CN101989428B - Bit distribution method, coding method, decoding method, coder and decoder - Google Patents
Bit distribution method, coding method, decoding method, coder and decoder Download PDFInfo
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Abstract
The invention provides a bit distribution method comprising the following steps: carrying out perceptual sorting on all subbands of a signal according to the energy of the subband; according to the magnitude of frequency ranges corresponding to the subbands on a frequency domain and the energy difference of the subbands, adjusting the sequence of the subbands in the perceptual sorting; and distributing the bit resource according to the adjusted perceptual sorting sequence. The invention also provides a coding method, a coder, a bit distribution method, a decoding method and a decoder. By using the invention, the complexity of bit distribution can be lowered, and bit can be more reasonably distributed to the subbands with important perception, thereby ensuring that the coder and the decoder can generate better hearing feeling.
Description
Technical field
The present invention relates to encoding and decoding technique, relate in particular to the Bit Allocation in Discrete technology.
Background technology
The sub-band coding technology is one of encoding and decoding technique commonly used at present.Sound signal can be divided into a plurality of frequency bands from low to high on frequency domain, a frequency band is called as a subband, and work such as follow-up coding, decoding are all carried out on the basis of subband.In encoding-decoding process, need limited bit resource is distributed at intersubband, generally; The bit that subband obtains is many more, and the error during quantification is just more little, and the encoding and decoding quality is just good more; Otherwise; If the bit that subband obtains is few more, the error when then quantizing is just big more, and the encoding and decoding quality is just poor more.
Bit Allocation in Discrete is a criterion with the apperceive characteristic of people's ear generally.The physiological property of people's ear has determined that people's ear is not that signal to all frequencies all has identical sensitivity.Be embodied in: one, people Er Gengyi discovers the appearance and the variation of low frequency signal, by contrast, is difficult for discovering the appearance and the variation of high-frequency signal; Two, when low frequency signal and high-frequency signal occur simultaneously, people's ear possibly can only be heard low frequency signal, and can't hear high-frequency signal; This phenomenon is called " masking effect "; Its generation is relevant with frequency, the energy of signal, when satisfying certain condition, promptly can take place.For this characteristic of people's ear, can go simulation through setting up psychoacoustic model.Another important auditory perception property of people's ear is; Under quiet environment; People's ear can only be heard the sound of amplitude greater than certain threshold value; And this threshold value promptly is the magnitude of sound that people's ear just can have been heard, this threshold value is called as the absolute threshold of audibility (LTQ, Listening Threshold in Quiet) of people's ear.The LTQ curve changes along with frequency, and it can reflect this apperceive characteristic to different frequency of people's ear well.When Bit Allocation in Discrete, can only consider amplitude greater than the LTQ part, this is because people's ear can't the sound of perception under LTQ.
It is that psychoacoustic model is applied in the assigning process that optimal bit is distributed, and makes that limited bit resource distributes to as much as possible that people Er Yi discovers, on the not masked subband, to reach the optimum of human auditory system impression.On the other hand, under the prerequisite that does not influence the human auditory system effect, reduce encoder bit rate as much as possible, realize high efficiency coding.
At present, there is multiple Bit Allocation in Discrete scheme can be used for Bit Allocation in Discrete.Two kinds of Bit Allocation in Discrete schemes wherein are following:
1. adopt sensor model to instruct the Bit Allocation in Discrete of subband.The essence of sensor model is masking threshold; The estimation of masking threshold is real-time, and process is following: according to the frequency point ranges that current input signal comprises, calculate the sound pressure level (SPL) of each frequency; Then; Calculate the transport function (spread function) of each frequency, estimate masking threshold afterwards, the masking threshold of each subband of masking threshold final decision of all frequencies.After obtaining sensor model, cover than (SMR) according to the letter of the masking threshold of the signal amplitude of each subband and subband and to carry out Bit Allocation in Discrete.
2. adopt embedded variable Rate codec; Its 4～12 layers are time domain aliasing elimination (TDAC) scrambler; Discrete cosine transform (MDCT, Modified Discrete Cosine Transform) coefficient with the correction in 0～7000Hz frequency band when TDAC encodes has been divided into 18 subbands, carries out the perceptual importance ordering according to the quantification energy size of each subband; It is big more to quantize energy; Perception is important more, carries out Bit Allocation in Discrete according to the ordering of perceptual importance then, utilizes the binary search of oppositely filling out the water principle to realize the optimal bit distribution.Wherein, the subband that perceptual importance is high can be transmitted at lower level by priority encoding, can be by preferential decoding in decoding end; The subband that perceptual importance is low can be coded in the higher level transmission, might not receive the higher level coded message in decoding end because of the influence of transmission channel, in this case, just can not decode to it.
