JP2014068247A - Code amount calculation device and program and moving image encoder and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently obtain a code amount when a moving image is encoded.SOLUTION: A moving image encoder includes a code amount calculation device which calculates a code amount of a code outputted from entropy encoding means on the basis of a series of a binary code string on a residual signal between a target image and a prediction image and encoding information such as prediction information and a series of a context variable on the encoding information. The code amount calculation device includes: means for storing initial section width when processing starts; means for holding section width updated with the initial section width as an initial value; means for controlling state transition of the section width which is held in accordance with the series of the binary code string and the series of the context variable; means for counting the number of bit-shifting times of the section width by normalization for each binary code string; and means for calculating the code amount outputted from the entropy encoding means on the basis of a code amount corresponding to a count value and the initial section width and a code amount corresponding to the section width held when the processing is terminated.

Description

  The present invention relates to a code amount calculation device and program, and a moving image encoding device and program. The present invention can be applied to processing of a moving image compression code by a moving image encoding technique such as H.264 / MPEG-4AVC.

  Conventionally, H.M. In video information compression encoding processing using video encoding technology represented by H.264 / MPEG-4AVC (hereinafter simply referred to as “H.264”), motion compensation is performed for each processing unit obtained by dividing an input image. The prediction residual signal that is the difference between the predicted image that has been predicted and the input image is quantized with a transform coefficient obtained by performing spatial transformation such as discrete cosine transformation, and this is further entropy code such as arithmetic code To achieve highly efficient video compression.

  When quantization noise is generated by the conventional quantization process, distortion occurs in the decoded image reproduced on the decoding side, but the amount of information to be encoded is reduced by quantization. In the conventional quantization process, quantized coefficient information and the like are encoded by entropy encoding such as an arithmetic code so as to have a code amount corresponding to the occurrence probability of information. For example, H.M. In H.264, a context adaptive binary arithmetic code called CABAC (Context-based Adaptive Binary Arithmetic Coding) is used.

  In the conventional video encoding technique, there is a rate distortion optimization technique as a technique for evaluating such a trade-off between distortion and code amount (rate) and using it for selecting an encoding mode. The rate distortion optimization technique refers to a distortion D with respect to a target image of a decoded image obtained when the option is selected, and a code amount R generated when the option is encoded. Thus, by selecting such that the RD cost J (J = D + λR) represented by the Lagrangian multiplier λ is minimized, the rate / distortion tradeoff is the optimum encoding method.

  For example, when selecting from a plurality of encoding mode candidates (intra mode, inter mode, skip mode, etc.) in a certain encoding unit (macroblock, etc. in H.264), it occurs when encoding with that option In this case, in the prior art, it is necessary to obtain the code amount by actually encoding.In addition, as in the technique described in Patent Document 1, the context variable may be There is a method of estimating a code amount by obtaining a code amount corresponding to each probability state to be represented by table lookup and cumulatively adding the table lookup results.

JP 2008-11431 A

  However, in the method of actually performing the encoding as in the conventional encoding technique, the amount of calculation such as processing for obtaining the output bit pattern is large, and the processing is wasted. Furthermore, in the prior art, only the number of bits with integer precision can be obtained as the code amount, and the feature that enables encoding that is not the integer code length of the arithmetic code cannot be effectively reflected in mode selection or the like.

  In addition, in the method of adding using a code amount table as in the technique described in Patent Document 1, since the approximation related to the distribution of the interval width of the arithmetic code is used, it is possible to estimate the code amount with high accuracy. Therefore, there has been a problem that optimal selection with higher encoding efficiency may not be made.

  In view of the above-described problems, a code amount calculation device and program, and a moving image encoding device and program capable of efficiently obtaining a code amount when encoding a moving image are desired.

  The first aspect of the present invention relates to a sequence of binary code sequences related to encoding information such as a residual signal and prediction information between a target image constituting a moving image and a predicted image of the target image, and the encoding information. When encoding the moving image using entropy encoding means for performing entropy encoding of the encoded information based on a context variable sequence representing each probability state of the binary code string, In the code amount calculation device for calculating the code amount of the code output by the entropy encoding means, (1) an initial interval width storage means for storing an initial interval width at the start of processing related to the binary code string sequence; (2) section width holding means for setting the initial section width as an initial value and holding a section width updated in accordance with the binary code string sequence; and (3) the binary code string series and the context variable. Depending on the series A binary code string processing means for controlling the state transition of the section width of the section width holding means; and (4) the number of bit shifts for counting the number of times that the binary code string processing means has bit-shifted the section width by the normalization process. (5) a count value of the bit shift number counting means, a code amount corresponding to the initial interval width, and the interval at the end of processing of all binary code sequences related to the binary code sequence And calculating means for calculating the code amount output from the entropy encoding means based on the code amount corresponding to the section width held by the width holding means.

