CN1276406C - Method and apparatus for encoding/decoding audio data with scalability - Google Patents
Method and apparatus for encoding/decoding audio data with scalability Download PDFInfo
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- CN1276406C CN1276406C CNB031650368A CN03165036A CN1276406C CN 1276406 C CN1276406 C CN 1276406C CN B031650368 A CNB031650368 A CN B031650368A CN 03165036 A CN03165036 A CN 03165036A CN 1276406 C CN1276406 C CN 1276406C
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10L—SPEECH ANALYSIS OR SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING; SPEECH OR AUDIO CODING OR DECODING
- G10L19/00—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
- G10L19/04—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 using predictive techniques
- G10L19/16—Vocoder architecture
- G10L19/18—Vocoders using multiple modes
- G10L19/24—Variable rate codecs, e.g. for generating different qualities using a scalable representation such as hierarchical encoding or layered encoding
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B14/00—Transmission systems not characterised by the medium used for transmission
- H04B14/02—Transmission systems not characterised by the medium used for transmission characterised by the use of pulse modulation
- H04B14/04—Transmission systems not characterised by the medium used for transmission characterised by the use of pulse modulation using pulse code modulation
Abstract
An audio data encoding and decoding system and method are provided to adjust a bit rate lower than a complexity while they are offering an FGS(Fine Grain Scalability). The method comprises several steps. Additional data, including scale factor data and coding model data corresponding to the first layer, is encoded. Plural quantized samples are encoded by the unit of a symbol according to a sequence from a symbol with an MSB(Most Significant Bit) to a symbol with an LSB(Least Significant Bit). The number added at a layer is increased by one and the steps are repeated until the encoding process for all the layers are finished.
Description
Technical field
The present invention relates to the Code And Decode voice data, especially specifically, relate to and be used for coding audio data, so that the audio bitstream of coding has the method and apparatus of telescopic bit rate, and the method and apparatus that is used for decoding audio data.
Background technology
Because the development of Digital Signal Processing recently, in most cases sound signal is stored as digital signal and reproduction usually.DAB storing/restoring device is transformed into pulse code modulation (pcm) to sound signal by sampling and quantification, just digital signal.By such operation, DAB storage/reproduction device is at information storage medium, and such as storage pcm audio data in CD (CD) and the Digital video disc (DVD), and response user's order is reproduced the signal of storage so that the user can listen voice data.With respect to the analogy method of using fine groove (LP) record or tape, stored digital/restoration methods has improved audio quality widely, and has significantly reduced the deterioration that is caused by the long memory cycle.Yet because a large amount of numerical datas, numerical approach is existing problems aspect storage and transmission.
For addressing this problem, various compression methods are used to the compression digital audio frequency signal.
In motion picture expert group (MPEG), perhaps among the AC-2/AC-3 by the Dolby exploitation, use psychoacoustic model to reduce data volume by ISO standardsization.As a result of, data volume can be reduced effectively and no matter the characteristic of signal how.In other words, MPEG/ audio standard or AC-2/AV-3 method can provide almost identical with CD audio quality with the bit rate of 64～384Kbps only, this bit rate be previous digital coding method bit rate 1/6 to 1/8.
Yet in these methods, search is applicable to the optimum condition of fixed bit rate and then carries out and quantizes and coding.Therefore, if when sending bit stream by network because the very poor transmission bandwidth that makes of network condition is lowered, may occur disconnecting with suitable service and can not offer the user again.In addition, the bit stream that is transformed into reduced size when bit stream expectation should be carried out encoding process reducing the size of bit stream again, and increase required calculated amount when more being applicable to the mobile device with limited memory capacity.
For addressing this problem, applicant of the present invention has proposed korean patent application No.97-61298, on November 19th, 1997, title " uses the method and apparatus of the scalable bit rate audio coding/decoding of position section algorithm coding (BSAC) ", this patent is authorized to Korean patent No. No.261253 on April 17th, 2000.According to the BSAC technology, have the high bit rate bitstream encoded and can be become bit stream, and can only recover with bit stream partly with low bit rate.Therefore, when network over loading, perhaps during the poor performance of demoder, or the user by only using the bit stream of part, can offer the user to the service with certain audio quality when asking low bit rate, although along with the decline of bit rate, quality can descend inevitably pro rata.
Yet because the BSAC technology adopts arithmetic coding, complicacy is very high, and when being implemented in the device of BSAC technology in reality, cost increases.In addition, because the conversion of sound signal is carried out in BSAC technology utilization correction discrete cosine transform (MDCT), the audio quality in the low layer can be by serious damage.
Summary of the invention
Invention provides a kind of method and apparatus that is used for telescopically (with scalability) audio data encoding and decoding, is that fine granular scalability (RGS) provides lower complexity by this method and apparatus.
The present invention also is provided for a kind of method and apparatus of telescopically audio data encoding and decoding, by this method and apparatus, even when FGS is provided, also can provide audio quality preferably at low layer.
According to an aspect of the present invention, the method that is used for the telescopically coding audio data is provided, comprise coding corresponding to ground floor, comprise the additional information of scaling factor information and encoding model information, by reference encoding model information, with from utilizing symbol that highest significant position (MSB) forms mode up to the symbol that utilizes least significant bit (LSB) (LSB) to form, be a plurality of quantized samples of unit encoding in order with the symbol corresponding to ground floor, and along with each ordinal number that successively increases layer, repeated execution of steps is up to finishing a plurality of layers predetermined coding.
