Pulse encoding and decoding method and pulse codec

• US 9,858,938 B2
• Filed: 10/28/2016
• Issued: 01/02/2018
• 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.)
• Inventors: Ma, Fuwei, Zhang, Dejun
• Primary Examiner(s): BAKER, MATTHEW H
• Application Number:
  US15/338,098
• Publication Number:
  US 20170053657A1
• Time in Patent Office: 431 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. A terminal device with an audio coder comprising a processor and non-transitory computer readable medium storing instructions for execution by the processor such that when the instructions are executed by the processor, the processor is configured to perform:

determining pulses that are on T tracks of a speech signal and required to be encoded, wherein T is an integer greater than or equal to 2;

separately collecting, according to positions on the T tracks, statistics about pulses on each track and to be encoded, wherein the statistics include (a) a number N_t of positions that have pulses on each track, wherein the subscript t represents a t^th track, t∈

[0, T−

1], (b) distribution of the N_t positions, and (c) a number of pulses on each position that has a pulse;

determining a first index of each track according to the number of the N_t positions, wherein the first index corresponds to all possible distribution situations of the N_t positions;

determining a second index of each track according to a distribution of the N_t positions, wherein the second index indicates, among the all possible distribution situations corresponding to the first index, a distribution situation corresponding to a current distribution of the N_t positions;

determining a third index of each of the T tracks by mapping situations in which the N_t positions have _t pulses to situations that the N_t positions have _t−

N_t pulses for the t^th track, wherein (a) _t represents a total number of pulses to be encoded on the t^th track, (b) all possible distribution situations of the _t−

N_t pulses on the N_t positions are arrayed according to a set order, and an arrayed serial number is used as the third index indicating the number of pulses on a position that has a pulse;

generating a joint index comprising information of the first, second, and third indexes of each of the tracks;

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

THR≦

2^Bmax−

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

if the joint index is smaller than THR, the joint index is encoded by using a first number of code bits then transmitted;

otherwise, the joint index plus an offset value THR₀ is encoded by using a second number of code bits then transmitted, wherein (a) THR≦

THR₀≦

2^Bmax−

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

2. The terminal device according to claim 1, wherein the third index of each track is obtained through the following:

3. The terminal device according to claim 1, wherein the second index of each track is obtained through the following:

4. The terminal device according to claim 1, wherein the processor is further operated to perform:

when separately collecting the statistics about the pulse that is on each track of the speech signal and required to be encoded, obtaining pulse symbol information of each position that has the pulse and is on each track; and

wherein the statistics are collected according to a positive or negative feature of a pulse symbol of each position that has the pulse and is on each track;

wherein the joint index further comprises information of a symbol index which corresponds to the N_t positions on each track, and the symbol index indicates pulse symbol information of the N_t positions and corresponds to the joint index.

5. A communication system with an audio coder and an audio decoder, the audio coder comprising a processor and non-transitory computer readable medium storing instructions for execution by the processor such that when the instructions are executed by the processor, the processor is configured to perform:

determining pulses that are on T tracks of a speech signal and required to be encoded, wherein T is an integer greater than or equal to 2;

separately collecting, according to positions on the T tracks, statistics about a pulse on each track and to be encoded, wherein the statistics include (s) a number N_t of positions that have pulses on each track, wherein the subscript t represents a t^th track, t∈

[0, T—

1], (b) distribution of the N_t positions, and (c) a number of pulses on each position that has a pulse;

determining a first index of each track according to the number of the N_t positions wherein the first index corresponds to all possible distribution situations of the N_t positions;

determining a second index of each track according to distribution of the N_t positions, wherein the second index indicates, among all possible distribution situations corresponding to the first index, a distribution situation corresponding to a current position of the N_t positions;

determining a third index of each of the T tracks by mapping situations in which the N_t positions have _t pulses to situations that N_t positions have _t−

N_t pulses for the t^th track, wherein (a) _t represents a total number of pulses to be encoded on the t^th track, (b) all possible distribution situations of _t−

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

generating, a joint index, wherein the joint index comprises information of the first, second, and third indexes of each of the tracks;

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

THR≦

2^Bmax−

I_max(T),

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

if the joint index is smaller than THR, the joint index is encoded by using a first number of code bits then transmitted, wherein (a) THR≦

THR₀≦

2^Bmax−

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

6. The communication system according to claim 5, wherein the third index of each track is obtained through the following:

7. The communication system according to claim 5, wherein the second index of each track is obtained through the following:

8. The communication system according to claim 5, wherein the processor is further operated to perform:

when separately collecting, the statistics about the pulse that is on each track of the speech signal and required to be encoded, obtaining pulse symbol information of each position that has the pulse and is on each track; and

wherein the statistics are collected according to a positive or negative feature of a pulse symbol of each position that has the pulse and is on each track;

wherein the joint index further comprises information of a symbol index which corresponds to the N_t positions on each track, and the symbol index indicates pulse symbol information of the N_t positions and corresponds to the joint index.

9. An audio coding method implemented by an audio coder at a terminal device, the method comprising:

determining pulses that are on T tracks of a speech signal and required to be encoded, wherein T is an integer greater than or equal to 2;

separately collecting, according to positions, statistics about pulses on each track and to be encoded, wherein the statistics include (a) a number N_t of positions that have pulses on each track, wherein the subscript t represents a t^th track, and t∈

[0, T—

1], (b) distribution of the positions, and (c) a number of pulses on each position that has a pulse.

determining a first index of each track according to the number of the N_t position wherein the first index corresponds to all possible distribution situations of the N_t positions;

determining, a second index of each track according to distribution of the N_t positions, wherein the second index indicates, among all possible distribution situations corresponding to the first index, a distribution situation corresponding to a current position of the N_t positions;

determining a third index of each of the T tracks by mapping situations in which the N_t positions have _t pulses to situations that N_t positions have _t−

N_t pulses for the t^th track;

wherein (a) _t represents a total number of pulses to be encoded on the t^th track, (b) all possible distribution situations of _t−

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

generating, a joint index comprising information of the first, second, and third indexes of each of the tracks;

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

THR≦

2^Bmax−

I_max(T),

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

if the joint index is smaller than THR, the joint index is encoded by using a first number of code bits then transmitted;

otherwise, the joint index plus an offset value THR₀ is encoded by using a second number of code bits then transmitted, wherein (a) THR≦

THR₀≦

2^Bmax−

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

10. The method according to claim 9, wherein the third index of each track is obtained through the following:

11. The method according to claim 9, wherein the second index of each track is obtained through the following:

12. The method according to claim 9, wherein the separately collecting the statistics about the pulse that is on each track of the speech signal and required to be encoded, further comprises:

obtaining pulse symbol information of each position that has the pulse and is on each track;

wherein the statistics are collected according to a positive or negative feature of a pulse symbol of each position that has the pulse and is on each track; and

wherein the joint index further comprises information of a symbol index which corresponds to the N_t positions on each track, and the symbol index indicates pulse symbol information of the N_t positions and corresponds to the joint index.