  The code amount calculation apparatus according to the first aspect of the present invention includes: “a sequence of binary code sequences related to an error signal between a target image constituting a moving image and a predicted image of the target image; and the error signal. When encoding the moving image using entropy encoding means for performing entropy encoding of the error signal based on a sequence of context variables representing respective probability states of the binary code sequence, In the code amount calculation apparatus for calculating the code amount of the code output by the entropy encoding means, (1) an initial section width at the start of processing related to the binary code sequence is set as an initial value, and the binary code sequence (2) section width state transition of the section width holding means according to the binary code string series and the context variable series; Binary to control Sequence processing means; (3) normalization processing means for normalizing the section width updated by the section width holding means by bit shift for each of the binary code strings; and (4) the normalization. A bit shift number count unit for counting the number of times the bit shift is performed; (5) a count value of the bit shift number count unit; a code amount corresponding to the initial interval width; and a sequence of the binary code string Calculation means for calculating the code amount output from the entropy encoding means based on the code amount corresponding to the section width held by the section width holding means at the end of processing of all binary code strings according to The code amount calculation apparatus characterized by the above. "

  The second aspect of the present invention is a binary code sequence related to encoding information such as a residual signal or prediction information between a target image constituting a moving image and a predicted image of the target image, and a binary code related to the encoded information. When entropy coding means for performing entropy coding of the coded information based on a sequence of context variables representing each probability state of the code string, and when encoding a moving image by the entropy coding means, A code amount calculating means for estimating a required code amount, wherein the entropy encoding means outputs a code relating to encoding information selected based on the estimation result of the code amount calculating device. In the encoding apparatus, the code amount calculation apparatus according to the first aspect of the present invention is applied as the code amount calculation means.

  The third aspect of the present invention is a binary code sequence related to encoding information such as a residual signal and prediction information between a target image constituting a moving image and a predicted image of the target image, and a binary code related to the encoded information. When encoding the moving image using entropy encoding means for performing entropy encoding of the encoded information based on a sequence of context variables representing each probability state of the code string, the entropy code In the code amount calculation program for calculating the code amount of the code output by the converting means, the computer includes (1) an initial interval width storage means for storing an initial interval width at the start of processing related to the binary code string sequence; (2) Section width holding means for setting the initial section width as an initial value and holding a section width updated in accordance with the binary code string sequence; and (3) the binary code string sequence and the context Variable A binary code string processing means for controlling the state transition of the section width of the section width holding means according to the sequence; and (4) the number of times that the binary code string processing means bit-shifts the section width by the normalization process. And (5) a count value of the bit shift number counting means, a code amount corresponding to the initial interval width, and all binary code strings related to the binary code string series It is made to function as calculation means for calculating the code amount output from the entropy encoding means based on the code amount corresponding to the interval width held by the interval width holding means at the end of the process.

A moving picture coding program according to a fourth aspect of the present invention provides a computer, (1) a binary signal relating to coding information such as a residual signal and prediction information between a target image constituting a moving picture and a predicted picture of the target picture. Entropy coding means for performing entropy coding of the coded information based on the code string and a sequence of context variables representing respective probability states of the binary code string related to the coded information; (2) the above When the entropy encoding unit encodes a moving image, the entropy encoding unit functions as a code amount calculation unit that estimates a required code amount. (3) The entropy encoding unit performs the estimation result of the code amount calculation device. (4) The code amount calculation means stores (4-1) an initial interval width at the start of processing related to the binary code string sequence. Initial section width Storing means, (4-2) section width holding means for setting the initial section width as an initial value, and holding a section width updated in accordance with the sequence of the binary code string, and (4-3) the binary value. A binary code string processing means for controlling state transition in accordance with a code string series and the context variable series; and (4-4) the binary code string processing means has bit-shifted the section width by normalization processing. A bit shift number counting means for counting the number of times, (4-5) a count value of the bit shift number counting means, a code amount corresponding to the initial interval width, and all 2 relating to the binary code string series And calculating means for calculating a code amount output from the entropy encoding means based on a code amount corresponding to the section width held by the section width holding means at the end of the processing of the value code string. .