According to another aspect of the present invention, a kind of coding method is provided, comprise that section (slicing) audio frequency magnetic makes the section voice data corresponding to a plurality of layers according to this, acquisition is corresponding to a plurality of layers each calibration segment information and coding section information, based on the additional information that comprises scaling factor information and encoding model information corresponding to the calibration segment information of ground floor and coding section information coding, by the voice data of reference scaling factor information quantization corresponding to ground floor, obtain quantized samples, by reference encoding model information, with from utilizing symbol that highest significant position (MSB) forms mode up to the symbol that utilizes least significant bit (LSB) (LSB) to form, be the resulting a plurality of quantized samples of unit encoding in order with the symbol, and along with each ordinal number that successively increases layer, repeated execution of steps is up to finishing a plurality of layers predetermined coding.
This method may further include, before the coding additional information, obtain the bit range that allowed in each of a plurality of layers, wherein in the coding of a plurality of quantized samples that obtain, the number of coded-bit is counted, if the bit range of outnumbering corresponding to bit with the bit of counting, coding stops, even and after quantized samples is encoded entirely, if the number of the bit of counting is less than the bit range corresponding to bit, still uncoded bit is encoded into the scope that bit range allows after the low layer coding is done.
In addition, the section of voice data comprises the wavelet transform of carrying out voice data, and by the data with reference to cutoff frequency section wavelet transform, makes the data of cutting into slices corresponding to a plurality of layers.
The coding of voice data can comprise differential coding scaling factor information and encoding model information.
The coding of a plurality of quantized samples can comprise Huffman encoding (Huffman coding), and the coding of a plurality of quantized samples can be included in a plurality of quantized samples of mapping on the bit-planes, and according to from utilizing symbol that highest significant position (MSB) forms order, be the unit encoding sample with the symbol in the bit range that in a layer, allows corresponding to sample up to the symbol that utilizes least significant bit (LSB) (LSB) to form.
In the mapping of a plurality of quantized samples, K quantized samples is mapped on the bit-planes, and in the coding of sample, acquisition is corresponding to the scalar value of the symbol that is formed by K bit-binary data, and pass through with reference to K bit-binary data, the scalar value that obtains and carry out Huffman encoding corresponding to the scalar value that is higher than a symbol of current symbol on the bit-planes, wherein K is an integer.
According to another aspect of the present invention, a kind of method is provided, be used for the voice data that the telescopically decoding is encoded at hierarchy, comprise that decoding comprises corresponding to the scaling factor information of ground floor and the additional information of encoding model information, according to order from the symbol that forms by highest significant position (MSB) to the symbol that forms by least significant bit (LSB) (LSB), with the symbol is the unit decoding audio data, and pass through with reference to encoding model information acquisition quantized samples, the quantized samples that is obtained by reference scaling factor information inverse quantization, this inverse quantization sample of reciprocal transformation, and along with each ordinal number that successively increases layer, repeated execution of steps is up to finishing a plurality of layers predetermined decoding.
The decoding of additional information comprises differential decoding scaling factor and encoding model information.
In decoding audio data, obtain quantized samples by Huffman decoding.In addition, the decoding of voice data may further include according to from the symbol that formed by highest significant position (MSB) order up to the symbol that is formed by least significant bit (LSB) (LSB), in corresponding to the layer of voice data, be the unit decoding audio data with the symbol in the bit range that allowed, and arranged the bit-planes of the symbol of decoding to obtain quantized samples from it.
When decoding audio data, the 4*K bit-planes that acquisition is formed by decoding symbols, and when obtaining quantized samples, obtain K quantized samples from the 4*K bit-planes, wherein K is an integer.
According to another aspect of the present invention, a kind of device is provided, be used for the voice data that the telescopically decoding is encoded at hierarchy, comprise the deblocking unit, its decoding comprises corresponding to the scaling factor information of ground floor and the additional information of encoding model information, and by with reference to encoding model information, according to being the sample of unit decoding audio data and acquisition quantification with the symbol up to the order of the symbol that forms by least significant bit (LSB) (LSB) from the symbol that forms by highest significant position (MSB); The inverse quantization unit, its quantized samples by being obtained with reference to scaling factor information inverse quantization; With the reciprocal transformation unit, this inverse quantization sample of its reciprocal transformation.
Deblocking unit differential decoding scaling factor information and encoding model information, and by Huffman decoding output quantized samples.The deblocking unit is according to from the symbol that formed by highest significant position (MSB) order up to the symbol that is formed by least significant bit (LSB) (LSB), in corresponding to the layer of voice data, be the unit decoding audio data with the symbol in the bit range that allowed, and arranged the bit-planes of the symbol of decoding to obtain quantized samples from it.The 4*K bit-planes that the acquisition of deblocking unit is formed by the symbol of decoding, and, then obtain K quantized samples from the 4*K bit-planes, wherein K is an integer.
According to another aspect of the present invention, provide a kind of device, be used for the telescopically coding audio data, comprised the converter unit of converting audio frequency data; Quantifying unit, it passes through with reference to the converting audio frequency data of scaling factor information quantization corresponding to every layer, and the output quantized samples; And encapsulation unit, its coding comprises corresponding to every layer the scaling factor information and the additional information of encoding model information, and pass through with reference to encoding model information, according to from the symbol that forms by highest significant position (MSB) order, be a plurality of quantized samples of unit encoding from quantifying unit with the symbol up to the symbol that forms by least significant bit (LSB) (LSB).
Encapsulation unit obtains each calibration segment information and the coding section information corresponding to a plurality of layers, and based on the additional information that comprises scaling factor information and encoding model information corresponding to every layer calibration segment information and coding section information coding.
In addition, the number of the bit of encapsulation unit counting coding, if the bit number of counting surpasses the bit range corresponding to bit, coding stops, even and after quantized samples is encoded entirely, if the bit number of counting is less than the bit range corresponding to bit, still uncoded bits of encoded was to the scope of bit range permission after low layer coding finished.