Inventor of the present invention finds in realizing process of the present invention: in Bit Allocation in Discrete scheme 1; In order to reach the purpose of high efficient coding, need set up meticulous sensor model in real time, calculated amount is big; Subsequently; Also need carry out repeatedly loop iteration, to reach the purpose of bit optimum allocation, the computation complexity of whole process is very high; In Bit Allocation in Discrete scheme 2; Only weigh the perceptual importance of each subband according to sub belt energy; And reckon without the apperceive characteristic that people's ear is high to the low frequency signal susceptibility, the high-frequency signal susceptibility is low; Also reckon without low frequency signal and cover the masking effect of high-frequency signal, cause Bit Allocation in Discrete and apperceive characteristic not to match, influence the encoding and decoding quality.
Summary of the invention
The embodiment of the invention provides Bit distribution method, coding method, coding/decoding method, scrambler and demoder, in the complexity that reduces sensor model, guarantees that codec can produce subjective preferably auditory effect.
A kind of Bit distribution method comprises: all subbands of signal are carried out the perception ordering according to the height of the energy of subband; According to the difference of the energy of the corresponding height of frequency range on frequency domain of subband and subband, the order of adjustment subband in perception is sorted; The bit resource is distributed according to the order of adjusted perception ordering.
A kind of coding method comprises: all subbands of signal are carried out the perception ordering according to the height of the energy of subband; According to the difference of the energy of the corresponding height of frequency range on frequency domain of subband and subband, the order of adjustment subband in perception is sorted; The bit resource is distributed according to the order of adjusted perception ordering; According to the result of Bit Allocation in Discrete, signal is carried out quantization encoding.
A kind of scrambler comprises: sequencing unit is used for all subbands of signal are carried out the perception ordering according to the height of the energy of subband; Adjustment unit is used for the difference according to the energy of the corresponding height of frequency range on frequency domain of subband and subband, the order of adjustment subband in perception is sorted; The Bit Allocation in Discrete unit is used for the bit resource is distributed according to the order of adjusted perception ordering; The quantization encoding unit is used for said Bit Allocation in Discrete unit distributes the bit resource according to the order of adjusted perception ordering after, according to the result of Bit Allocation in Discrete, signal being carried out quantization encoding.
A kind of Bit distribution method comprises: decoding obtains the energy of each subband of signal from code stream; All subbands are carried out the perception ordering according to the height of the energy of subband; According to the difference of the energy of the corresponding height of frequency range on frequency domain of subband and subband, the order of adjustment subband in perception is sorted; The bit resource is distributed according to the order of adjusted perception ordering.
A kind of coding/decoding method comprises: decoding obtains the energy of each subband of signal from code stream; All subbands are carried out the perception ordering according to the height of the energy of subband; According to the difference of the energy of the corresponding height of frequency range on frequency domain of subband and subband, the order of adjustment subband in perception is sorted; The bit resource is distributed according to the order of adjusted perception ordering; According to the result of Bit Allocation in Discrete, decoding obtains signal from code stream.
A kind of demoder comprises: first decoding unit is used for obtaining from code stream decoding the energy of each subband of signal; Sequencing unit is used for all subbands are carried out the perception ordering according to the height of the energy of subband; Adjustment unit is used for the difference according to the energy of the corresponding height of frequency range on frequency domain of subband and subband, the order of adjustment subband in perception is sorted; The Bit Allocation in Discrete unit is used for the bit resource is distributed according to the order of adjusted perception ordering; Second decoding unit is used for said Bit Allocation in Discrete unit distributes the bit resource according to the order of adjusted perception ordering after, and according to the result of Bit Allocation in Discrete, decoding obtains signal from code stream.
In an embodiment of the present invention; After all subbands of signal are carried out the perception ordering according to the height of the energy of subband; Can be according to the difference of the energy of height and the subband of the corresponding frequency range of subband on frequency domain; The order of adjustment subband in the perception ordering, in this case, the perceptual importance antithetical phrase band that is actually according to subband sorts.Like this, when allocation bit, can be preferably the allocation of subbands bit of perceptual important according to the order of subband arrangement.