  ADVANTAGE OF THE INVENTION According to this invention, the code amount at the time of encoding a moving image can be calculated | required efficiently.

It is the block diagram shown about the functional structure of the code amount calculation part which concerns on 1st Embodiment. It is the block diagram shown about the functional structure of the moving image encoder which concerns on 1st Embodiment. It is the block diagram shown about the functional structure of the entropy encoding part which concerns on 1st Embodiment. It is the flowchart shown about operation | movement of the code amount calculation part which concerns on 1st Embodiment. It is explanatory drawing shown about the structural example of the code amount table T used by the code amount calculation part which concerns on 1st Embodiment. It is the block diagram shown about the functional structure of the code amount calculation part which concerns on 2nd Embodiment. It is the flowchart shown about operation | movement of the code amount calculation part which concerns on 2nd Embodiment.

(A) First Embodiment A code amount calculation device and program, and a moving image encoding device and program according to a first embodiment of the present invention will be described in detail below with reference to the drawings. In the first embodiment, an example is shown in which the code amount calculation device of the present invention is configured as a code amount calculation unit that constitutes a moving image encoding device.

(A-1) Configuration of the First Embodiment FIG. 2 is a block diagram showing the overall configuration of the moving picture encoding apparatus 1 of this embodiment. In FIG. 2, the reference numerals in parentheses are used only in the second embodiment to be described later.

  The moving image encoding apparatus 1 includes a screen division unit 101, a space conversion unit 102, a quantization unit 103, an entropy encoding unit 104, an inverse quantization unit 105, an inverse space conversion unit 106, an in-loop filter unit 107, and a reference image buffer. 108, an inter prediction unit 109, an intra prediction unit 110, a coding mode selection unit 111, a code amount calculation unit 112, a prediction residual signal generation unit 113, and a decoded image generation unit 114.

  The moving picture coding apparatus 1 is a moving picture coding according to the embodiment to a computer having a processor, a memory, and the like (not limited to one, but may be configured so that a plurality of pieces can be distributedly processed). It may be constructed by installing a program (including the code amount calculation program of the embodiment) or the like, and even in that case, it can be functionally shown as in FIG. 2, the configuration other than the code amount calculation unit 112 is not limited. Since the same devices as those of various video encoding devices conforming to H.264 or the like can be applied, the description is omitted for details.

  The screen division unit 101 divides the target image (input image) into screens for each processing unit area such as a macroblock, and supplies the divided image to the prediction residual signal generation unit 113.

  The prediction residual signal generation unit 113 obtains a prediction residual signal from the divided image data supplied from the screen division unit 101 and the prediction image supplied from the inter prediction unit 109 or the intra prediction unit 110, and obtains a spatial This is supplied to the conversion unit 102.

  The spatial transform unit 102 spatially transforms the prediction residual signal by DCT (Discrete Cosine Transform) or its integer approximation transform to obtain transform coefficients. Then, the quantization unit 103 obtains a quantized prediction residual signal as a result of quantizing the transform coefficient with a predetermined quantization width, and supplies the quantized prediction residual signal to the entropy coding unit 104.

  Then, the entropy encoding unit 104 as the entropy encoding means performs entropy encoding (for example, arithmetic encoding) on the quantized prediction residual signal and encoding information such as mode information, and other codes. The encoded stream data is generated together with the encoding information. The data of this encoded stream becomes the output of the moving image encoding apparatus 1.

  The inverse quantization unit 105 inversely quantizes the quantized prediction residual signal. Then, the inverse spatial transform unit 106 performs inverse spatial transform (such as inverse orthogonal transform) on the result of inverse quantization of the prediction residual signal, obtains a prediction residual signal with a quantization error, and performs decoding. This is supplied to the image generation unit 114.

  The decoded image generation unit 114 obtains a decoded image from a prediction residual signal (input signal from the inverse spatial transform unit 106) accompanied with a quantization error and a prediction image (a prediction image from the inter prediction unit 109 or the intra prediction unit 110). . The decoded image generation unit 114 supplies the decoded image to the in-loop filter unit 107 and the intra prediction unit 110.

  The in-loop filter unit 107 functions as a deblocking filter or the like that reduces block distortion due to quantization for the decoded image. Then, the in-loop filter unit 107 supplies the filtered decoded image to the reference image buffer 108.

  The reference image buffer 108 holds the decoded image subjected to the filtering process from the in-loop filter unit 107 as a reference image for inter prediction motion compensation at the time of encoding the subsequent image. H. In the case of the H.264 / AVC standard, an image to be referred to in motion compensation is not limited to an image immediately before an image to be currently encoded, and images at a plurality of times can be reference images.

  The inter prediction unit 109 generates prediction image data by obtaining prediction information such as motion compensation from the target image data to be currently encoded and the reference image in the reference image buffer 108. The intra prediction unit 110 generates predicted image data using a decoded image that has already been encoded and locally decoded. In the moving image encoding apparatus 1, predicted image data using either the inter prediction unit 109 or the intra prediction unit 110 is converted into a prediction residual signal generation unit 113 and a decoded image in accordance with control of the encoding mode selection unit 111. It is supplied to the generation unit 114.

  The encoding mode selection unit 111 includes an encoding mode based on intra prediction (encoding based on a prediction image output from the intra prediction unit 110) and an encoding mode based on inter prediction (output from the inter prediction unit 109) for each target image. Or encoding based on the predicted image to be determined). In the moving image encoding apparatus 1 of this embodiment, although it demonstrates as what respond | corresponds to the above-mentioned two encoding modes, it does not limit about the number and kind of encoding mode which the moving image encoding apparatus 1 respond | corresponds. Is. Then, the coding mode selection unit 111 selects a coding mode that minimizes the RD cost by rate distortion optimization from a plurality of coding modes. At this time, the encoding mode selection unit 111 obtains the generated code amount R when encoding is performed in each encoding mode by the code amount calculation unit 112 and uses it for calculation of the RD cost.

  Next, the internal configuration of the entropy encoding unit 104 will be described with reference to FIG.

  In the entropy encoding unit 104 of this embodiment, entropy encoding using arithmetic codes such as CABAC is performed as entropy encoding.

  As shown in FIG. 3, the entropy encoding unit 104 of this embodiment includes a binarization unit 201, a context calculation unit 202, a context variable table 204, and an arithmetic encoding unit 203.

  In the entropy encoding unit 104, coefficient information, mode information, and the like, which are quantized prediction residual signals, are input from the quantization unit 103 as syntax elements.

  Then, the syntax element is converted by the binarization unit 201 into a sequence of binary code strings called bins. Then, the context calculation unit 202 obtains an index to the context variable table 204 that holds a state relating to the occurrence probability of the bin for each context according to the syntax element, surrounding encoded information, and the like.

  Then, the arithmetic encoding unit 203 performs arithmetic encoding according to the corresponding context variable for each bin generated by the binarizing unit 201, and outputs the result as an encoded bit stream.

  Next, the internal configuration of the code amount calculation unit 112 will be described with reference to FIG.

  As shown in FIG. 1, the code amount calculation unit 112 includes an initial interval width storage unit 301, an interval width holding unit 302, a bit number counter 303, a binary code string processing unit 304, and a code amount calculation unit 305. Yes.

  As shown in FIG. 1, the code amount calculation unit 112 outputs the same bin (binary code string) as that generated by the entropy encoding unit 104 to the syntax element of the encoding unit for estimating the code amount. ) And the context variable series corresponding to each bin are input.

  The initial section width storage unit 301 reads and stores section width information that is an internal state of the arithmetic coding unit 203 at the start of code amount estimation.

  The section width holding unit 302 holds the section width initialized by the initial section width and updated by the binary code string processing unit 304.

  The binary code string processing unit 304 controls state transition of the section width of the section width holding unit 302 in the same manner as when arithmetic coding is actually performed according to the input bin and the context variable. .

  The bit number counter 303 holds the number of times the section width is bit shifted by normalization.

When the binary code string of the encoding unit to be calculated is processed, the code amount calculation unit 305 determines the value held by the bit number counter 303 and the interval width at the end of the processing of the binary code string processing unit 304 The code amount corresponding to the initial section width is subtracted from the sum of the code amounts corresponding to, and output as the code amount to be encoded.
(A-2) Operation of the First Embodiment Next, the operation of the video encoding device 1 of the first embodiment having the above configuration will be described.