Converter unit is carried out wavelet transform to voice data.
Encapsulation unit makes the data of cutting into slices corresponding to a plurality of layers by with reference to cutoff frequency section wavelet transform data.
Encapsulation unit differential coding scaling factor information and encoding model information.
Encapsulation unit Huffman encoding quantized samples.Particularly, encapsulation unit shines upon a plurality of quantized samples on bit-planes, and according to from the symbol that forms by highest significant position (MSB) order, be the unit decoding symbols with the symbol in the bit range that in layer, is allowed corresponding to symbol up to the symbol that forms by least significant bit (LSB) (LSB).
Encapsulation unit shines upon K quantized samples on bit-planes, acquisition is corresponding to the scalar value of the symbol that is formed by K bit-binary data, and pass through with reference to K bit-binary data, the scalar value that obtains, with carry out Huffman encoding corresponding to the scalar value that is higher than a symbol of current symbol on the bit-planes, wherein K is an integer.
Description of drawings
Preferred embodiments of the present invention will be described in detail with reference to the annexed drawings by combination, and it is clearer that above-mentioned purpose of the present invention and advantage will become, wherein:
Fig. 1 is the block scheme of code device according to a preferred embodiment of the present invention;
Fig. 2 is the block scheme of decoding device according to a preferred embodiment of the invention;
Fig. 3 is the structural drawing of frame, and described frame is formed on bitstream encoded in the hierarchy so that can the control bit rate;
Fig. 4 is the details drawing of the structure of additional information;
Fig. 5 is a reference diagram, in order to explain according to a kind of coding method of the present invention;
Fig. 6 is a reference diagram, in order to more specifically to explain according to coding method of the present invention;
Fig. 7 is a process flow diagram, is used to explain the coding method according to the preferred embodiment of the present invention;
Fig. 8 is a process flow diagram, is used to explain the coding/decoding method according to the preferred embodiments of the present invention; And
Fig. 9 is a process flow diagram, is used to explain the coding/decoding method according to another preferred embodiment of the present invention.
Embodiment
With reference to figure 1, according to the present invention, code device so that can control the bit rate of bitstream encoded, and comprises converter unit 11, tonequality unit 12, quantifying unit 13 and bit-envelope unit 14 with the hierarchy coding audio data.
Quantifying unit 13 according to corresponding to the scaling factor information of sound signal in each frequency range scalar quantization sound signal, make the shielding thresholding that the level of quantizing noise is provided less than tonequality unit 12 in the frequency range, so that the people can not perceive noise.Then, the sample of quantifying unit 13 output quantifications.In other words, by the noise as noise ratio-shielding ratio (NMR) that shielding thresholding and each frequency range of using calculating in the tonequality unit 12 produces, quantifying unit 13 is carried out and is quantized, and makes that the NMR value in the full frequency band is 0dB or littler.0dB or littler NMR value mean that the people can not the perception quantizing noise.
Bit-envelope unit 14 codings belong to every layer quantized samples and additional information, and with hierarchy encapsulation coded signal.Calibration segment information during additional information comprises every layer, coding section information, their scaling factor information and encoding model information.Calibration segment information and coding section information can be packaged into header message, and then are sent to decoding device.Otherwise calibration segment information and coding section information can be encoded and be packaged into every layer additional information, and then send to decoding device.Calibration segment information and coding section information can not be sent to decoding device, because they are pre-stored in the decoding device in some cases.
More particularly, when coding comprises additional information corresponding to the scaling factor information of ground floor and encoding model information, bit-envelope unit 14 is with reference to the encoding model information corresponding to ground floor, according to from the symbol that forms by highest significant position (MSB) order, be the coding that unit carries out sample and information with the symbol up to the symbol that forms by least significant bit (LSB) (LSB).Then, in the second layer, identical processing is repeated to carry out.In other words, carry out coding along with the increase of the number of plies, be done up to the coding of a plurality of predetermined layer.In the present embodiment, bit-envelope unit 14 differential coding scaling factor information and encoding model information, and Huffman encoding quantized samples.The hierarchy of the bitstream encoded according to the present invention will be explained in the back.
The calibration segment information is meant the information that is used for more suitably carrying out according to the frequency characteristic of sound signal quantification.When frequency field was divided into a plurality of frequency ranges and a suitable scaling factor and is assigned to each frequency range, the indication of calibration segment information was corresponding to every layer calibration section.Like this, every layer belongs at least one calibration section.Each calibration section has the scaling factor of a distribution.In addition, coding section information is meant that the frequency characteristic that is used for according to sound signal more suitably carries out information encoded.When frequency field was divided into a plurality of frequency ranges and suitable encoding model and is assigned to each frequency range, the indication of coding section information was corresponding to every layer coding section.Calibration section and coding section are main the division with the experience, and corresponding with it respectively scaling factor is determined based on identical mode with encoding model.
Fig. 2 is the block scheme according to the decoding device of the preferred embodiments of the present invention.
With reference to figure 2, the decoding device decoded bits flows to by network condition, and the performance of decoding device and the determined destination layer of user's selection make that the bit rate of bit stream can Be Controlled.Decoding device comprises deblocking unit 21, inverse quantization unit 22 and reciprocal transformation unit 23.
Simultaneously, from the header message of bit stream, or, obtain calibration segment information and coding section information by the additional information of decoding in every layer.Interchangeable, decoding device can shift to an earlier date store calibration segment information and coding section information.According to scaling factor information corresponding to sample, inverse quantization unit 22 inverse quantization and recover every layer in quantized samples.The sample that reciprocal transformation unit 23 frequencies/time map is recovered so that sample is transformed into the pcm audio data of time domain, and is exported it.