When the bit inadequate resource; The embodiment of the invention can guarantee that the subband of perceptual important can obtain bit and is quantized to be delivered to decoding end, and decoding end can recover the information of this type subband, and this type subband is bigger to the influence of auditory perception; Though the less important subband of other perception possibly can not get bit; Decoding end also possibly can not recovered the information of this type subband, but because this type subband is very little to the auditory perception influence, so also can not cause very big sense of hearing error.Therefore, just can guarantee the auditory effect of codec through the embodiment of the invention.
When the bit resource more for a long time; If be after all allocation of subbands are crossed bit, remaining bits to be arranged still, can be preferably the allocation of subbands bit of perceptual important so once more; Like this; The quantified precision of this type subband will increase and improve along with bit, and the information of this type subband that decoding end recovers will be more accurate, all the more near original signal.
Description of drawings
In order to be illustrated more clearly in the embodiment of the invention or technical scheme of the prior art; To do to introduce simply to the accompanying drawing of required use in embodiment or the description of the Prior Art below; Obviously, the accompanying drawing in describing below only is some embodiments of the present invention, for those of ordinary skills; Under the prerequisite of not paying creative work, can also obtain other embodiment according to these accompanying drawings.
Fig. 1 is the process flow diagram of a kind of Bit distribution method of the embodiment of the invention;
Fig. 2 is the process flow diagram of a kind of coding method of the embodiment of the invention;
Fig. 3 is the logical organization synoptic diagram of a kind of scrambler of the embodiment of the invention;
Fig. 4 is the process flow diagram of the another kind of Bit distribution method of the embodiment of the invention;
Fig. 5 is the process flow diagram of a kind of coding/decoding method of the embodiment of the invention;
Fig. 6 is the logical organization synoptic diagram of a kind of demoder of the embodiment of the invention.
Embodiment
To combine the accompanying drawing in the embodiment of the invention below, the technical scheme in the embodiment of the invention is carried out clear, intactly description, obviously, described embodiment only is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills are not making the every other embodiment that is obtained under the creative work prerequisite, all belong to the scope of the present invention's protection.
The embodiment of the invention can be described from the angle of encoder respectively.At first the embodiment of the invention is described from the angle of scrambler.
At first a kind of Bit distribution method to the embodiment of the invention describes.As shown in Figure 1, comprising:
S101: all subbands of signal are carried out the perception ordering according to the height of the energy of subband.In practical application; All subbands to signal both can sort according to the descending order of the energy of subband; That is, the subband that energy is big comes before the little subband of energy, also can sort according to the ascending order of the energy of subband; That is, that energy is little subband comes before the big subband of energy.
Energy can be with spectrum envelope or its value of deriving (the for example quantized value after quantized value, the process LTQ weighting) expression.
S102: according to the difference of the energy of the corresponding height of frequency range on frequency domain of subband and subband, the order of adjustment subband in perception is sorted.
According to the energy size to the preliminary ordering of subband after, can also be simultaneously according to difference this two factors adjustment subbands the order in perception sort of the corresponding frequency range of subband at the energy of the height on the frequency domain and subband.Need to prove that the frequency range here is meant a band frequency scope, for example, the frequency range of certain subband is 2kHz～6kHz.
So that preliminary ordering is an example to subband according to the descending order of energy; If the position of any one first subband in said perception ordering comes after the position of second subband in said perception ordering; Frequency range and the corresponding adjacent frequency bands of said first subband that said second subband is corresponding; And the frequency range that said first subband is corresponding is lower than the corresponding frequency range of said second subband on frequency domain; The energy of the energy of then more said first subband and said second subband; If the gap of the energy of the energy of said first subband and said second subband has reached the threshold value that is provided with in advance, then change said first subband and said second subband position in the perception ordering.For example, suppose that frequency range each subband from low to high is: subband 1, subband 2, subband 3, subband 4 ..., carry out the perception ordering according to the energy of subband after, the order of each subband in the perception ordering is: 4,3,7,6 ....Change the order of each subband in perception ordering if desired, then determining the position of subband 1 in the perception ordering earlier is 4, with the subband 1 adjacent position of subband 2 in the perception ordering be 3; Because the position of subband 1 in the perception ordering is after the position of subband 2; So, judge the energy difference distance of subband 1 and subband 2 again, if energy difference is apart from reaching the threshold value that is provided with in advance; Then change subband 1 and the position of subband 2 in the perception ordering; That is, the location change of subband 1 in the perception ordering is 3, and the location change of subband 2 in the perception ordering is 4; Afterwards, determine subband 2 in perception ordering after changing position before the position of subband 3, so do not change; Afterwards, determine the position of subband 3 in the perception ordering after the position of subband 4, compare the energy difference distance of subband 3 and subband 4 again; If energy difference, is not then changed subband 3 and the position of subband 4 in the perception ordering apart from not reaching the threshold value that is provided with in advance, by that analogy; Last adjusted order is: 3,4,7; 6 ....