  As described above, in the video encoding device 1, the same processing as that of various video encoding devices can be applied to the processing other than the code amount calculation unit 112. The explanation is omitted.

  Hereinafter, a specific example of the operation in which the code amount calculation unit 112 calculates the code amount for the encoding unit of the target image to be calculated will be described.

  In the code amount calculation unit 112, when a binary code string of a coding unit for code amount calculation and a sequence of context variables corresponding to each bin are input, first, an initial interval width is stored in the initial interval width storage unit 301. Remember. The initial interval width is obtained by reading the internal state of the arithmetic coding unit 203 that performs the actual arithmetic coding, and the arithmetic encoder (entropy coding unit 104) obtained by performing the coding up to the target coding unit. ).

  At this time, the section width holding unit 302 is initialized with the initial section width. Further, the bit number counter 303 is also initialized to zero.

  Then, the binary code string processing unit 304 processes the state transition of the section width using the context variable corresponding to each bin of the input binary code string as in the case of actually performing arithmetic coding.

  FIG. 4 is a flowchart showing processing of each bin by the code amount calculation unit 112 (binary code string processing unit 304). The binary code string processing unit 304 executes the process of the flowchart of FIG. 4 for each bin (binVal).

  First, when a bin (binVal) and a context variable (pStateIdx, valMPS) are input, the binary code string processing unit 304 obtains a division width of the section width (codIRRange) held in the section width holding unit 302 ( S101).

  Since the section width is divided into sections for LPS (least probable symbol) and MPS (most probable symbol), the binary code string processing unit 304 obtains the divided section width ( codIRrangeLPS, codIRrangeMPS). That is, in step S101, section widths (codIRrangeLPS, CcodRangeMPS) for LPS and MPS obtained by dividing the section width (codrange) held in the section width holding unit 302 are obtained. In CABAC, codIRrangeLPS is obtained by table lookup using the upper bits of pStateIdx and codIRRange.

  Then, the binary code string processing unit 304 determines whether or not the bin (binVal) input this time is MPS (equal to valMPS) (S102). In step S102, the binary code string processing unit 304 operates from step S103 described later when the currently input bin is determined to be MPS, and will be described later if it is not determined to be MPS (if it is LPS). The operation starts from step S107.

  If it is determined in step S102 that the bin currently input is MPS, the binary code string processing unit 304 updates the section width of the section width holding unit 302 to the section width of MPS (codIRRange = codIRRangeMPS) ( Further, the context variable is updated (S104).

  Then, the binary code string processing unit 304 confirms whether or not the updated section width is smaller than 256 (hexadecimal “0x100”) (S105).

  The binary code string processing unit 304 requires normalization (bit shift) once when the updated section width is smaller than 256 (maximum once in the case of MPS). ), The value (bitCount) of the bit number counter 303 is incremented by 1 (bitCount = bitCount + 1), the section width is also shifted by 1 bit and normalized (codIRRange = codIRRange << 1) (S106), and the processing of the bin ends. . When it is confirmed that the section width updated in step S105 described above is 256 or more, the binary code string processing unit 304 ends the bin processing.

  On the other hand, if it is determined in step S102 that the bin (binVal) input this time is LPS, the binary code string processing unit 304 updates the section width of the section width holding unit 302 to the section width of the LPS (codIRRange). = CodlRangeLPS) (S107), and the context variable is updated (S108).

  Then, the binary code string processing unit 304 performs normalization processing by updating the bit number counter and the interval width until the interval width becomes 256 (hexadecimal “0x100”) or more (until the normalization processing is completed). The same bit shift processing as in step S106 described above is repeated, and the processing related to the bin ends (S109, S110).

  In the case of bypass coding (a bin with a probability of 1/2 assuming no context variable), the binary code string processing unit 304 is configured to simply increase the bit number counter by 1 (bitCount = bitCount + 1). Also good. When the bypass encoding bins are continuous, the binary code string processing unit 304 may be configured to add the bypass encoding bin number m to the bit number counter (bitCount = bitCount + m).

  The above processing of the flowchart of FIG. 4 is repeated for the input bin series and the context variable series corresponding to each bin, so that the section width of the section width holding unit 302 is actually subjected to arithmetic coding. The state transitions as in the case. As a result, the number of bits that will be output is held in the bit number counter 303.

  The code amount calculation unit 305 includes the value (bitCount) of the bit number counter 303 obtained by the above processing, the initial interval width (codIRRangeS) stored in the initial interval width storage unit 301, and the interval width after the target sequence processing. The code amount for the encoding target is calculated using the section width (codIRRange) of the holding unit 302.

  In CABAC, the interval width of an arithmetic code is expressed with 9-bit precision and is normalized so as to satisfy the following expression (1). That is, in CABAC, as the interval width of the arithmetic code is smaller, it corresponds to the fact that information of 1 bit or less is already generated as the code amount, and the code amount can be expressed as the following equation (2). In the expressions (1) and (2), “0x100” and “0x200” are expressed in hexadecimal numbers.

0 × 100 ≦ coIRRange <0x200 (1)
-Log ₂ (codIRRange / 0x200) (2)
Then, as shown in FIG. 5, the code amount corresponding to the section width can be realized, for example, as a table (hereinafter referred to as “code amount table T”) expressed by a fixed decimal having 16 bits after the decimal point.

  For example, when the code amount R is calculated as a fixed decimal with 16 bits after the decimal point, the code amount calculation unit 305 uses the following (a) (bitCount), “codIRRangeS and codIRRange”, and the above-described code amount table T ( 3) It can obtain | require by Formula. Then, the code amount calculation unit 305 outputs the obtained code amount R.

R = (bitCount << 16) + T [codIRrange-0 × 100]
-T [codIRRangeS-0 × 100] (3)
(A-3) Effects of First Embodiment According to the first embodiment, the following effects can be achieved.

  The code amount calculation unit 112 of the moving image encoding device 1 does not actually encode the code amount required by the arithmetic encoding of the entropy encoding unit 104 (without processing for obtaining the output bit pattern). It can be obtained with higher precision than integer precision.

  Specifically, since the encoding mode selection unit 111 performs the transition process of the section width of the arithmetic code similar to the case where the encoding is actually performed, it is not an approximation like the process by the table lookup of Patent Document 1. Code amount can be calculated. Furthermore, the encoding mode selection unit 111 can obtain a code amount with higher accuracy than integer accuracy from the section width of the initial state at the start of encoding and the state at the end. Thereby, in the moving image encoding device 1, the encoding mode selection unit 111 can select a more optimal encoding mode, and the encoding efficiency is improved.

(B) Second Embodiment Hereinafter, a second embodiment of a code amount calculation device and program, and a moving image coding device and program according to the present invention will be described in detail with reference to the drawings. In the second embodiment, an example is shown in which the code amount calculation device of the present invention is configured as a code amount calculation unit that constitutes a moving image encoding device.

(B-1) Configuration of Second Embodiment The overall configuration of the moving image encoding apparatus 1A of the second embodiment can also be shown using FIG.

  FIG. 6 is a block diagram illustrating a functional configuration of the code amount calculation unit 112A mounted in the moving image encoding apparatus 1A according to the second embodiment, and the same or corresponding parts as those in FIG. Are given the same or corresponding symbols.

  The code amount calculation unit 112A is different from the first embodiment in that a normalization count table 306 is added. The normalization count table 306 is a table that makes it possible to obtain the normalization count k corresponding to the section width of each bin.

  As described above, when the binary code string processing unit 304 performs processing on each bin, if the bin is LPS, it is necessary to perform normalization processing a plurality of times. The binary code string processing unit 304 of the first embodiment manages the number of times of normalization for LPS bins by loop processing (the processing of steps S109 and S110 described above). It manages using the normalization number table 306 which can acquire the normalization number k corresponding to every.

  That is, when processing each bin, if the bin is an LPS, the binary code string processing unit 304 acquires the normalization count k corresponding to the bin from the normalization count table 306. Then, the binary code string processing unit 304 executes normalization processing (the same processing as step S110 described above) for the acquired number of normalizations k.

  For LPS bins, the updated interval width depends only on codIrangeLPS. Therefore, the code amount calculation unit 112A can prepare the normalization count k necessary for each bin as the normalization count table 306 in advance based on the codIRRangeLPS.

  For example, in CABAC, it is possible to prepare a table limited according to the range that codIRangeLPS can take. Alternatively, the table for obtaining codIRangeLPS may be a table including the corresponding number of normalizations.

