebook existence information/index encoding unit which selects a similar codevector from the codebook, determines a codebook codevector index which defines a fine structure of the first frequency sub-band if the similar codevector in the codebook exists, and encodes the determined codebook codevector index and information indicating that the similar codevector exists;
a codebook existence information encoding unit which encodes information indicating that a similar codevector in the codebook does not exist if a similar codevector in the codebook does not exist;
and
a bitstream generating unit which generates a bit stream using encoded data which are generated by the low frequency quantizing/encoding unit, the codebook existence information/index encoding unit, and the codebook existence information encoding unit.

5 more elements

An apparatus to decode a low bit-rate audio signal, the apparatus comprising:

a bit stream dividing unit which divides a bit stream into a plurality of first frequency sub-bands of a full-band audio signal having a plurality of frequency sub-bands and at least one second frequency sub-band other than the first frequency sub-bands of the full-band audio signal;
a low frequency restoring unit which decodes and inversely quantizes the first frequency sub-bands of the full-band audio signal;
a codebook existence information restoring unit which decodes information as to whether a similar codevector of a codebook exists to inversely vector quantize at least one second frequency sub-band or to decode at least one second frequency sub-band by perceptual noise substitution;
an index/envelope restoring unit which, if the similar codevector of the codebook exists, restores codebook codevector index information that defines a fine structure of the first frequency sub-band and envelope information about the second frequency sub-band to restore the similar second frequency sub-band;
a first high frequency restoring unit which generates a codebook of codevectors using the first frequency sub-band which is decoded and inversely quantizes and restores the second frequency sub-band using the restored codebook index information and the restored envelope information about the second frequency sub-band;
and
a second high frequency restoring unit which, if a similar codevector does not exist, restores the envelope information and restores the second frequency sub-band using a signal of a previous band and the restored envelope information.

4 more elements

Dependencies are inferred from the claim text.

Description6,718 words

Summary2,118 words

#This application claims the benefit of Korean Patent Application No. 10-2005-0064508, filed on Jul. 15, 2005, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.

#1. Field of the Invention

#The present general inventive concept relates to encoding and decoding of an audio signal, and more particularly, to a method and apparatus to encode/decode a low bit-rate audio signal.

Brief description of the drawings11 figures

#These and/or other aspects of the present general inventive concept will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

#FIG. 1 is a block diagram illustrating a configuration of an apparatus to encode a low bit-rate audio signal according to an embodiment of the present general inventive concept;

#FIG. 2 is a block diagram illustrating a configuration of an apparatus to encode a low bit-rate audio signal according to another embodiment of the present general inventive concept;

Detailed description4,303 words

#Reference will now be made in detail to the embodiments of the present general inventive concept, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present general inventive concept by referring to the figures.

#According to embodiments of the present general inventive concept, a codebook is generated using a low frequency component of an audio signal, and a high frequency component of the audio signal is efficiently encoded by vector quantization (VQ) using the codebook, without additional information such as envelope/noise floor/time-frequency grid.

#FIG. 1 is a block diagram illustrating a configuration of an apparatus to encode a low bit-rate audio signal according to an embodiment of the present general inventive concept. The apparatus in FIG. 1 includes a low frequency quantizing/lossless-encoding unit 110, an envelope quantizing/lossless-encoding unit 120, a codebook generating unit 130, a codebook index acquiring unit 140, an index lossless-encoding unit 150, and a bit stream generating unit 160. The apparatus of the present embodiment may further include a time/frequency (T/F) converting unit 100.

Facts

Application

11/456,946Filed 12 Jul 2006

Priority

KR 10-2005-006450815 Jul 2005

Published

US 2007/0016411 A118 Jan 2007

Granted

30 Oct 2012

Term ends

6 Jan 2029

Estimated · how

20 years from earliest known nonprovisional domestic filing plus recorded patent term adjustment, including 909 days of adjustment. Maintenance-fee lapses, terminal disclaimers and statutory extensions have not been checked. The continuity chain may be incomplete; this is not an enforceability determination.

Classification4 codes

G10L 19/02
Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals,…:…
G10L 19/0017
Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals,…:…
G10L 19/06
Using predictive techniques: determination or coding of the spectral characteristics, e.g. of the short-term prediction coefficients
G10L
Speech analysis techniques or speech synthesis

Timeline

15 Jul 2005Priority claimedKR 10-2005-0064508
12 Jul 2006Application filedUS 11/456,946
19 Sep 2006Assigned to Samsung Electronics Co., Ltd.assignment of assignor's interest
18 Jan 2007PublishedUS 2007/0016411 A1
30 Oct 2012GrantedUS 8,301,439 B2
12 Oct 2026TodayWithin its term
6 Jan 2029Term endsEstimated, includes 909 days of adjustment

Method and apparatus to encode/decode low bit-rate audio signal by approximiating high frequency envelope with strongly correlated low frequency codevectors

Life of this patent

Method and apparatus to encode/decode low bit-rate audio signal by approximiating high frequency envelope with strongly correlated low frequency codevectors

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims44

Description6,718 words

Drawings

Classification4 codes

Life of this patent

Description6,718 words