Again so that preliminary ordering is an example to subband according to the ascending order of energy; If the position of any one first subband in said perception ordering comes before the position of second subband in said perception ordering; Frequency range and the corresponding adjacent frequency bands of said first subband that said second subband is corresponding; And the frequency range that said first subband is corresponding is higher than the corresponding frequency range of said second subband on frequency domain; The energy of the energy of then more said first subband and said second subband; If the gap of the energy of the energy of said first subband and said second subband has reached the threshold value that is provided with in advance, then change said first subband and said second subband position in the perception ordering.
Certainly; Here how just to illustrate difference according to the energy of height and the subband of the corresponding frequency range of subband on frequency domain; Adjustment perception ordering, in practical application, how those skilled in the art can design the difference according to the energy of height and the subband of the corresponding frequency range of subband on frequency domain fully according to actual needs; Adjustment perception ordering illustrates here no longer one by one.
The perception ordering is very important in a bit allocation procedures step, and it has determined to give the order of each allocation of subbands bit.Still so that preliminary ordering is an example to subband according to the descending order of energy; When the bit inadequate resource; The subband of ordering after leaning on may divide less than bit, divides the subband less than bit also just can not be quantized coding, and demoder will can not get not being quantized the information of the subband of coding; So the quality of this part subband has just been lost.If reasonably carry out the perception ordering, so important subband will preferentially be assigned with bit, thereby has guaranteed that important subband can be quantized coding, and therefore demoder can obtain the information of important subband.
S103: the bit resource is distributed according to the order of adjusted perception ordering.
When allocation bit, be the allocation of subbands bit according to the position of subband in the perception ordering.Concrete, if subband is tentatively sorted, be followed successively by the allocation of subbands bit according to from front to back order so according to the descending order of energy.Still with subband put in order " subband 1, subband 2, subband 3, subband 4, subband 5 ... " be example, at first give subband 1 allocation bit, give subband 2 allocation bit afterwards, by that analogy, according to sequencing to the allocation of subbands bit.Certainly, if subband is tentatively sorted, so according to being followed successively by the allocation of subbands bit from back to preceding order according to the ascending order of energy.Still with subband put in order " subband 1, subband 2, subband 3, subband 4; subband 5 ... " be example, at first for coming last allocation of subbands bit, then for coming the allocation of subbands bit of the 2nd of inverse; By that analogy, be subband 5 allocation bit, be subband 4 allocation bit; Being subband 3 allocation bit, being subband 2 allocation bit, is subband 1 allocation bit at last.
In practical application, carried out Bit Allocation in Discrete after, possibly have the bit residue; The remaining bits that promptly is not assigned with in addition; In this case, can give the remaining bit of allocation of subbands according to the order of adjusted perception ordering again, till all remaining bits all have been assigned with.For example, the bit set table of supposing the subband of certain signal is { 6,9; 12}; The meaning of this bit set table is when being certain allocation of subbands bit of sort signal, can only be 6 bits of this allocation of subbands, 9 bits or 12 bits; Certainly, the maximum number bits for the allocation of subbands of sort signal is exactly 12.Again so that preliminary ordering is an example to subband according to the descending order of energy, suppose in first time during Bit Allocation in Discrete, for the subband 2 of sort signal has distributed 9 bits; If the bit that is not assigned with in addition after the Bit Allocation in Discrete in the first time; And all subbands that come before the subband 2 have all passed through Bit Allocation in Discrete for the second time, when being subband 2 allocation bit, can be that subband 2 distributes 3 bits more so; The bit number that subband 2 is obtained reaches maximum number bits, i.e. 12 bits.Certainly, how to distribute remaining bits also can design according to actual needs, illustrate no longer one by one here by those skilled in the art.
Obviously, the executive agent of S101, S102 and S103 is a scrambler.
S101 in the method shown in Figure 1, S102 and S103 can be applied in the cataloged procedure, and to this, the embodiment of the invention provides a kind of coding method.As shown in Figure 2, comprising:
S201: all subbands of signal are carried out the perception ordering according to the height of the energy of subband;
S202: according to the difference of the energy of the corresponding height of frequency range on frequency domain of subband and subband, the order of adjustment subband in perception is sorted;
S203: the bit resource is distributed according to the order of adjusted perception ordering;
S204:, signal is carried out quantization encoding according to the result of Bit Allocation in Discrete.