(B-2) Operation of Second Embodiment Next, the operation of the moving image coding apparatus 1A (code amount calculation unit 112A) of the second embodiment having the above-described configuration will be described in the first embodiment. The difference will be mainly explained.

  FIG. 7 is a flowchart showing processing of each bin by the code amount calculation unit 112A (binary code string processing unit 304) constituting the code amount calculation unit 112A. The binary code string processing unit 304 of the second embodiment executes the process of the flowchart of FIG. 7 for each bin (binVal).

  Since steps S201 to S208 shown in FIG. 7 are the same as steps S101 to S108 of the first embodiment, detailed description thereof will be omitted.

  Then, the code amount calculation unit 112A (binary code string processing unit 304) of the second embodiment performs loop processing (steps S109 and S110) as in the first embodiment when normalizing the LPS bins. Instead, a plurality of normalization processes are realized by a process using the normalization number table 306.

  Specifically, when the bin to be processed is determined to be LPS in step S202 described above, the binary code string processing unit 304 determines the normalization count k (codIRrangeLPS) corresponding to the bin from the normalization count table 306. The normalization count k) corresponding to is obtained from the normalization count table 306 (S209). Then, the binary code string processing unit 304 performs normalization processing (bit shift processing) for the number of times of normalization k for the section width held by the section width holding unit 302 (S210).

  Specifically, in step S210, the binary code string processing unit 304 increases the value of the bit number counter 303 by k bits according to the number of normalizations k (bitCount = bitCount + k), and the section width of the section width holding unit 302 is also increased. Shift by k bits and normalize (codIRrange = codIRrange << k).

  By repeating the above process for the input bin series and the context variable series corresponding to each bin, the code amount calculation unit 112A actually performs arithmetic coding on the section width of the section width holding unit 302. In the same way as in the case of the case, the number of bits to be output is obtained in the bit number counter 303.

  The code amount calculation unit 305 then obtains the value (bitCount) of the bit number counter 303 obtained by the above processing, the initial interval width (codIRRangeS) stored in the initial interval width storage unit 301, and the target sequence after processing The code amount R for the calculation target sequence is calculated and output using the section width (codrange) of the section width holding unit 302.

(B-3) Effects of Second Embodiment According to the second embodiment, the following effects can be obtained in addition to the effects of the first embodiment.

  In the code amount calculation unit 112 according to the second embodiment, the normalization process by the bit shift of the section width is not a loop process as in the first embodiment but a table lookup process, thereby enabling the first embodiment. As a result, it is possible to reduce the processing amount necessary for calculating the code amount.

(C) Other Embodiments The present invention is not limited to the above-described embodiments, and may include modified embodiments as exemplified below.

(C-1) In each of the above embodiments, the code amount calculation unit has been described as constituting a part of the moving image encoding device. However, the code amount calculation unit is constructed as an independent device (code amount calculation device). You may make it do. In that case, the functional configuration of the code amount calculation apparatus of the present invention can be shown as shown in FIG. Note that the code amount calculation apparatus according to the present invention is applied to a computer (not limited to one, but may be configured to be capable of distributed processing of a plurality of units) having a processor and a memory. It may be constructed by installing a quantity calculation program or the like, and even in that case, it can be functionally shown as in FIG.

(C-2) In the above embodiment, the moving picture coding apparatus according to the present invention is an H.264 format. Although an example using entropy coding (CABAC) based on H.264 has been described, video coding processing corresponding to various other coding using arithmetic coding may be applied.

  DESCRIPTION OF SYMBOLS 1 ... Moving image encoder 11 ... Screen division part, 102 ... Spatial transformation part, 103 ... Quantization part, 104 ... Entropy coding part, 105 ... Inverse quantization part, 106 ... Inverse space transformation part, 107 ... In a loop Filter unit 108 Reference image buffer 109 Inter prediction unit 110 Intra prediction unit 111 Coding mode selection unit 112 Code amount calculation unit 113 Prediction residual signal generation unit 114 Decoded image generation , 201 ... binarization unit, 202 ... context calculation unit, 203 ... arithmetic coding unit, 204 ... context variable table, 301 ... initial interval width storage unit, 302 ... interval width holding unit, 303 ... bit number counter, 304 ... Binary code string processing unit, 305 ... Code amount calculation unit.