Fig. 3 is the structural drawing of frame, and described frame forms with the hierarchy bitstream encoded, and making can the control bit rate.
With reference to figure 3, be encoded into hierarchy according to the frame of bit stream of the present invention by mapping quantized samples and additional information, to obtain fine granular scalability (FGS).In other words, the low layer bit stream is included in the enhancement layer bit-stream of hierarchy.The additional information that needs in every layer is assigned to every layer and also then is encoded.
The stem zone that is used to store header message is placed in the front of bit stream, and the information of relevant layer 0 is packed the stem zone after then, then, belongs to packed in order as the information of layer 1-N of enhancement layer.Layer from the stem zone to layer 0 information is known as basic unit, and the layer from the stem zone to layer 1 information is known as layer 1 and the layer from the stem zone to layer 2 information is known as layer 2.Equally, the superiors represent from stem zone to a layer N information, in other words, from basic unit to layer N as enhancement layer.Additional information and coding audio data are stored as each layer information.For example, additional information 2 and coded quantization sample are stored stratification 2 information.Here, N is an integer more than or equal to 1.
Fig. 4 is the details drawing of the structure of additional information.
With reference to figure 4, additional information and coded quantization sample are stored as additional information arbitrarily, and in the present embodiment, additional information comprises the Huffman encoding model information, quantizing factor information, additional information and other additional information of relevant channel.The Huffman encoding model information is the index information of Huffman encoding model, should be used to encodes or decodes belong to corresponding to this information the layer quantized samples.Quantizing factor information indication quantization step, this step-length are used to quantize or inverse quantization belongs to voice data corresponding to the layer of information.The additional information of relevant channel be relevant channel such as the stereosonic information of M/S.Other additional information is the relevant stereosonic flag information of M/S that whether uses.
In the present embodiment, 14 pairs of Huffman encoding model informations in bit-envelope unit and quantizing factor information and executing differential coding.In differential coding, the direct difference value of the value of frequency range formerly is encoded.The additional information of relevant channel is by Huffman encoding.
Fig. 5 is a reference diagram, is used for more specifically explaining according to coding method of the present invention.
With reference to figure 5, the quantized samples that encode has 3-layer structure.The oblique line rectangle represents to comprise the spectrum line of quantized samples, and solid line is represented calibration section, dotted line presentation code section.Calibration section (1), (2), (3), (4) and (5) and coding section (1), (2), (3), (4) and (5) belong to layer 0.Calibration section (5) and (6) and coding section (6), (7), (8), (9) and (10) belong to layer 1.Calibration section (6) and (7) and coding section (11), (12), (13), (14) and (15) belong to layer 2.Simultaneously, definition layer 0 makes and carries out coding up to frequency range (a), and definition layer 1 makes and carries out coding up to frequency range (b), and definition layer 2, makes and carries out coding up to frequency range (c).
At first, use the corresponding encoded model in 100 bit range, to encode and belong to the quantized samples of layer 0.In addition,, belong to the calibration section (1) of layer 0 as the additional information of layer 0, (2), (3), (4) and (5) and coding section (1), (2), and (3), (4) and (5) are encoded.When being the unit encoding quantized samples with the symbol, the number of bit is counted.If the bit number of counting surpasses the bit range that allows, the coding of layer 0 is stopped, and layer 1 is by arithmetic coding.In the quantized samples that belongs to layer 0, when the permission bit number in layer 0 and 1 still had living space, uncoded quantized samples was encoded next time.
Next, the quantized samples that belongs to layer 1 is encoded, and wherein uses the coding section that belongs to layer 1, in other words, and coding section (6), (7), (8), the encoding model of a coding section under the quantized samples that will encode in (9) and (10).In addition,, belong to calibration section (5) and (6) and the coding section (6) of layer 1 as the additional information of layer 1, (7), (8), (9) and (10) are encoded.Even after coding all samples corresponding to layer 1, if in the bit range that allows, promptly still have living space in 100 bits, remaining not coded-bit is encoded in the layer 0, and up to allowing bit, promptly 100 bits are counted.Allow bit range if the bit number of counting at coding surpasses, the coding of layer 1 is stopped, and the coding of layer 2 begins.
At last, belong to layer 2 quantized samples and be encoded, wherein use the coding section that belongs to layer 2, be i.e. coding section (11), (12), (13), the encoding model of the coding section that the quantized samples that will encode in (14) and (15) is affiliated.In addition,, belong to calibration section (6) and (7) and the coding section (11) of layer 2 as the additional information of layer 2, (12), (13), (14) and (15) are encoded.Even after coding all samples corresponding to layer 2, if in the bit range that allows, promptly still have living space in 100 bits, remaining not coded-bit is encoded in the layer 0, and up to the bit that allows, promptly 100 bits are counted.
, all quantized samples do not consider the permission bit range of layer 0 if being encoded, if promptly all quantized samples are encoded, even surpass to allow bit range in number of coded bits, promptly (this means down one deck after 100, promptly some bits in the permission bit range of layer 1 are used to encode and work as anterior layer), common situation is that the quantized samples that belongs to layer 1 can not be encoded.Therefore, under the situation of scalable decoding, if to the layer of layer 1, carry out decoding in scope, owing to be not encoded corresponding to the scope of layer 1 all quantized samples to predetermined band (b), the quantized samples of decoding on the frequency that is lower than (b) can fluctuate, cause " Birdy " effect, wherein audio quality can worsen.
In determining a plurality of layers when (destination layer), the allocation bit scope is wherein considered the whole size of all voice datas that are encoded.Like this, do not have possibility and do not carry out coding because of the defective of the bit range of the bit of wherein arranging to be encoded.
