PULSE ENCODING AND DECODING METHOD AND PULSE CODEC

• US 20130124199A1
• Filed: 12/21/2012
• Published: 05/16/2013
• 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
• Granted Patent: US 9,020,814 B2
• Time in Patent Office: Days
• US Class Current: 704/205
• 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 pulse encoding method, comprising:

obtaining pulses that are on T tracks and required to be encoded, wherein T is an integer greater than or equal to 2;

separately collecting, according to positions, statistics about a pulse that is on each track and required to be encoded, to obtain the number N_t of positions that have pulses on each track, distribution of the positions that have pulses on the track, and the number of pulses on each position that has a pulse, wherein the subscript t represents a t^th track, and tε

[0, T−

1];

according to the number {N₀, N₁, . . . , N_T-1} of positions that have pulses and are on each track, determining a first index I1, wherein the first index I1 corresponds to all possible distribution situations of positions that have pulses and are on each track under the number of the positions having pulses, wherein the number of the positions having pulses is represented by it;

determining a second index I2_t of each track separately according to distribution of positions that have pulses and are on each track, wherein the second index indicates, among all possible distribution situations corresponding to the first index I1, a distribution situation which corresponds to distribution of current positions having pulses on a corresponding track;

determining a third index I3_t of each track separately according to the number of pulses on each position that has the pulse and is on each track; and

generating a code index Ind, wherein the code index comprises information of the first index and the second and third indexes of each track.

2. The method according to claim 1, wherein:

during the separately collecting, according to positions, statistics about a pulse that is on each track and required to be encoded, according to a positive or negative feature of a pulse symbol of each position that has the pulse and is on each track, pulse symbol information of each position that has the pulse and is on each track is obtained; and

the code index further comprises information of a symbol index which corresponds to each position that has the pulse and is on each track, and the symbol index indicates pulse symbol information which is of a position that has a pulse and corresponds to the index.

3. The method according to claim 1, wherein:

one first index corresponds to one {N₀, N₁, . . . , N_T-1} combination, or,

at least one first index corresponds to more than two {N₀, N₁, . . . , N_T-1} combinations;

for a track with a non-one N_t value corresponding to the first index, besides determining second and third indexes of the track, an additional index corresponding to the number of current positions that have pulses and are on the track is further determined, the additional index corresponds to all possible distribution situations of positions that have pulses and are on the track under the number of positions having pulses, wherein the number of positions having pulses is represented by it, and the code index further comprises information of the additional index.

4. The method according to claim 3, wherein the code index Ind is generated by adopting the following manner:

5. The method according to claim 1, wherein after the step of generating the code index, the method further comprises:

comparing the code index Ind with an adjustment threshold THR, wherein

THR≦

2^Bmax−

I_max(T),

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

if Ind is smaller than THR, code bits, the number of which is the first number, are adopted to encode Ind;

otherwise, code bits, the number of which is the second number, are adopted to encode Ind plus an offset value THR₀, wherein THR≦

THR₀≦

2^Bmax−

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

6. The method according to claim 5, wherein correspondence between the first index and a {N₀, N₁, . . . , N_T-1} combination is determined by adopting the following manner:

collecting statistics about a probability of occurrence of the {N₀, N₁, . . . , N_T-1} combination, to make a first index corresponding to a combination of a higher probability of occurrence be smaller.

7. The method according to claim 1, wherein the step of determining a third index I3_t of each track separately according to the number of pulses on each position that has the pulses and is on each track comprises:

for the t^th track, situations that N_t positions having pulses have N pulses are mapped to situations that N_t positions have N_t−

N₁ pulses, wherein N represents the total number of pulses required to be encoded on the t^th track; and

according to set order, all possible distribution situations of N_t−

N_t pulses on N_t positions are arrayed, and an arrayed serial number is used as the third index I3_t indicating the number of pulses on a position that has a pulse.