Claims (6)

A sequence of binary code sequences related to encoded information such as a residual signal and prediction information of a target image constituting a moving image and a predicted image of the target image, and a binary code sequence related to the encoded information When the moving image is encoded using the entropy encoding unit that performs entropy encoding of the encoding information based on the context variable sequence representing the probability state, the entropy encoding unit outputs the encoded moving image. In the code amount calculation device for calculating the code amount of the code,
Initial interval width storage means for storing an initial interval width at the start of processing related to the binary code string sequence;
Section width holding means for setting the initial section width as an initial value and holding a section width updated according to the sequence of the binary code string;
Binary code string processing means for controlling the state transition of the section width of the section width holding means in accordance with the binary code string series and the context variable series;
The binary code string processing means counts the number of times the section width is bit-shifted by normalization processing;
The count value of the bit shift number counting means, the code amount corresponding to the initial interval width, and the interval held by the interval width holding means at the end of processing of all binary code strings related to the binary code string sequence A code amount calculation apparatus comprising: a calculation unit that calculates a code amount output from the entropy encoding unit based on a code amount corresponding to a width. A normalization number information holding means for holding information capable of acquiring a normalization number corresponding to each interval width related to the binary code string;
The binary code string processing means performs a normalization process by a bit shift for the number of times based on information held in the normalization number information holding means for each interval width related to the binary code string,
The bit shift number counting means adds the number of times based on the information held in the normalized number holding means to the counter value for each section width related to the binary code string. The code amount calculation device described in 1.   The binary code string processing means performs only the process of adding the counter value of the bit shift number counting means for the binary code string to be bypass-coded among the binary code string series. The code amount calculation apparatus according to claim 2. Probability states of a binary code string related to encoded information such as a residual signal and prediction information of a target image constituting the moving image and a predicted image of the target image, and a binary code string related to the encoded information The entropy coding means for performing entropy coding of the coding information based on the context variable sequence representing the coding information, and the amount of code required when the moving image is coded by the entropy coding means, A moving picture coding apparatus that outputs a code related to coding information selected based on an estimation result of the coding quantity calculation apparatus.
4. A moving picture coding apparatus, wherein the code quantity calculation apparatus according to claim 1 is applied as the code quantity calculation means. Probability states of a binary code string related to encoded information such as a residual signal and prediction information of a target image constituting the moving image and a predicted image of the target image, and a binary code string related to the encoded information When encoding the moving image using the entropy encoding unit that performs entropy encoding of the encoding information based on the context variable sequence that represents the code of the code output by the entropy encoding unit In the code amount calculation program for calculating the code amount,
Computer
Initial interval width storage means for storing an initial interval width at the start of processing related to the binary code string sequence;
Section width holding means for setting the initial section width as an initial value and holding a section width updated according to the sequence of the binary code string;
Binary code string processing means for controlling the state transition of the section width of the section width holding means in accordance with the binary code string series and the context variable series;
The binary code string processing means counts the number of times the section width is bit-shifted by normalization processing;
The count value of the bit shift number counting means, the code amount corresponding to the initial interval width, and the interval held by the interval width holding means at the end of processing of all binary code strings related to the binary code string sequence A code amount calculation program that functions as a calculation unit that calculates a code amount output from the entropy encoding unit based on a code amount corresponding to a width. Computer
Probability states of a binary code string related to encoded information such as a residual signal and prediction information of a target image constituting the moving image and a predicted image of the target image, and a binary code string related to the encoded information Entropy encoding means for performing entropy encoding of the encoded information based on a sequence of context variables representing
When encoding the moving image with the entropy encoding unit, the entropy encoding unit functions as a code amount calculation unit that estimates a required code amount,
The entropy encoding means outputs a code related to encoding information selected based on the estimation result of the code amount calculation device,
The code amount calculation means includes:
Initial interval width storage means for storing an initial interval width at the start of processing related to the binary code string sequence;
Section width holding means for setting the initial section width as an initial value and holding a section width updated according to the sequence of the binary code string;
Binary code string processing means for controlling state transition of the section width of the section width holding means in accordance with the binary code string series and the context variable series;
The binary code string processing means counts the number of times the section width is bit-shifted by normalization processing;
The count value of the bit shift number counting means, the code amount corresponding to the initial interval width, and the interval held by the interval width holding means at the end of processing of all binary code strings related to the binary code string sequence A moving picture encoding program comprising: a calculation unit that calculates a code amount output from the entropy encoding unit based on a code amount corresponding to a width.

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