When carrying out decoding in the mode opposite, according to the bit range count bits number that allows with encoding process.Therefore, the decoding of predetermined layer is regularly put and can be identified.
Fig. 6 is a reference diagram, in order to more specifically to explain according to coding method of the present invention.
According to the present invention, bit-envelope unit 14 is being carried out coding by bit plain code (bit-plain) coding and Huffman encoding to the quantized samples corresponding to each layer.A plurality of quantized samples are mapped on the bit-planes, so that then represent with binary mode, and in the bit range of every layer permission, according to being encoded up to the order of the symbol that forms by LSB from the symbol that forms by MSB.Information important on the bit-planes at first is encoded, and not too important information is encoded subsequently relatively.By such operation, be fixed in encoding process corresponding to every layer bit rate and frequency range, make it possible to reduce the distortion that is known as " Birdy effect ".
Fig. 6 example coding example in the case, be 4 or still less comprising the bit number of the symbol of MSB.When quantification sample 9,2,4 and 0 was mapped on the bit-planes, they were expressed with binary mode, just, are respectively 1001b, 0010b, 0100b and 0000b.In other words, in the present embodiment, be 4*4 as the size of the encoding block of the coding unit on the bit-planes.
The symbol msb that is formed by MSB is " 1001b ", and the symbol msb-1 that is formed by next MSB is " 0010b ", and the symbol msb-2 that is formed by next MSB is " 0100b ", and the symbol msb-3 that is formed by LSB is " 1000b ".
Be used for the Huffman model information of Huffman encoding, promptly code book index is shown in table 1:
Table 1
| Additional information | Validity (significance) | The Huffman model |
| ?0 | 0 | ?0 |
| ?1 | 1 | ?1 |
| ?2 | 1 | ?2 |
| ?3 | 2 | ?3 |
| ?4 | ||
| ?4 | 2 | ?5 |
| ?6 | ||
| ?5 | 3 | ?7 |
| ?8 | ||
| ?9 | ||
| ?6 | 3 | ?10 |
| ?11 | ||
| ?12 | ||
| ?7 | 4 | ?13 |
| ?14 | ||
| ?15 | ||
| ?16 | ||
| ?8 | 4 | ?17 |
| ?18 | ||
| ?19 | ||
| ?20 | ||
| ?9 | 5 | ?* |
| ?10 | 6 | ?* |
| 11 | ?7 | * |
| 12 | ?8 | * |
| 13 | ?9 | * |
| 14 | ?10 | * |
| 15 | ?11 | * |
| 16 | ?12 | * |
| 17 | ?13 | * |
| 18 | ?14 | * |
| * | ?* | * |
According to table 1, for identical level of significance (msb in the present embodiment) even there are two models.This is because two models produce at the quantized samples that demonstrates different distributions.
To explain the processing procedure that is used to encode now in more detail according to Fig. 6 example of table 1.
The bit number of a symbol be 4 or littler situation under, according to Huffman encoding of the present invention as shown in Equation 1:
Huffman code value=Huffman code book [code book index] [more higher bit plane] [symbol] ... ... (1)
In other words, Huffman encoding uses 3 input variables, comprises code book index, more higher bit plane, and symbol.Code book index is represented the value that obtains from table 1, and more the symbol on the symbol of current expectation coding is represented to be close on the bit-planes in the higher bit plane.The symbol of encoding is expected in symbolic representation at present.
Because the msb of Huffman model is 4 in the example of Fig. 6, select 13-16 or 17-20.If the additional information that is encoded is 8,
The code book index of the symbol that is formed by the msb bit is 16,
The code book index of the symbol that is formed by the msb-1 bit is 15,
The code book index of the symbol that is formed by the msb-2 bit is 14, and
The code book index of the symbol that is formed by the msb-3 bit is 13.
Simultaneously, do not have the more data on higher bit plane,, carry out coding with the sign indicating number of Huffman code book [16] [0b] [1000b] if more the value on higher bit plane is 0 owing to receive the symbol of msb bit formation.Because the more higher bit plane of the symbol that is formed by the msb-1 bit is 1000b, carries out with the sign indicating number of Huffman code book [15] [1000b] [0010b] and to encode.Because the more higher bit plane of the symbol that is formed by the msb-2 bit is 0010b, carries out with the sign indicating number of Huffman code book [14] [0010b] [0100b] and to encode.Because the more higher bit plane of the symbol that is formed by the msb-3 bit is 0100b, carries out with the sign indicating number of Huffman code book [13] [0100b] [1000b] and to encode.
The number of bit-envelope unit 14 counting coded-bits uses the number of the bit that allows use in the layer relatively should count, if counting greater than allowing number, stops to encode.When allowing the space in following one deck, the remaining bits that is not encoded is encoded and is put into down one deck.By after whole codings, if still have living space in the number of the bit that allows in the layer, if promptly have living space in the layer, still uncoded quantized samples was encoded after then coding was finished in the low layer in the quantized samples that is assigned to equivalent layer.
Simultaneously, if the bit number of the symbol that is formed by msb uses the position on the current bit-planes to determine the Huffman code value more than or equal to 5.In other words, if validity more than or equal to 5, only has less statistical difference in the data on each bit-planes, use identical Huffman model that data are carried out Huffman encoding.In other words, all there is the Huffman pattern in each bit-planes.