The associated description of method shown in Figure 2 can be referring to the associated description of method shown in Figure 1; For example; The associated description of S201 can be referring to the associated description of S101; The associated description of S202 can be referring to the associated description of S102, and the associated description of S203 can repeat no more referring to the associated description of S103 here.
Corresponding to method shown in Figure 1 and method shown in Figure 2, the embodiment of the invention provides a kind of scrambler.Please again referring to Fig. 3, comprising: sequencing unit 301 is used for all subbands of signal are carried out the perception ordering according to the height of the energy of subband; Adjustment unit 302 is used for the difference according to the energy of the corresponding height of frequency range on frequency domain of subband and subband, the order of adjustment subband in perception is sorted; Bit Allocation in Discrete unit 303 is used for the bit resource is distributed according to the order of adjusted perception ordering; Quantization encoding unit 304 is used for Bit Allocation in Discrete unit 303 distributes the bit resource according to the order of adjusted perception ordering after, according to the result of Bit Allocation in Discrete, signal being carried out quantization encoding.
The associated description of scrambler shown in Figure 3 can be referring to the associated description of method shown in Figure 1; For example; The associated description of sequencing unit 301 can be referring to the associated description of S101; The associated description of adjustment unit 302 can be referring to the associated description of S102, and the associated description of Bit Allocation in Discrete unit 303 can repeat no more referring to the associated description of S103 here.
Here need to prove that on behalf of the quantized value of the energy of each subband, scrambler can like this, just enrolled in the code stream to the quantized value coding of the spectrum envelope of each subband when encoding.
Method shown in Figure 1, method shown in Figure 2 and scrambler shown in Figure 3 all are to describe from the angle of scrambler, mention above, and the embodiment of the invention can also be described from the angle of demoder.
At first describe from the angle of demoder a kind of Bit distribution method to the embodiment of the invention.As shown in Figure 4, comprising:
S401: decoding obtains the energy of each subband of signal from code stream.
Behind the quantized value coding of scrambler to the spectrum envelope of each subband, quantized value is enrolled in the code stream.Corresponding, the demoder quantized value of the spectrum envelope that obtains each subband of can from code stream, decoding, thus can obtain the energy of each subband.
S402: all subbands are carried out the perception ordering according to the height of the energy of subband.
Associated description can be referring to the associated description of the S101 in the method shown in Figure 1.
S403: according to the difference of the energy of the corresponding height of frequency range on frequency domain of subband and subband, the order of adjustment subband in perception is sorted.
Associated description can be referring to the associated description of the S102 in the method shown in Figure 1.
S404: the bit resource is distributed according to the order of adjusted perception ordering.
Associated description can be referring to the associated description of the S103 in the method shown in Figure 1.
S401 in the method shown in Figure 4, S402, S403 and S404 can be applied in the decode procedure, and to this, the embodiment of the invention also provides a kind of coding/decoding method.As shown in Figure 5, comprising:
S501: decoding obtains the energy of each subband of signal from code stream.
Associated description can be referring to the associated description of the S401 in the method shown in Figure 4.
S502: all subbands are carried out the perception ordering according to the height of the energy of subband.
Associated description can be referring to the associated description of the S101 in the method shown in Figure 1.
S503: according to the difference of the energy of the corresponding height of frequency range on frequency domain of subband and subband, the order of adjustment subband in perception is sorted.
Associated description can be referring to the associated description of the S102 in the method shown in Figure 1.
S504: the bit resource is distributed according to the order of adjusted perception ordering.
Associated description can be referring to the associated description of the S103 in the method shown in Figure 1.
S505: according to the result of Bit Allocation in Discrete, decoding obtains signal from code stream.
Corresponding to method shown in Figure 4 and method shown in Figure 5, the embodiment of the invention provides a kind of demoder.See also Fig. 6, comprising: first decoding unit 601 is used for obtaining from code stream decoding the energy of each subband of signal; Sequencing unit 602 is used for all subbands are carried out the perception ordering according to the height of the energy of subband; Adjustment unit 603 is used for the difference according to the energy of the corresponding height of frequency range on frequency domain of subband and subband, the order of adjustment subband in perception is sorted; Bit Allocation in Discrete unit 604 is used for the bit resource is distributed according to the order of adjusted perception ordering; Second decoding unit 605 is used for Bit Allocation in Discrete unit 604 distributes the bit resource according to the order of adjusted perception ordering after, and according to the result of Bit Allocation in Discrete, decoding obtains signal from code stream.
