PULSE ENCODING AND DECODING METHOD AND PULSE CODEC

• US 20180190304A1
• Filed: 12/22/2017
• Published: 07/05/2018
• Est. Priority Date: 06/24/2010
• Status: Active Grant

• Current Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Granted Patent: US 10,446,164 B2
• Time in Patent Office: Days
• 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 19/002 Dynamic bit allocation for perceptual audio coders G10L19/032
• CPC Class Codes: G10L 19/008 Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing
• CPC Class Codes: G10L 19/107 Sparse pulse excitation, e.g. by using algebraic codebook
• 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

In a pulse encoding and decoding method and a pulse codec, more than two tracks are jointly encoded, so that free codebook space in the situation of single track encoding can be combined during joint encoding to become code bits that may be saved. Furthermore, a pulse that is on each track and required to be encoded is combined according to positions, and the number of positions having pulses, distribution of the positions that have pulses on the track, and the number of pulses on each position that has a pulse are encoded separately, so as to avoid separate encoding performed on multiple pulses of a same position, thereby further saving code bits.

Claims

1. An audio signal encoder comprising a processor and a non-transitory computer readable medium storing instructions for execution by the processor, wherein when the instructions are executed by the processor, the processor is configured to:

obtain an audio signal;

determine number of pulses on each of T tracks of the audio signal, wherein T is an integer greater than or equal to 2;

collect statistics of pulses on multiple positions on each track, wherein the statistics of pulses on a t^th track, 0≤

t≤

T−

1, include;

(a) number of positions N_t that have pulses, (b) distribution of the N_t positions on the t^th track, (c) number of pulses on each of the N_t positions, and (d) symbols of the pulses on each of the N_t positions;

determine, for each track, a first index I1_t, wherein I1_t is a value determined according to the number of the positions N_t and wherein all possible distributions of the N_t positions on the t^th track correspond to the first index I1_t, where 0≤

t≤

T−

1;

determine, for each track, a second index I2_t, wherein the second index I2_t indicates, among the all the possible distributions of the N_t positions, a current distribution of the N_t positions on the t^th track, where 0≤

t≤

T−

1;

determine, for each track, a third index I3_t by mapping distributions in which the N_t positions have pulses to distributions that the N_t positions have −

N_t pulses, where 0≤

t≤

T−

1, wherein (a) N_t represents a total number of pulses on the t^th track, (b) all possible distributions of the −

N_t pulses on the N_t positions are arrayed according to a set order, and (c) an arrayed serial number obtained by the above arraying process is used as the third index I3_t indicating the number of pulses on a position that has a pulse;

generate a symbol index Is_t according to the symbols of the pulses on each of the N_t positions;

generate, for each track, a joint index using information of the first, the second, the third, and the fourth indexes of the track;

compare the joint index with an adjustment threshold (THR), wherein THR≤

2^Bmax−

I_max(T), I_max(T) represents an upper limit of the joint index, and Bmax represents an upper limit of the number of bits used for encoding the joint index; and

when the joint index is smaller than the THR, encode the joint index by using a first number of code bits and transmit the encoded joint index;

or

when the joint index is greater than or equal to the THR, encode the joint index plus an offset value (THR₀) by using a second number of code bits and transmit the encoded joint index plus the THR₀, wherein (a) THR≤

THR₀≤

2^Bmax−

I_max(T), (b) the first number of coding bits is smaller than the second number of coding bits, (c) the second number of coding bits is smaller than or equal to Bmax, and (d) the first number of coding bits and the second number of coding bits are both positive integers.

2. The terminal device according to claim 1, wherein the third index I3_t of the t^th track is obtained according to:

3. The terminal device according to claim 2, wherein the second index I2_t of the t^th track is obtained according to:

4. The terminal device according to claim 3, wherein the joint index Ind is obtained according to:

5. A communication system, comprising an audio signal encoder and an audio signal decoder, wherein the audio signal encoder comprises a processor and a non-transitory computer readable medium storing instructions for execution by the processor, wherein when the instructions are executed by the processor, the processor is configured to:

obtain an audio signal;

determine number of pulses on each of T tracks of the audio signal, wherein T is an integer greater than or equal to 2;

collect statistics of pulses on multiple positions on each track, wherein the statistics of pulses on the t^th track, 0≤

t≤

T−

1, include;

(a) number of positions N_t that have pulses, (b) distribution of the N_t positions on the t^th track, (c) number of pulses on each of the N_t positions, and (d) symbols of the pulses on each of the N_t positions;

determine, for each track, a first index I1_t according to the number of the positions N_t and wherein all possible distributions of the N_t positions on the t^th track correspond to the first index I1_t, where 0≤