If validity is more than or equal to 5, in other words, the bit number of symbol is more than or equal to 5, and Huffman encoding of the present invention satisfies formula 2:
Huffman sign indicating number=20+bpl ... 2
Wherein the index of the current bit-planes that is encoded is expected in ' bpl ' expression, and is the integer more than or equal to 1., listed as table 2, constant 20 is values that increase, and is used to represent index since 21, because the last index of Huffman model (corresponding to additional number 8) is 20.Therefore, the additional information that is used for a coding section has been represented validity simply.In table 2, determined the Huffman model by the index of the bit-planes of present encoding according to expectation.
Table 2
| Additional information | Validity | The Huffman model |
| ?9 | ?5 | 21-25 |
| ?10 | ?6 | 21-26 |
| ?11 | ?7 | 21-27 |
| ?12 | ?8 | 21-28 |
| ?13 | ?9 | 21-29 |
| ?14 | ?10 | 21-30 |
| ?15 | ?11 | 21-31 |
| ?16 | ?12 | 21-32 |
| ?17 | ?13 | 21-33 |
| ?18 | ?14 | 21-34 |
| ?19 | ?15 | 21-35 |
For quantizing factor information in the additional information and Huffman model information, on coding section, carry out DPCM corresponding to information.When the quantification factor information is encoded, in the header message of frame, represent initial DPCM value with 8 bits.The initial value that is used for the DPCM of Huffman model information is set to 0.
List according to the present invention below and the coding method of the BSAC technology of prior art between difference.At first, in the BSAC technology, coding is bitwise carried out, and is to be that unit carries out coding with the symbol in the present invention.The second, in the BSAC technology, use arithmetic coding, and used Huffman encoding in the present invention.Arithmetic coding provides higher compression gains, but has increased complicacy and cost.Therefore, in the present invention, data are not to be encoded with bit base, but are that unit is encoded by Huffman with the symbol, so that reduce complicacy and cost.
For the control bit rate, in other words for scalability is provided, be cut off corresponding to the bit stream of a frame, allow the number of the bit that uses in considering every layer, make and only utilize small amount of data but can decode.For example,, only use 1048 bits of bit stream, make it possible to obtain decoding audio data corresponding to 48kbps if only decoded corresponding to the expectation of the bit stream of 48kbps.
To explain now based on said structure according to Code And Decode method of the present invention.
Code device reads the pcm audio data, storage data (not shown) in storer, and by tonequality modeling acquisition shielding thresholding and additional information from the pcm audio data of storage.Because the pcm audio data are time-domain signals, the pcm audio data are become frequency-region signal by wavelet transform.Then, code device obtains quantized samples according to the signal that quantizes segment information and quantizing factor throughput beggar wave conversion.As mentioned above, coded quantization sample and by bit section coding encapsulates based on the coding and the Huffman encoding of symbolic unit.
Fig. 7 is a process flow diagram, is used to explain the coding method according to the preferred embodiment of the present invention.
With reference to figure 7, the present processing procedure of the sample that bit-envelope unit 14 codings and the encapsulation of interpretive code device quantized.
At first, bit-envelope unit 14 extracts information corresponding to every layer according to the target bit rate that is provided and additional information.This is handled in step 701 and carries out in to 703.More specifically, obtain as the cutoff frequency that is used for every layer the basis of ending in step 701, in quantification segment information and the coding section information of step 702 acquisition corresponding to every layer, and in step 703 allocation bit scope, in this scope, the bit that should encode can be encoded in each layer.
Then, in step 704, layer index is configured to basic unit, and additional information (comprising segment information and the coding section information of quantizing) is encoded in step 705.
Next, be mapped on the bit-planes, and be that unit encodes according to the symbol that forms by the msb bit with the 4*4 piece in step 706 corresponding to the quantized samples of basic unit.In step 707, the bit number of coding is counted, and if be somebody's turn to do counting above the bit range when anterior layer, then the coding when anterior layer is stopped, and begins coding at following one deck.If the bit number at step 707 counting does not exceed bit range, then in step 709, process turns back to step 705 to handle down one deck.Because the not lower layer of basic unit, step 708 is not performed, but at the layer execution in step of following after the basic unit 708.By above-mentioned steps, all be encoded up to the layer of all scopes of destination layer.
1. the quantized samples corresponding to a layer is the unit grouping with the N sample and is mapped on the bit-planes.
2. the symbol that forms according to the msb bit by the binary data that shines upon is carried out Huffman encoding.Substep 2 can followingly be explained in detail:
2.1 the scalar value (curVal) corresponding to the symbol of expecting coding is obtained.
2.2 the Huffman code corresponding to scalar value (upperVal) is obtained, this scalar value in other words, is in the symbol of the position higher than the symbol of expectation present encoding corresponding to the symbol in the higher bit plane more in the bit stream.
For quantizing factor information in the additional information and Huffman model information, on coding section, carry out DPCM corresponding to information.When the quantification factor information was encoded, the initial value of DPCM was represented by 8 bits in the header message of frame.The initial value that is used for the DPCM of Huffman model information is set to 0.
Fig. 8 is a process flow diagram, is used to explain the coding/decoding method according to the preferred embodiments of the present invention.
With reference to figure 8, decoding device receives the bit stream that is formed by the voice data of encoding in hierarchy, and the header message in every frame of decoding.Then, in step 801, comprise corresponding to the additional information of the scaling factor information of ground floor and encoding model information decoded.In step 802,,, obtain quantized samples by according to being unit ground decoding bit stream with the symbol up to the order of the symbol that forms by the LSB bit from the symbol that forms by the MSB bit with reference to encoding model information.In step 803, by reference scaling factor information, the quantized samples of acquisition is reversed quantification, and in step 804, the inverse quantization sample is reversed conversion.Along with each ordinal number that successively increases layer, repeated execution of steps 801-804 is up to finishing a plurality of layers predetermined coding.
Fig. 9 is a process flow diagram, is used to explain the coding/decoding method according to another preferred embodiment of the present invention.
With reference to figure 9, receive the bit stream that forms by the voice data of in hierarchy, encoding, and in step 901, according to the cutoff frequency of the decoding of the header message in every frame corresponding to every layer.In step 902, by decoding, according to quantification segment information and the coding section information of header message identification corresponding to every layer.In step 903, every layer permission uses bit range to be identified.In step 904, layer index is set to basic unit.Additional information in the step 905 decoding basic unit, in step 906, by according to being the bit range of every layer permission with symbolic unit ground with bit stream decoding up to the order of the symbol that forms by the LSB bit from the symbol that forms by the MSB bit, the acquisition quantized samples.In step 907, check when anterior layer whether last.Along with the increase one by one of the number of plies, step 905 and 906 repeats on each layer, up to arriving predetermined destination layer.In step 901-903, decoding device can have cutoff frequency in advance, quantizes segment information, coding section information and bit range, rather than obtain these information according to the header message in every frame of the bit stream that is stored in reception.In the case, by reading canned data, the decoding device acquired information.
As mentioned above, according to the present invention, by after carrying out the bit section, being the unit encoding bit with the symbol, provide so as to passing through the scalability of top-down system control bit rate, make the calculated amount of code device not too greater than the device that scalability is not provided.In other words, according to the present invention, provide a kind of method and apparatus that encoding and decoding have the voice data of scalability that is used for, wherein complicacy is lower, can provide FGS simultaneously, and good audio quality, even at low layer.
In addition, be compared to the MPEG-4 audio frequency BSAC technology of using arithmetic coding, use the coding and decoding device of the present invention of Huffman encoding to reduce to be used to encapsulate/calculated amount that deblocking is handled, it reduces to 1/8th of BSAC technology.Even when being performed according to bit-envelope of the present invention so that RGS is provided, expense is little, make coding gain identical when not providing scalability.
In addition, owing to have hierarchy according to device of the present invention, for the processing that makes server end can the control bit rate produce bit stream again is very simple, therefore, the complicacy that is used for the device of transition coding is low.
When sending audio stream by network, can be according to user's selection or network condition control transmission bit rate, so that the service that does not stop breaking can be provided.
When audio stream was stored in the information storage medium with limited capacity, the size of file can be controlled arbitrarily and is stored.If the bit rate step-down, frequency range is restrained.Therefore, be that the complicacy of the wave filter of complex appts in the coder/decoder is greatly diminished, and be inversely proportional to the actual complex reduction of coding/decoding apparatus with bit rate.
By using wavelet transform, time/frequency domain resolution is higher than the coding based on MDCT of prior art, to such an extent as to audio quality preferably is provided, even at lower level.
Claims (27)
1. method that is used for the telescopically coding audio data comprises:
From ground floor begin to encode the multilayer every layer, ordinal number is added one then at every turn, up to the coding of finishing multilayer, wherein, layer coding comprised:
Coding comprises corresponding to the scaling factor information of ground floor and the additional information of encoding model information;
By reference encoding model information,, be a plurality of quantized samples of unit encoding corresponding to ground floor with the symbol according to from the symbol that forms by highest significant position order up to the symbol that forms by least significant bit (LSB).
2. according to the process of claim 1 wherein that the section of voice data comprises:
Carry out the wavelet transform of voice data; With
By the reference cutoff frequency, the data of section wavelet transform make the data of cutting into slices corresponding to a plurality of layers.
3. according to the process of claim 1 wherein that the coding of voice data comprises differential coding scaling factor information and encoding model information.
4. according to the process of claim 1 wherein that the coding of a plurality of quantized samples comprises Huffman encoding.
5. according to the process of claim 1 wherein that the coding of a plurality of quantized samples comprises:
The a plurality of quantized samples of mapping on bit-planes; With
According to from the symbol that forms by most significant bits order, be the unit encoding sample with the symbol in the bit range that in layer, is allowed corresponding to sample up to the symbol that forms by the least significant bit (LSB) bit.
6. according to the method for claim 5, wherein when a plurality of quantized samples of mapping, K quantized samples is mapped on the bit-planes, and in the coding of sample, obtain scalar value, and pass through with reference to K bit-binary data corresponding to the symbol that forms by K bit-binary data, the scalar value that obtains, with corresponding to the scalar value that is higher than a symbol of current symbol on the bit-planes, carry out Huffman encoding, wherein K is an integer.
7. coding method comprises:
The section voice data makes the voice data of cutting into slices corresponding to a plurality of layers;
Acquisition is corresponding to a plurality of layers each calibration segment information and coding section information;
From ground floor begin to encode the multilayer every layer, ordinal number is added one then at every turn, up to the coding of finishing multilayer, wherein, layer coding comprised:
Based on calibration segment information and the coding section information corresponding to ground floor, coding comprises the additional information of scaling factor information and encoding model information;
By the voice data of reference scaling factor information quantization, obtain quantized samples corresponding to ground floor; With
By reference encoding model information,, be a plurality of quantized samples that unit encoding obtained with the symbol according to from the symbol that forms by highest significant position order up to the symbol that forms by least significant bit (LSB).
8. according to the method for claim 7, further comprise, before the additional information of coding,
The bit range that acquisition is allowed in each of a plurality of layers, wherein when a plurality of quantized samples that coding is obtained, the number of the bit of coding is counted, if and the bit of counting outnumber bit range corresponding to this bit, coding stops, even and after quantized samples is encoded entirely, if the number of bit of counting less than bit range corresponding to this bit, still uncoded bit is encoded into the scope of bit range permission after the low layer coding is done.