8. The method according to claim 7, wherein a calculation formula of the third index I3_t of each track is:

9. The method according to claim 1, wherein a calculation formula of the second index I2_t of each track is:

10. A pulse encoding method, comprising:

obtaining pulses that are on T tracks and required to be encoded, wherein T is an integer greater than or equal to 2;

separately collecting, according to positions, statistics about a pulse that is on each track and required to be encoded, to obtain the number N_t of positions that have pulses on each track, distribution of the positions that have pulses on the track, and the number of pulses on each position that has a pulse, wherein the subscript t represents a t^th track, and tε

[0, T−

1];

according to the number of positions that have pulses and are on each track, determining a first index I1_t of each track, wherein the first index I1_t corresponds to all possible distribution situations of positions that have pulses and are on the track under the number of the positions having pulses, wherein the number of the positions having pulses is represented it;

determining a second index I2_t of each track separately according to distribution of positions that have pulses and are on each track, wherein the second index indicates, among all possible distribution situations corresponding to the first index, a distribution situation which corresponds to distribution of current positions having pulses and is on the track;

determining a third index I3_t of each track separately according to the number of pulses on each position that has the pulse and is on each track; and

generating a code index Ind, wherein the code index comprises information of the first, second, and third indexes of each track.

11. A pulse decoding method, comprising:

obtaining a code index Ind, extracting a first index from the code index, and determining, according to the first index, the number {N₀, N₁, . . . , N_T-1} of positions that have pulses and are on each track of T tracks, wherein the subscript t of N_t represents a t^th track, tε

[0, T−

1], and T is an integer greater than or equal to 2;

extracting a second index I2_t of each track and a third index I3_t of each track from the code index;

for each track, according to the second index, determining distribution of positions that have pulses on the track under the number of positions having pulses, wherein the number of positions having pulses corresponds to the first index;

for each track, according to the third index, determining the number of pulses on each position that has pulse; and

for each track, according to distribution of the positions that have pulses on the track and the number of pulses on each position that has the pulse, reconstructing a pulse sequence on the track.

12. The method according to claim 11, wherein the extracting the first index from the code index adopts:

judging a value range to which the code index belongs among several set independent value ranges, and determining the first index according to a starting value corresponding to the value range to which the code index belongs.

13. The method according to claim 11, wherein:

one first index corresponds to one {N₀, N₁, . . . , N_T-1} combination, or,

at least one first index corresponds to more than two {N₀, N₁, . . . , N_T-1} combinations;

for a track with a non-one N_t value corresponding to the first index, besides extracting the second and third indexes of the track, an additional index corresponding to the number of current positions that have pulses and are on the track is further extracted, and the additional index corresponds to all possible distribution situations of positions that have pulses and on the track under the number of positions having pulses, wherein the number of positions having pulses is represented by it.

14. The method according to claim 11, wherein the step of obtaining the code index Ind comprises:

extracting code bits, the number of which is the first number, from an encoded code stream;

if a decoded value of the code bits, the number of which is the first number, is smaller than an adjustment threshold THR, using the decoded value of the code bits, the number of which is the first number, as a code index Ind;

otherwise, increasing the number of extracted code bits to the second number, and using a value obtained by subtracting an offset value THR₀ from a decoded value of code bits, the number of which is the second number, as a code index Ind.

15. A pulse decoding method, comprising:

obtaining a code index Ind, extracting a first index I1_t of each track from the code index, and for each track, determining the number N_t of positions having pulses according to the first index, wherein the subscript t represents a t^th track, tε

[0, T−

1], and T is an integer greater than or equal to 2;

extracting a second index I2_t of each track and a third index I3_t of each track from the code index;

for each track, according to the second index, determining distribution of positions that have pulses on the track under the number of positions having pulses, wherein the number of positions having pulses corresponds to the first index;

for each track, according to the third index, determining the number of pulses on each position that has a pulse; and

for each track, according to distribution of the positions that have pulses on the track and the number of pulses on each position that has the pulse, reconstructing a pulse sequence on the track.