T≤

T−

1;

determine, for each track, a second index I2_t, wherein the second index I2_t indicates, among the all possible distributions corresponding to the first index I1_t, a current distribution of the N_t positions on the t^th track, where 0≤

t≤

T−

1;

determine, for each track, a third index I3_t by mapping distributions in which the N_t positions have pulses to distributions that N_t positions have −

N_t pulses, where 0≤

t≤

T−

1, wherein (a) N_t represents a total number of pulses on the t^th track, (b) all possible distributions of the −

N_t pulses on N_t positions are arrayed according to a set order, and (c) an arrayed serial number obtained by the above arraying process is used as the third index I3_t indicating the number of pulses on a position that has a pulse;

generate a symbol index Is_t according to the symbols of the pulses on each of the N_t positions;

generate, for each track, a joint index using information of the first, second, third, and symbol indexes of the track;

compare the joint index with an adjustment threshold (THR), wherein THR≤

2^Bmax−

I_max(T), I_max(T) represents an upper limit of the joint index, and Bmax represents an upper limit of the number of bits used for encoding the joint index; and

when the joint index is smaller than the THR, encode the joint index by using a first number of code bits and transmit the encoded joint index;

or

when the joint index is greater than or equal to the THR, encode the joint index plus an offset value THR₀ by using a second number of code bits and transmit the encoded joint index, wherein (a) THR≤

THR₀≤

2^Bmax−

I_max(T), (b) the first number of coding bits is smaller than the second number of coding bits, (c) the second number of coding bots is smaller than or equal to Bmax, and (d) the first number of coding bits and the second number of coding bits are both positive integers.

6. The communication system according to claim 5, wherein the third index I3_t of the t^t track is obtained according to:

7. The communication system according to claim 6, wherein the second index I2_t of the t^th track is obtained according to:

8. The communication system according to claim 7, wherein the joint index Ind is obtained according to:

9. An audio signal encoding method for use by an audio signal encoder in a terminal device, the method comprising:

obtaining an audio signal;

determining number of pulses on each of T tracks of the audio signal, wherein T is an integer greater than or equal to 2;

collecting statistics of pulses on multiple positions on each track, wherein the statistics of pulses on a t^th track, 0≤

t≤

T−

1, include;

(a) number of positions N_t that have pulses, (b) distribution of the N_t positions on the t^th track, (c) number of pulses on each of the N_t positions, and (d) symbols of the pulses on each of the N_t positions;

determining, for each track, a first index I1_t according to the number of the positions N_t, and wherein all possible distributions of the N_t positions on the t^th track correspond to the first index I1_t, where 0≤

t≤

T−

1;

determining, for each track, a second index I2_t, wherein the second index I2_t indicates, among the all possible distributions corresponding to the first index I1_t, a current distribution of the N_t positions on the t^th track, where 0≤

t≤

T−

1;

determining, for each track, a third index I3_t by mapping distributions in which the N_t positions have pulses to distributions that the N_t positions have −

N_t pulses, where 0≤

t≤

T−

1, wherein (a) N_t represents a total number of pulses on the t^th track, (b) all possible distributions of the −

N_t pulses on the N_t positions are arrayed according to a set order, and (c) an arrayed serial number obtained by the above arraying process is used as the third index I3_t indicating the number of pulses on a position that has a pulse;

generating a symbol index Is_t according to the symbols of the pulses on each of the N_t positions;

generating, for each track, a joint index using information of the first, the second, the third, and the fourth indexes of the track;

comparing the joint index with an adjustment threshold (THR), wherein THR≤

2^Bmax−

I_max(T), I_max(T) represents an upper limit of the joint index, and Bmax represents an upper limit of the number of bits used for encoding the joint index; and

when the joint index is smaller than the THR, encoding the joint index by using a first number of code bits and transmitting the encoded joint index;

or

when the joint index is greater than or equal to the THR, encoding the joint index plus an offset value (THR₀) by using a second number of code bits and transmitting the encoded joint index plus the THR₀, wherein (a) THR≤

THR₀≤

2^Bmax−

I_max(T), (b) the first number of coding bits is smaller than the second number of coding bits, (c) the second number of coding bits is smaller than or equal to Bmax, and (d) the first number of coding bits and the second number of coding bits are both positive integers.

10. The method according to claim 9, wherein the third index I3_t of the t^th track is obtained according to:

11. The method according to claim 10, wherein the second index I2_t of the t^th track is obtained according to:

12. The terminal device according to claim 11, wherein the joint index Ind is obtained according to: