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WO2007035070A1 - Procede et appareil d'amelioration de l'efficacite du codage entropique et procede de codage video, et appareil utilisant ce procede - Google Patents

Procede et appareil d'amelioration de l'efficacite du codage entropique et procede de codage video, et appareil utilisant ce procede Download PDF

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Publication number
WO2007035070A1
WO2007035070A1 PCT/KR2006/003812 KR2006003812W WO2007035070A1 WO 2007035070 A1 WO2007035070 A1 WO 2007035070A1 KR 2006003812 W KR2006003812 W KR 2006003812W WO 2007035070 A1 WO2007035070 A1 WO 2007035070A1
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WIPO (PCT)
Prior art keywords
coefficients
variable length
decoding
grouping
fgs
Prior art date
Application number
PCT/KR2006/003812
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English (en)
Inventor
Bae-Keun Lee
Woo-Jin Han
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Samsung Electronics Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from KR1020060003321A external-priority patent/KR100714706B1/ko
Application filed by Samsung Electronics Co., Ltd. filed Critical Samsung Electronics Co., Ltd.
Priority to JP2008528961A priority Critical patent/JP2009506710A/ja
Priority to EP06798895A priority patent/EP1929782A4/fr
Publication of WO2007035070A1 publication Critical patent/WO2007035070A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/60—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding
    • H04N19/625—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding using discrete cosine transform [DCT]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
    • H04N19/136—Incoming video signal characteristics or properties
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/184—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being bits, e.g. of the compressed video stream
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/187—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being a scalable video layer
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/30—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using hierarchical techniques, e.g. scalability
    • H04N19/34—Scalability techniques involving progressive bit-plane based encoding of the enhancement layer, e.g. fine granular scalability [FGS]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/60—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding
    • H04N19/61—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding in combination with predictive coding
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/13—Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC]

Definitions

  • Apparatuses and methods consistent with the present invention relate to a video coding technique, and more particularly, to a method and apparatus of enhancing the performance of entropy coding in a multilayer-based codec system.
  • Multimedia data requires a large capacity of storage media and a wide bandwidth for transmission since the amount of multimedia data is usually large. Accordingly, a compression coding method is a requisite for transmitting multimedia data including text, video, and audio.
  • a basic principle of data compression lies in removing data redundancy.
  • Data may be compressed by removing spatial redundancy in which the same color or object is repeated in an image, temporal redundancy in which there is little change between adjacent frames in a moving image or the same sound is repeated in audio, or mental visual redundancy taking into account human eyesight and limited perception of high frequency.
  • temporal redundancy is removed by temporal filtering based on motion compensation
  • spatial redundancy is removed by spatial transformation.
  • Redundancy-removed data is again subjected to quantization for lossy coding using a predetermined quantization step.
  • the quantized data is finally subjected to entropy coding for lossless coding.
  • Standardization work for implementation of multilayer-based coding techniques using the H.264 standard is being actively pursued at present by a joint video team (JVT) of ISO/IEC (International Organization for Standardization / International Elec- trotechnical Commission) and ITU (International Telecommunication Union).
  • JVT joint video team
  • ISO/IEC International Organization for Standardization / International Elec- trotechnical Commission
  • ITU International Telecommunication Union
  • Entropy coding techniques currently being used in the H.264 standard include
  • CAVLC Context- Adaptive Variable Length Coding
  • CABAC Context- Adaptive Binary Arithmetic Coding
  • Exp_Golomb Exponential Golomb
  • Table 1 shows entropy coding techniques used for each to-be-coded parameter under the H.264 standard.
  • Exp_Golomb is used in coding the macroblock type indicating whether a corresponding macroblock in an inter-prediction mode or intra-prediction mode, the macroblock pattern specifying the types of a subblocks that form a macroblock, the quantization parameter which is an index to determine a quantization step, the reference flame index specifying the frame number which is referred to in an inter-prediction mode, and the motion vector, while CAVAC is used in coding the residual data defining a difference between an original image and a predicted image.
  • VLC Very Length Coding
  • CAVLC Variable Length Coding
  • JVT-P056 A new VLC technique that takes SVC characteristics into consideration has been proposed in an article by J. Ridge and M. Karczewicz, entitled 'Variable length code for SVC, Poznan, in the 16th JVT meeting (JVT-P056).
  • JVT-P056 the same procedure as in the H.264 standard is used in a discrete layer, while VLC techniques based on different probability characteristics are used in FGS layers.
  • JSVM Joint Scalable Video Model
  • FGS fine granular scalability
  • JVT-P056 proposed a VLC technique for FGS layers. According to the proposed
  • VLC technique during coding of refinement coefficients (refinement bits) in a refinement pass, every four refinement bits, suggesting the use of a fixed number of refinement bits, are grouped as a group to form a symbol, which is then coded using a single VLC table.
  • This technique is, however, not an efficient coding technique in view of the fact that the FGS layers have different distributions of zeros in the respective FGS layers. Disclosure of Invention
  • FIG. 1 illustrates non-zero proportions for each fine granular scalability (FGS) layer when a single VLC table is used in a refinement pass.
  • FGS fine granular scalability
  • an aspect of the pre sent invention provides a method and apparatus for enhancing the performance of entropy coding by allowing a grouping unit and a variable length coding ( VLC) table corresponding thereto to be adaptively selected according to characteristics of each fine granular scalability (FGS) layer in a refinement pass among scanning passes.
  • VLC variable length coding
  • a variable length coding method for lossless-coding first coefficients among coefficients of a discrete layer and one or more fine granular scalability (FGS) layers including determining a proportion of zeros included in a predetermined unit region to which the first coefficients belong, selecting one of a plurality of grouping units depending on whether or not the proportion exceeds a predetermined threshold, grouping absolute values of the first coefficients using the selected grouping unit, and transforming the grouped absolute values into a code word mapped thereto by referring to a VLC table corresponding to the selected group unit.
  • FGS fine granular scalability
  • a variable length decoding method for decoding first coefficients of a fine granular scalability (FGS) layer in input bitstreams by losslessly decoding a first bitstream of the FGS layer, the method including determining a proportion of zeros included previously decoded second coefficients in a predetermined unit region to which the first coefficients belong, selecting one of a plurality of grouping units depending on whether or not the proportion exceeds a predetermined threshold, and decoding the first coefficients from a code word included in the first bitstream by referring to a VLC table corresponding to the selected group unit.
  • FGS fine granular scalability
  • variable length decoding method for decoding refinement coefficients of a fine granular scalability (FGS) layer in input bitstreams by losslessly decoding a first bitstream of the FGS layer, the method including reading information about a grouping unit interleaved into the first bitstream for each predetermined unit region, fetching a VLC table corresponding to the grouping unit, and decoding the first coefficients from a code word included in the first bitstream by referring to the VLC table corresponding to the group unit.
  • FGS fine granular scalability
  • a variable length coding apparatus for lossless-coding first coefficients among coefficients of a discrete layer and one or more fine granular scalability (FGS) layers, the apparatus including means that determines a proportion of zeros included in a predetermined unit region to which the first coefficients belong, means that selects one of a plurality of grouping units depending on whether the proportion exceeds a predetermined threshold or not, means that groups absolute values of the first coefficients using the selected grouping unit, and means that transforms the grouped absolute values into a code word mapped thereto by referring to a VLC table corresponding to the group unit.
  • FGS fine granular scalability
  • a variable length decoding apparatus for decoding first coefficients of a fine granular scalability (FGS) layer in input bitstreams by losslessly decoding a first bitstream of the FGS layer, the apparatus including means that determines a proportion of zeros included in previously decoded second coefficients in a predetermined unit region to which the first coefficients belong, means that selects one of a plurality of grouping units depending on whether or not the proportion exceeds a predetermined threshold, and means that decodes the first coefficients from a code word included in the first bitstream by referring to a VLC table corresponding to the selected group unit.
  • FGS fine granular scalability
  • FIG. 1 illustrates non-zero proportions for each fine granular scalability (FGS) layers in case of using a single VLC table in a refinement pass;
  • FlG. 2 illustrates an example of separately representing quantization coefficients in a discrete layer and one or more FGS layers
  • FlG. 3 is a block diagram of a refinement bit encoder in accordance with one embodiment of the present invention.
  • FlG. 4 is a block diagram of a refinement bit decoder in accordance with one embodiment of the present invention.
  • FlG. 5 is a block diagram of an FGS video encoder in which an entropy encoder shown in FlG. 3 may be employed.
  • FlG. 6 is a block diagram of an FGS video decoder in which an entropy decoder shown in FlG. 4 may be employed.
  • the present invention allows a grouping unit and a variable length coding ( VLC) table corresponding thereto to be adaptively selected on the basis of the number of zeros included in a unit region, e.g., frame, slice, macroblock, or block.
  • the grouping unit means the number of refinement bits forming a symbol.
  • FlG. 2 illustrates an example of separately representing quantization coefficients in a discrete layer and one or more FGS layers.
  • each layer is indicated by blocks each having 4x4 coefficients.
  • Values labeled at corresponding locations are combined to represent a quantization coefficient.
  • a reduction of a bit rate can be achieved by truncating the layers from the highest FGS layer. In this case, only some of the coefficients in a layer may be truncated.
  • coefficients located at the second row of the first column are 3, -1, and 1.
  • all the coefficients located thereat are necessary.
  • 1, or 1 and -1 may be truncated, and only coefficients of the lower layer are used in a decoder to decode the quantization coefficients.
  • a loss is generated.
  • the FGS layers express difference values.
  • values other than the values of 0, 1, and -1 are expressed in the discrete layer, only the values of 0, 1, and -1 are expressed in the FGS layers.
  • the coefficients of the FGS layers are coded in the significance pass when the corresponding coefficient of the discrete layer is 0, and the coefficients of the FGS layers are coded in the refinement pass when the corresponding coefficient of the discrete layer is not 0.
  • shaded bits in the first FGS layer i.e., refinement bits, are coded in the refinement pass.
  • the adaptive VLC method according to the present invention is particularly suitably adopted for the refinement pass.
  • VLC-coding coefficients of a discrete layer both levels and trailing ones should be encoded.
  • VLC-coding refinement coefficients since the levels and trailing ones are not necessarily taken into consideration, it is advantageous and desirable to employ a more efficient, simple VLC method.
  • FIG. 3 is a block diagram of a refinement bit encoder 100 in accordance with one embodiment of the present invention.
  • a selecting portion 120 determines a grouping unit to be used in the grouping portion 110 by referring to the refinement bit of the previously coded unit region.
  • the unit region may be a frame, a slice, a macro block, or a block to which the input refinement bit belongs.
  • the grouping unit 120 counts the number of zeros in bits of the unit region. If the proportion of zeros in the bits of the unit region exceeds a predetermined threshold, the grouping unit is set to 4, as proposed in the JVT-P056. However, if the proportion of zeros in the bits of the unit region does not exceed the predetermined threshold, the grouping unit is set to 3. If quite a large number of zeros occur in the bits to be coded, several zeros may be grouped and expressed as a short code word. Accordingly, it is advantageous to set the grouping unit to a relatively large number. Conversely, if the number of zeros occurring in the bits to be coded is small, the grouping unit is advantageously set to a relatively small number.
  • the selecting portion 120 of the present invention is configured to adjustably select a grouping unit.
  • one threshold and two grouping units are used by way of example, but the present invention is not limited thereto.
  • 11 will be understood by those of ordinary skill in the art that n thresholds and n+1 grouping units can be generally used, where n is a natural number .
  • the thresholds can be empirically or experimentally determined values, for example, 7/8, 3/4, or 2/3.
  • a VLC table proposed in the JVT-P056, i.e., Table 2 is supplied to the magnitude coding portion 130.
  • a VLC table proposed in the present invention i.e., Table 3 is supplied to the magnitude coding portion 130.
  • the symbol is the absolute value of a string grouped by every four refinement bits, and the code word is a mapping result of the symbol.
  • the grouping portion 110 groups the input refinement bits into groups using a grouping unit supplied from the selecting portion 120.
  • the absolute value (1 or 0) of the grouped refinement bits is supplied to the magnitude coding portion 130, and symbols of the respective refinement bits (excluding 0) are supplied to the symbol coding portion 150.
  • the table storage portion 140 stores VLC tables and supplies the magnitude coding portion 130 with a VLC table corresponding to the grouping unit selected by the selecting portion 120.
  • the table storage portion 140 may be a nonvolatile memory such as ROM, PROM, EPROM, EEPROM, flash memory, etc., a volatile memory such as RAM, a storage medium such as a hard disk, or any other medium which is suitable for this purpose .
  • the magnitude coding portion 130 transforms the absolute value, that is, a symbol, of the grouped refinement bits supplied from the grouping portion 110 into a code word, by referring to the VLC table supplied from the table storage portion 140.
  • the symbol coding portion 150 codes the symbol supplied from the grouping portion 110 into a 1-bit symbol code. Generally, the symbol code with a positive symbol is coded into 0 and the symbol code with a negative symbol is coded into 1.
  • the multiplexer (Mux) 160 multiplexes a set of code words output from the magnitude coding portion 130 and a set of code words output from the symbol coding portion 150 to generate a bitstream. For example, assuming that a refinement bit set to be encoded is ⁇ -1, 0, 1, 1, 0, 0, 1, -1 ⁇ , a refinement bit encoding process will now be described.
  • the proportion selecting portion 120 selects the grouping unit as 3.
  • the grouping portion 110 groups a set of the refinement bits into several groups each consisting of three bits, and the absolute values 101, 100, and 110, 11 preceded by 0 added to adjust the unit of the number of zeros, are supplied to the magnitude coding portion 130, and the symbols ⁇ -, +, +, +, - ⁇ are supplied to the symbol coding portion 150, respectively.
  • the magnitude coding portion 130 receives a VLC table, i.e., Table 3, from the table storage portion 140, and transforms the 101, 100, and 110 into a corresponding code word by referring to Table 3.
  • a value 1011001101 is output from the magnitude coding portion 130 and input to the Mux 160.
  • the symbol coding portion 150 transforms the symbols ⁇ -, +, +, +, - ⁇ into a code word 10001.
  • the transformation result 10001 may further be run-level coded.
  • the Mux 160 multiplexes 1011001101 with 10001 and outputs a multiplexing result.
  • the proportion selecting portion 120 selects the grouping unit as 4.
  • the grouping portion 110 groups a set of the refinement bits into several groups each consisting of four bits, and the absolute values 1011, and 0011 are supplied to the magnitude coding portion 130, and the symbols ⁇ -, +, +, +, - ⁇ are supplied to the symbol coding portion 150, respectively.
  • the magnitude coding portion 130 receives a VLC table, i.e., Table 2, from the table storage portion 140, and transforms the absolute values 1011 and 0011 into corresponding code words by referring to Table 2. As a result, a value 11110111000 is output from the magnitude coding portion 130 and input to the Mux 160. Meanwhile, the symbol coding portion 150 transforms the symbols ⁇ -, +, +, +, - ⁇ into a code word 10001. The transformed result 10001 may further be run-level coded. Then, the Mux 160 multiplexes 11110111000 with 10001 and outputs a multiplexing result.
  • a VLC table i.e., Table 2
  • FlG. 4 is a block diagram of a refinement bit decoder 200 in accordance with one embodiment of the present invention, the refinement bit decoder 200 corresponding to the refinement bit encoder 100 shown in FlG. 3 .
  • input bitstreams are separated into a set of code words and a set of symbol codes by a demultiplexer (Demux) 210.
  • the set of code words and the set of symbol codes are supplied to a magnitude decoding portion 230 and a symbol decoding portion 250, respectively.
  • a selecting portion 220 counts a proportion of zeros in refinement bits of the previously decoded unit region and selects one of two grouping units depending on whether the proportion of zeros in the refinement bits of the unit region exceeds a predetermined threshold or not.
  • a plurality of grouping units may be set.
  • the selecting portion 220 may select three or more grouping units.
  • the magnitude decoding portion 230 reads the VLC table corresponding to the selected grouping unit, i.e., Table 2 or 3, from the table storage portion 240, and continues to read bits of the set of the code word until the same value as any one of code words of the VLC table occurs. If a given number of the bits read from the VLC table is the same as a certain code word, a symbol corresponding to the certain code word is decoded.
  • the selected grouping unit i.e., Table 2 or 3
  • the decoded symbol is supplied to the symbol decoding portion 250. Then, the symbol decoding portion 250 reads the symbol codes supplied from the Demux 210 one by one, and sequentially assigns symbols corresponding to the symbol codes am ong symbols supplied from the magnitude decoding portion 230 to non-zero symbols, i.e., 1. In such a manner, the current refinement bits are decoded from the bitstream.