16. A pulse encoder, comprising:

a pulse statistics unit, configured to obtain pulses that are on T tracks and required to be encoded, wherein T is an integer greater than or equal to 2; and

separately collect, according to positions, statistics about a pulse that is on each track and required to be encoded, to obtain the number N_t of positions that have pulses on each track, distribution of the positions that have pulses on the track, and the number of pulses on each position that has a pulse, wherein the subscript t represents a t^th track, and tε

[0, T−

1];

an index calculation unit, wherein the index calculation unit comprises;

a first index unit, configured to, according to the number {N₀, N₁, . . . , N_T-1} of positions that have pulses and are on each track, output a first index I1, wherein the first index corresponds to all possible distribution situations of positions that have pulses and are on each track under the number of the positions having pulses, wherein the number of the positions having pulses is represented by it;

a second index unit, configured to output a second index I2_t of each track separately according to distribution of positions that have pulses and are on each track, wherein the second index indicates, among all possible distribution situations corresponding to the first index, a distribution situation which corresponds to distribution of current positions having pulses on a corresponding track; and

a third index unit, configured to output a third index I3_t of each track separately according to the number of pulses on each position that has a pulse and is on the track; and

an index combination unit, configured to combine information of the first index I1 and the second and third indexes of each track to generate a code index Ind.

17. The encoder according to claim 16, wherein at least one first index corresponds to more than two {N₀, N₁, . . . , N_T-1} combinations,

the index calculation unit further comprises an additional index unit, configured to, for a track with a non-one N_t value corresponding to the first index, determine an additional index corresponding to the number of current positions that have pulses and are on the track, wherein the additional index corresponds to all possible distribution situations of positions that have pulses and are on the track under the number of positions having pulses, wherein the number of positions having pulses is represented by it;

and

the index combination unit further combines information of the additional index into the code index.

18. The encoder according to claim 16, further comprising a code bit adjustment unit, configured to compare the code index Ind with an adjustment threshold THR after the index combination unit generates the code index, wherein

THR≦

2^Bmax−

I_max(T),

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

if Ind is smaller than THR, code bits, the number of which is the first number, are adopted to encode Ind;

otherwise, code bits, the number of which is the second number, are adopted to encode Ind plus an offset value THR₀, wherein THR≦

THR₀≦

2^Bmax−

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

19. A pulse decoder, comprising:

a first extraction unit, configured to obtain a code index Ind, extract a first index from the code index, and determine, according to the first index, the number {N₀, N₁, . . . , N_T-1} of positions that have pulses and are on each track of T tracks, wherein the subscript t of N_t represents a t^th track, tε

[0, T−

1], and T is an integer greater than or equal to 2;

a second extraction unit, configured to extract a second index I2_t of each track and a third index I3_t of each track from the code index;

a first decoding unit, configured to, for each track, according to the second index, determine distribution of the positions that have pulses on the track under the number of positions having pulses, wherein the number of positions having pulses corresponds to the first index;

a second decoding unit, configured to, for each track, according to the third index, determine the number of pulses on each position that has a pulse; and

a pulse reconstruction unit, configured to, for each track, according to distribution of the positions that have pulses on the track and the number of pulses on each position that has the pulse, reconstruct a pulse sequence on the track.

20. The decoder according to claim 19, wherein at least one first index corresponds to more than two {N₀, N₁, . . . , N_T-1} combinations, and the decoder further comprises:

an additional extraction unit, configured to, for a track with a non-one N_t value corresponding to the first index, extract an additional index corresponding to the number of current positions that have pulses and are on the track, wherein the additional index corresponds to all possible distribution situations of positions that have pulses and are on the track under the number of positions having pulses, wherein the number of positions having pulses is represented by it; and

the second extraction unit extracts the second index I2_t of the track and the third index I3_t of the track according to the number of current positions that have pulses and are on a corresponding track, wherein the number of current positions that have pulses and are on a corresponding track is determined by the additional index extracted by the additional extraction unit.

21. The decoder according to claim 19, further comprising a decoding bit adjustment unit, configured to extract code bits, the number of which is the first number, from an encoded code stream;

if a decoded value of the code bits, the number of which is the first number, is smaller than an adjustment threshold THR, use the decoded value of the code bits, the number of which is the first number, as a code index Ind for output;

otherwise, increase the number of extracted code bits to the second number, and use a value obtained by subtracting an offset value THR₀ from a decoded value of code bits, the number of which is the second number, as a code index Ind for output.