9. method that is used for telescopically decoding with the voice data of hierarchy coding comprises:
Begin the decoding multi-layer every layer from ground floor, ordinal number added one then at every turn,, wherein, layer decoder is comprised up to the decoding of finishing multilayer:
Decoding comprises corresponding to the scaling factor information of ground floor and the additional information of encoding model information;
By reference encoding model information, according to from the symbol that forms by most significant bits order, be the unit decoding audio data, and obtain quantized samples with the symbol up to the symbol that forms by the least significant bit (LSB) bit;
The quantized samples that is obtained by reference scaling factor information inverse quantization; With
The sample of this inverse quantization of reciprocal transformation.
10. according to the method for claim 9, wherein the decoding of additional information comprises differential decoding scaling factor information and encoding model information.
11., wherein when decoding audio data, obtain quantized samples by Huffman decoding according to the method for claim 9.
12. according to the method for claim 9, wherein the decoding of voice data further comprises:
According to from the symbol that forms by most significant bits order, be the unit decoding audio data with the symbol in the bit range that in layer, is allowed corresponding to voice data up to the symbol that forms by the least significant bit (LSB) bit; With
Arranged the bit-planes of decoding symbols to obtain quantized samples from it.
13., wherein when decoding audio data, obtain the 4*K bit-planes that forms by decoding symbols, and from the quantized samples that obtains, from K quantized samples of 4*K bit-planes acquisition, wherein K is an integer according to the method for claim 12.
14. a device that is used for the telescopically decoding with the voice data of hierarchy coding comprises:
The deblocking unit, its decoding comprises corresponding to the scaling factor information of ground floor and the additional information of encoding model information, and pass through with reference to encoding model information, according to from the symbol that forms by most significant bits order up to the symbol that forms by the least significant bit (LSB) bit, with the symbol is the unit decoding audio data, and obtains quantized samples;
The inverse quantization unit, its quantized samples by being obtained with reference to scaling factor information inverse quantization; With
The reciprocal transformation unit, this inverse quantization sample of its reciprocal transformation.
15. according to the device of claim 14, wherein deblocking unit differential decoding scaling factor information and encoding model information.
16. according to the device of claim 14, wherein quantized samples is exported by Huffman decoding in the deblocking unit.
17. device according to claim 14, wherein the deblocking unit is according to from the symbol that formed by the most significant bits order up to the symbol that is formed by the least significant bit (LSB) bit, in corresponding to the layer of voice data, be the unit decoding audio data with the symbol in the bit range that allowed, arranged the bit-planes of decoding symbols to obtain quantized samples from it.
18. according to the device of claim 15, wherein the deblocking unit obtains the 4*K bit-planes that formed by decoding symbols, and from K quantized samples of 4*K bit-planes acquisition, wherein K is an integer.
19. a device that is used for the telescopically coding audio data comprises:
The converter unit of converting audio frequency data;
Quantifying unit, it quantizes the converting audio frequency data corresponding to every layer by with reference to scaling factor information,
And output quantized samples; With
Encapsulation unit, its coding comprises corresponding to the scaling factor information of ground floor and the additional information of encoding model information, by reference encoding model information, according to from the symbol that forms by highest significant position order, be a plurality of quantized samples of unit encoding from quantifying unit with the symbol up to the symbol that forms by least significant bit (LSB).
20. device according to claim 19, wherein encapsulation unit obtains each calibration segment information and the coding section information corresponding to a plurality of layers, and based on the additional information that comprises scaling factor information and encoding model information corresponding to every layer calibration segment information and coding section information coding.
21. device according to claim 19, wherein encapsulation unit is counted the number of the bit of coding, if and the bit of counting outnumber bit range corresponding to this bit, coding stops, even and after quantized samples is encoded entirely, if the number of the bit of counting is less than the bit range corresponding to this bit, still uncoded bit is encoded into the scope that bit range allows after the coding of low layer is finished.
22. according to the device of claim 19, wherein converter unit is executed in wave conversion to voice data.
23. according to the device of claim 19, wherein encapsulation unit makes the data of cutting into slices corresponding to a plurality of layers by the data with reference to cutoff frequency section wavelet transform.
24. according to the device of claim 19, wherein encapsulation unit differential coding scaling factor information and encoding model information.
25. according to the device of claim 19, encapsulation unit Huffman encoding quantized samples wherein.
26. device according to claim 25, wherein encapsulation unit shines upon a plurality of quantized samples on bit-planes, and according to from the symbol that forms by most significant bits order, be the unit encoding sample with the symbol in the bit range that in layer, is allowed corresponding to sample up to the symbol that forms by the least significant bit (LSB) bit.
27. device according to claim 25, wherein encapsulation unit shines upon K quantized samples on bit-planes, acquisition is corresponding to the scalar value of the symbol that is formed by K bit-binary data, and pass through with reference to K bit-binary data, the scalar value that obtains, with carry out Huffman encoding corresponding to the scalar value that is higher than a symbol of current symbol on the bit-planes, wherein K is an integer.
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| KR20070038699A (en) * | 2005-10-06 | 2007-04-11 | 삼성전자주식회사 | Scalable bsac(bit sliced arithmetic coding) audio data arithmetic decoding method and apparatus |
| CN102014285B (en) * | 2009-11-10 | 2012-10-03 | 钰创科技股份有限公司 | Multiple-error signal coding device and method |
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| KR100261253B1 (en) * | 1997-04-02 | 2000-07-01 | 윤종용 | Scalable audio encoder/decoder and audio encoding/decoding method |
| KR100261254B1 (en) * | 1997-04-02 | 2000-07-01 | 윤종용 | Scalable audio data encoding/decoding method and apparatus |
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