  • the Demux 210 separates 11110111000 and 10001 from the bitstream to then be supplied to the magnitude decoding portion 230 and the symbol decoding portion 250, respectively.
  • the selecting portion 220 confirms that the number of zeros in the refinement bits of the previously restored unit region exceeds a predetermined threshold and causes the table storage portion 240 to supply the magnitude decoding portion 230 with the VLC table, i.e., Table 2.
  • the magnitude decoding portion 230 reads the bitstream 11110111000 one bit by one bit until the same code word as any one of the code words listed in Table 2 occurs.
  • the magnitude decoding portion 230 checks with the next code word 111101. Since the same code word 111101 is listed in Table 2, the corresponding symbol 1011 is decoded. In the same manner, 0011 is decoded from the remaining bits 11000. As a result, a value 10110011 is output from the magnitude decoding portion 230 and input to the symbol decoding portion 250. The symbol decoding portion 250 decodes symbols ⁇ -, +, +, +, - ⁇ corresponding to the value 10001 supplied from the magnitude decoding portion 230, and assigns the same to non-zero values among input bits 10110011. Finally, the first input to the encoder 100, i.e., the set of the refinement bits ⁇ -1, 0, 1, 1, 0, 0, 1, -1 ⁇ is decoded.
  • the refinement bit decoder 200 selects one of a plurality of grouping units in a similar process to that of the encoder 100, but the invention is not limited thereto. Since a part of an FGS layer may be truncated before being transmitted to the refinement bit decoder 200, different grouping units may be selected at an encoder and a decoder using ambient characteristics within a unit region containing a current block.
  • the grouping unit selected in the refinement bit encoder 100 is interleaved into a bitstream and transmitted to the refinement bit decoder 200.
  • the grouping unit may be selected in a unit region, that is, in units of frames, slices, macroblocks, or blocks.
  • the unit region is preferably in units of slices or macroblocks.
  • a token for indicating the selected VLC table may be transmitted in a slice header or a macroblock header.
  • the refinement bit decoder 200 can fetch the VLC table corresponding to the grouping unit directly from the table storage portion 240.
  • the selecting portion 220 may not be provided.
  • FIG. 5 is a block diagram of an FGS video encoder 1000 in which an entropy encoder as shown in FIG. 3 can be employed.
  • An original video sequence is input into an enhancement layer encoder 600. Also, when there is a difference in the resolution between layers, the original video sequence is subjected to downsampling by a downsampler 550 and the downsampled video sequence is input to a base layer encoder 500.
  • a predictor 610 subtracts an image predicted using a predetermined prediction technique from a current macroblock to obtain a residual signal.
  • Directional intra- prediction, inter-prediction, intra-BL prediction, and residual prediction may be used for prediction.
  • a transformer 620 transforms the residual signal into a transform coefficient using a spatial transform such as Discrete Cosine Transform (DCT) or wavelet transform.
  • DCT Discrete Cosine Transform
  • a quantizer 630 quantizes the transform coefficient using a predetermined quantization step (as a quantization step size increases, the level of data loss or compression ratio increases) to generate a quantization coefficient.
  • the base layer encoder 500 includes a predictor 510, a transformer 520, and a quantizer 530 having the same functions as their counterparts in the enhancement layer encoder 600. However, unlike the predictor 610, the predictor 510 cannot use Intra-BL prediction nor residual prediction.
  • An entropy encoder 640 losslessly encodes the quantization coefficient to produce an FGS layer bitstream.
  • an entropy encoder 540 losslessly encodes a quantization coefficient into a base layer bitstream.
  • a multiplexer (Mux) 650 multiplexes the FGS layer bitstream with the base layer bitstream into a bitstream to be sent to a video decoder.
  • the entropy encoder 640 may include the refinement bit encoder 100 shown in
  • the entropy encoder 640 functioning as the refinement bit encoder 100 performs lossless coding on quantization coefficients of FGS layers, specifically zero coefficients, that is, refinement bits, of a corresponding discrete layer. In this case, the entropy encoder 640 receives refinement bits contained in a unit region from the quantizer 630.