The associated description of demoder shown in Figure 6 can be referring to the associated description of method shown in Figure 1 and method shown in Figure 4; For example; The associated description of first decoding unit 601 can be referring to the associated description of the S401 in the method shown in Figure 4; The associated description of sequencing unit 602 can be referring to the associated description of the S101 in the method shown in Figure 1; The associated description of adjustment unit 603 can be referring to the associated description of S102, and the associated description of Bit Allocation in Discrete unit 604 can repeat no more referring to the associated description of S103 here.
For making those skilled in the art more clearly understand the embodiment of the invention, introduce a preferred embodiment below.
At coding side, the one group of M point MDCT coefficient Y={y (j) that obtains, j=0 ..., K} is divided into N subband band (i), i=0 ..., N-1.The number of corresponding MDCT coefficient is nb_coef (i) in each subband,
The spectrum envelope of each subband is log_rms (i), and the bit number that coding side can be used for the MDCT coefficient quantization is nb_bits_max.The method of Bit Allocation in Discrete is following:
Coding side:
(1) all subband spectrum envelopes at first are quantized coding, put into code stream.
(2) by spectrum envelope log_rms (i) order from big to small all subbands are sorted, ranking results is ord [i], ord [i]=0 ..., N-1, spectrum envelope are big more, and ord [i] is more little, and perception is important more.
(3) by the order from the low frequency to the high frequency, judge successively whether the perception order of each subband meets apperceive characteristic, deterministic process is following:
The perception order ord [i] of i subband of If is greater than the perception order ord [i+1] of i+1 subband
Poor＞Thre of the spectrum envelope log_rms (i) of i subband of And if the spectrum envelope log_rms (i) of i+1 subband
Exchange the perception order of i subband and i+1 subband
End
End
Need to prove: a) subband is by tactic from the low frequency to the high frequency, and therefore, i relative i+1 the subband of subband is low-frequency band, and i+1 relative i+2 the subband of subband is low-frequency band, and the like.B) Thre is the threshold value of energy difference, can adopt empirical value to confirm or optimized Algorithm is confirmed, Thre ∈ R, in the present embodiment, Thre=0.5.
(4) according to adjusted perception ordering, give each allocation of subbands bit successively.The bit number that each MDCT coefficient in the subband should be assigned to is in theory determined by the spectrum envelope of this subband that directly the bit number that each subband should be assigned in theory is:
bit_rms(i)＝log_rms(i)×nb_coef(i)
According to maximum number bits nb_bits_max, the optimal bit of each subband is assigned as:
(5) if also have the bit resources left, the process of then reallocating by the perceptual importance of subband is following:
If a) remaining bit resource quantity allocatedbits＜nb_bits_max and 0≤i＜N then repeat b～d step.
B) according to the order of perceptual importance, order from important to unessential is selected subband band (ord [i]).
C) known possible Bit Allocation in Discrete is gathered R={q_bit
0, q_bit
1... }, wherein, q_bit
0＜q_bit
1＜... the number of bits that possibly be assigned to for subband.If the bit resource that this subband has been assigned to is bat_bit (ord [i])=q_bit
kIf, be that this subband increases the bit that distributes, consider known possibly be assigned to bit set R, then this allocation of subbands to bit should be q_bit
K+1
D) if allocatedbits+q_bits
K+1-q_bits
k≤nb_bits_max, then bat_bit (ord [i])=q_bit
K+1, allocatedbits=allocatedbits+q_bits
K+1-q_bits
k, otherwise bat_bit (ord [i])=q_bit
k
(6) according to final bit allocation result bat_bit (i) the MDCT coefficient of each subband is carried out quantization encoding, enroll code stream.
Decoding end:
(1) decoding obtains spectrum envelope log_rms (i) from the code stream that receives.
(2) adopt with coding side (2)～(5) identical means and confirm the bit number bat_bit (i) that each allocation of subbands arrives and the importance ranking ord [i] of subband.
(3) the bit number bat_bit (i) that arrives according to each allocation of subbands and the importance ranking ord [i] of subband, decoding obtains the MDCT coefficient of each subband from the code stream that receives successively.
In sum; The perception ordering of subband is confirmed in the influence of the energy of the comprehensive subband of the embodiment of the invention, these two kinds of factors of frequency, has guaranteed that the subband of perceptual important preferentially obtains the bit resource; The responsive quantized subband error of human auditory system is reduced, improved a tin mass metering greatly.Simultaneously, avoided the complicated calculations of psychoacoustic model, effectively reduced computation complexity, it is little to delay time, and resource consumption is few.