  • FIG. 6 is a block diagram of an FGS video decoder 2000 in which an entropy decoder as shown in FIG. 4 can be employed.
  • Input bitstreams are separated into an FGS bitstream and a base layer bitstream by a demultiplexer (Demux) 860 to then be supplied to an enhancement layer decoder 800 and a base layer decoder 700, respectively.
  • a demultiplexer (Demux) 860 to then be supplied to an enhancement layer decoder 800 and a base layer decoder 700, respectively.
  • An entropy decoder 810 performs a lossless decoding operation by a counterpart method used in the entropy encoder 640 to decode a quantization coefficient.
  • An inverse quantizer 820 inversely quantizes the decoded quantization coefficient according to a quantization step used by the quantizer 630.
  • An inverse transformer 830 inversely transforms the inversely quantized coefficient using an inverse transform technique such as inverse DCT or inverse wavelet.
  • An inverse predictor 840 obtains a predicted image by means of the same technique used by the predictor 610 and adds the predicted image to the inversely transformed result to decode a video sequence.
  • the base layer decoder 700 may include an entropy decoder 710, an inverse quantizer 720, an inverse transformer 730, and an inverse predictor 740 having the same functions as their counterparts in the enhancement layer decoder 800.
  • the entropy decoder 810 may include the refinement bit decoder 200 shown in
  • the entropy decoder 810 functioning as the refinement bit decoder 200 performs lossless coding on quantization coefficients of FGS layers, specifically zero coefficients, that is, refinement bits, of a corresponding discrete layer. In this case, the entropy decoder 810 uses refinement bits contained in a previously entropy-decoded unit region.
  • the components shown in FIGS. 2 through 6 may be implemented in software such as a task, class, sub-routine, process, object, execution thread or program, which is performed on a certain memory area , and/or hardware such as Field Programmable Gate Array (FPGA) or Application Specific Integrated Circuit (ASIC) .
  • the components may also be implemented in a combination of software and hardware. Further, the components may advantageously be configured to reside on computer- readable storage media, or to execute on one or more processors.
  • the present invention can enhance the performance of entropy coding in a multilayer-based codec system, thereby providing for an improved video quality in a given quantity of bits.

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  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Discrete Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Compression, Expansion, Code Conversion, And Decoders (AREA)
  • Compression Or Coding Systems Of Tv Signals (AREA)

Abstract

L'invention concerne un procédé et un appareil d'amélioration de l'efficacité du codage entropique dans un système codec basé sur plusieurs couches. Dans un procédé de codage à longueur variable pour premiers coefficients de codage sans perte parmi des coefficients d'une couche discrète et d'au moins une couche de variabilité à granularité fine (FGS), le procédé de codage à longueur variable consiste à déterminer une proportion de zéros compris dans une région d'unité prédéterminée, à laquelle appartiennent les premiers coefficients, sélectionner une unité de groupement parmi une pluralité d'unités de groupement en fonction de l'excès ou non d'un seuil prédéterminé par la proportion, grouper des valeurs absolues des premiers coefficients à l'aide de l'unité de groupement sélectionnée et à transformer les valeurs absolues groupées en un mode de code mappé par référence à un tableau VLC correspondant à l'unité de groupe sélectionnée.
PCT/KR2006/003812 2005-09-26 2006-09-25 Procede et appareil d'amelioration de l'efficacite du codage entropique et procede de codage video, et appareil utilisant ce procede WO2007035070A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP2008528961A JP2009506710A (ja) 2005-09-26 2006-09-25 エントロピコーディングの性能向上方法および装置、前記方法を利用したビデオコーディング方法および装置
EP06798895A EP1929782A4 (fr) 2005-09-26 2006-09-25 Procede et appareil d'amelioration de l'efficacite du codage entropique et procede de codage video, et appareil utilisant ce procede

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Application Number Priority Date Filing Date Title
US71996705P 2005-09-26 2005-09-26
US60/719,967 2005-09-26
KR10-2006-0003321 2006-01-11
KR1020060003321A KR100714706B1 (ko) 2005-09-26 2006-01-11 엔트로피 코딩의 성능 향상 방법 및 장치, 상기 방법을이용한 비디오 코딩 방법 및 장치

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