One of ordinary skill in the art will appreciate that all or part of flow process that realizes in the foregoing description method; Be to instruct relevant hardware to accomplish through computer program; Described program can be stored in the computer read/write memory medium; This program can comprise the flow process like the embodiment of above-mentioned each side method when carrying out.Wherein, described storage medium can be magnetic disc, CD, read-only storage memory body (Read-OnlyMemory, ROM) or at random store memory body (Random Access Memory, RAM) etc.
The above only is a preferred implementation of the present invention; Should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the principle of the invention; Can also make some improvement and retouching, these improvement and retouching also should be regarded as protection scope of the present invention.
Claims (22)
1. a Bit distribution method is characterized in that, comprising:
All subbands of signal are carried out the perception ordering according to the height of the energy of subband;
According to the difference of the energy of the corresponding height of frequency range on frequency domain of subband and subband, the order of adjustment subband in perception is sorted;
The bit resource is distributed according to the order of adjusted perception ordering.
2. the method for claim 1 is characterized in that, all subbands of signal are carried out the perception ordering according to the height of the energy of subband be specially: all subbands to signal carry out the perception ordering according to the descending order of the energy of subband.
3. method as claimed in claim 2 is characterized in that, according to the difference of the energy of the corresponding height of frequency range on frequency domain of subband and subband, the order of adjustment subband in perception is sorted specifically comprises:
If the position of any one first subband in said perception ordering comes after the position of second subband in said perception ordering; Frequency range and the corresponding adjacent frequency bands of said first subband that said second subband is corresponding; And the frequency range that said first subband is corresponding is lower than the corresponding frequency range of said second subband on frequency domain; The energy of the energy of then more said first subband and said second subband; If the gap of the energy of the energy of said first subband and said second subband has reached the threshold value that is provided with in advance, then change said first subband and said second subband position in the perception ordering.
4. like claim 2 or 3 described methods, it is characterized in that, the bit resource is distributed according to the order of adjusted perception ordering comprise: according to from front to back order allocation bit resource successively in the perception ordering.
5. method as claimed in claim 4; It is characterized in that; The bit resource distributed also according to the order of adjusted perception ordering comprise: if all distributed bit for each subband but also have unappropriated remaining bits; Then, all be assigned with until all remaining bits again according to the said unappropriated remaining bits of order assignment of said adjusted perception ordering.
6. the method for claim 1 is characterized in that, all subbands of signal are carried out the perception ordering according to the height of the energy of subband be specially: all subbands to signal carry out the perception ordering according to the ascending order of the energy of subband.
7. method as claimed in claim 6 is characterized in that, according to the difference of the energy of the corresponding height of frequency range on frequency domain of subband and subband, the order of adjustment subband in perception is sorted specifically comprises:
If the position of any one first subband in said perception ordering comes before the position of second subband in said perception ordering; Frequency range and the corresponding adjacent frequency bands of said first subband that said second subband is corresponding; And the frequency range that said first subband is corresponding is higher than the corresponding frequency range of said second subband on frequency domain; The energy of the energy of then more said first subband and said second subband; If the gap of the energy of the energy of said first subband and said second subband has reached the threshold value that is provided with in advance, then change said first subband and said second subband position in the perception ordering.
8. like claim 6 or 7 described methods, it is characterized in that, the bit resource distributed according to the order of adjusted perception ordering comprise: according in the perception ordering from the back to preceding order allocation bit resource successively.
9. method as claimed in claim 8; It is characterized in that; The bit resource distributed also according to the order of adjusted perception ordering comprise: if all distributed bit for each subband but also have unappropriated remaining bits; Then, all be assigned with until all remaining bits again according to the said unappropriated remaining bits of order assignment of said adjusted perception ordering.
10. a coding method is characterized in that, comprising:
All subbands of signal are carried out the perception ordering according to the height of the energy of subband;
According to the difference of the energy of the corresponding height of frequency range on frequency domain of subband and subband, the order of adjustment subband in perception is sorted;
The bit resource is distributed according to the order of adjusted perception ordering;
According to the result of Bit Allocation in Discrete, signal is carried out quantization encoding.
11. a scrambler is characterized in that, comprising:
Sequencing unit is used for all subbands of signal are carried out the perception ordering according to the height of the energy of subband;
Adjustment unit is used for the difference according to the energy of the corresponding height of frequency range on frequency domain of subband and subband, the order of adjustment subband in perception is sorted;
The Bit Allocation in Discrete unit is used for the bit resource is distributed according to the order of adjusted perception ordering;
The quantization encoding unit is used for said Bit Allocation in Discrete unit distributes the bit resource according to the order of adjusted perception ordering after, according to the result of Bit Allocation in Discrete, signal being carried out quantization encoding.
12. a Bit distribution method is characterized in that, comprising:
Decoding obtains the energy of each subband of signal from code stream;
All subbands are carried out the perception ordering according to the height of the energy of subband;
According to the difference of the energy of the corresponding height of frequency range on frequency domain of subband and subband, the order of adjustment subband in perception is sorted;
The bit resource is distributed according to the order of adjusted perception ordering.
13. method as claimed in claim 12 is characterized in that, all subbands of signal are carried out the perception ordering according to the height of the energy of subband be specially: all subbands to signal carry out the perception ordering according to the descending order of the energy of subband.
14. method as claimed in claim 13 is characterized in that, according to the difference of the energy of the corresponding height of frequency range on frequency domain of subband and subband, the order of adjustment subband in perception is sorted specifically comprises:
If the position of any one first subband in said perception ordering comes after the position of second subband in said perception ordering; Frequency range and the corresponding adjacent frequency bands of said first subband that said second subband is corresponding; And the frequency range that said first subband is corresponding is lower than the corresponding frequency range of said second subband on frequency domain; The energy of the energy of then more said first subband and said second subband; If the gap of the energy of the energy of said first subband and said second subband has reached the threshold value that is provided with in advance, then change said first subband and said second subband position in the perception ordering.
15. like claim 13 or 14 described methods, it is characterized in that, the bit resource distributed according to the order of adjusted perception ordering comprise: according to from front to back order allocation bit resource successively in the perception ordering.
16. method as claimed in claim 15; It is characterized in that; The bit resource distributed according to the order of adjusted perception ordering comprise: if all distributed bit for each subband but also have unappropriated remaining bits; Then, all be assigned with until all remaining bits again according to the said unappropriated remaining bits of order assignment of said adjusted perception ordering.
17. method as claimed in claim 12 is characterized in that, all subbands of signal are carried out the perception ordering according to the height of the energy of subband be specially: all subbands to signal carry out the perception ordering according to the ascending order of the energy of subband.
18. method as claimed in claim 17 is characterized in that, according to the difference of the energy of the corresponding height of frequency range on frequency domain of subband and subband, the order of adjustment subband in perception is sorted specifically comprises:
If the position of any one first subband in said perception ordering comes before the position of second subband in said perception ordering; Frequency range and the corresponding adjacent frequency bands of said first subband that said second subband is corresponding; And the frequency range that said first subband is corresponding is higher than the corresponding frequency range of said second subband on frequency domain; The energy of the energy of then more said first subband and said second subband; If the gap of the energy of the energy of said first subband and said second subband has reached the threshold value that is provided with in advance, then change said first subband and said second subband position in the perception ordering.
19. like claim 17 or 18 described methods, it is characterized in that, the bit resource distributed according to the order of adjusted perception ordering comprise: according in the perception ordering from the back to preceding order allocation bit resource successively.
20. method as claimed in claim 19; It is characterized in that; The bit resource distributed also according to the order of adjusted perception ordering comprise: if all distributed bit for each subband but also have unappropriated remaining bits; Then, all be assigned with until all remaining bits again according to the said unappropriated remaining bits of order assignment of said adjusted perception ordering.
21. a coding/decoding method is characterized in that, comprising:
Decoding obtains the energy of each subband of signal from code stream;
All subbands are carried out the perception ordering according to the height of the energy of subband;
According to the difference of the energy of the corresponding height of frequency range on frequency domain of subband and subband, the order of adjustment subband in perception is sorted;
The bit resource is distributed according to the order of adjusted perception ordering;
According to the result of Bit Allocation in Discrete, decoding obtains signal from code stream.
22. a demoder is characterized in that, comprising:
First decoding unit is used for obtaining from code stream decoding the energy of each subband of signal;
Sequencing unit is used for all subbands are carried out the perception ordering according to the height of the energy of subband;
Adjustment unit is used for the difference according to the energy of the corresponding height of frequency range on frequency domain of subband and subband, the order of adjustment subband in perception is sorted;
The Bit Allocation in Discrete unit is used for the bit resource is distributed according to the order of adjusted perception ordering;
Second decoding unit is used for said Bit Allocation in Discrete unit distributes the bit resource according to the order of adjusted perception ordering after, and according to the result of Bit Allocation in Discrete, decoding obtains signal from code stream.
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