KR100674937B1 - Context adaptive binary arithmetic de-coding device - Google Patents

Abstract

Disclosed is a context-adaptive binary arithmetic decoding apparatus capable of simultaneously decoding a plurality of bits without using a complicated context modeling process when reconstructing image data, which can be processed more quickly and simply. The context adaptive binary arithmetic decoding apparatus includes a memory device, a peripheral macroblock information device, a context index generator, a context updater, a context selector, a decoding engine block, and an inverse discretization block. The context-adaptive binary arithmetic decoding apparatus has an advantage of faster and simpler decoding using a context index generator and a context update apparatus.

Description

Context adaptive binary arithmetic de-coding device

BRIEF DESCRIPTION OF THE DRAWINGS In order to better understand the drawings cited in the detailed description of the invention, a brief description of each drawing is provided.

1 is a block diagram of a CABAC device according to the H.264 standard.

FIG. 2 is a block diagram of a CABAD device corresponding to the CABAC device shown in FIG. 1.

3 is a block diagram of a context-adaptive binary arithmetic decoding apparatus according to an embodiment of the present invention.

4 shows the structure of memory and registers for context initialization and update.

5 shows a context register group.

6 shows a relationship between a neighboring macroblock and a current macroblock.

7 shows information to be stored per neighboring macroblock used in the present invention and a map of a memory device storing the same.

8 is an example of a memory map in the case of an H.264 main file having a total video size of 1920 × 1088.

The present invention relates to the compression of moving image data, and more particularly, to a context-adaptive binary arithmetic decoding apparatus that can be processed more quickly and simply.

Since video data has a large amount of data, it is generally compressed and then stored or transmitted. There are various ways of compressing data, but they must meet certain standards, such as MPEG-4 Part 10 Advanced Video Coding (AVC) or ITU-T H.264. H.264 was established to cope with the rapid dissemination of new concept communication channels such as mobile communication networks, and is for various communication infrastructures (Infra) which are switched from the conventional circuit switched method to packet switched service.

H.264 has increased coding efficiency by more than 50% compared to the MPEG-4 Part 2 Visual Codec, which is a conventional standard. It is easy to adapt to a network with less errors in consideration of the rapidly changing wireless environment and the Internet environment. It is a video data compression standard considering the method.

Most of the conventional video compression standards developed using Huffman Lossless Coding, and only recently introduced Arithmetic Coding, which has a higher compression efficiency, have been introduced in H.264. Context Adaptive Binary Arithmetic Coding (CABAC) is introduced. The CABAC is an entropy encoding method for compressing data by using a probability of occurrence of a symbol.

General arithmetic coding uses alphabet based sources, but CABAC uses context based sources differently. The CABAC defines a context and each context is modeled based on the neighboring block or previously encoded value.

CABAC encodes a binary string consisting of '0's and' 1's called bins. The binary string is converted into an integer in the process of being processed, and thus a process of converting data consisting of integers into binary codes is required. The binary conversion process depends on the syntax.

CABAC uses a QM-Coder designed by IBM to encode a binary string. The QM-Coder does not have a multiplication operation, but only a shift, addition and subtraction operation of data. It has the advantage of being easy and fast. It also has its own modeling technique suitable for binary coding.

1 is a block diagram of a CABAC device according to the H.264 standard.

Referring to FIG. 1, the CABAC device 100 may include a binarization block 110, a syntax block 120, a context block 130, a QM-Coder 140, a model block 150, and a model update block 160. ).

The binarization block 110 binarizes the received value of the encoding corresponding to the syntax 120. The binarized binary string is transmitted to the QM-Coder 140 and encoded into a bit stream composed of a plurality of bit strings.

The QM-Coder 140 determines the probability and state of each binary symbol through its own modeling process using the context received from the context block 130. The context block 130 receives the information about the syntax and the information about the set model from the syntax block 120 and the model block 150, and selects a context for each syntax and binary position based on an already encoded block.

When one slice is made into a bit stream through the operation of the above-described blocks, the context model is updated in the model update block 160 using the bit stream and transferred to the model block 150.

FIG. 2 is a block diagram of a CABAD device corresponding to the CABAC device shown in FIG. 1.

2, the context adaptive binary arithmetic de-coding (CABAD) device 200 can be found to perform an inverse process of CABAC.

When the CABAD device 200 receives the information on the bit stream and the model from the CABAC device 100, the CABAD device 200 selects a context from the context block 220 according to the instruction of the syntax block 230 based on the information, and for each context. Decoded via the QM-Coder (210). The decoded string is mapped to the actual value through the inverse binarization process in the inverse binarization block 240 according to the instruction of the syntax block 230.

In the context-adaptive binary arithmetic decoding according to the conventional technique described above, the context modeling process performed by the context modeling unit is very complicated, and each bit is decoded one by one.

An object of the present invention is to provide a context adaptive binary arithmetic decoding apparatus capable of simultaneously decoding a plurality of bits without using a complicated context modeling process when restoring image data. To provide.

The CABAD according to the present invention for achieving the above technical problem, a memory device, a peripheral macroblock information device, a context index generator, a context update device, a context selector, a decoding engine block and a debinarization block.

The memory device stores information about syntax elements and contexts of macroblocks located in the vicinity of a macroblock currently being processed.

The peripheral macroblock information apparatus reads and stores the syntax element stored in the memory device, and includes a plurality of registers for this purpose.

The context index generator generates a context index increment for context selection by using a syntax element received from the neighboring macroblock information apparatus.

The context updating apparatus initializes a context stored therein or reads and stores a context to be currently used from the memory device, and stores a context in use in the memory device, and includes a plurality of registers for this purpose.

The context selector selects a predetermined context from among bin-specific contexts of syntax elements stored in the context updater in response to the context index increment.

The decoding engine block decodes the input data stream in word units using the context selected by the context selector.

The inverse binarization block outputs symbols corresponding to the decoded data by referring to a variable field coding table that is already stored.

The context adaptive binary arithmetic decoding apparatus may further include a controller. The controller controls the context index generator, the context selector, and the inverse binarization block. In addition, when an initialization condition is applied, the context updater and the decoding engine are initialized, and a variable field coding table is provided.

DETAILED DESCRIPTION In order to fully understand the present invention, the operational advantages of the present invention, and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings that illustrate preferred embodiments of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals in the drawings denote like elements.

3 is a block diagram of a context-adaptive binary arithmetic decoding apparatus according to an embodiment of the present invention.

Referring to FIG. 3, the context-adaptive binary arithmetic decoding apparatus 300 includes a memory device 310, a peripheral macroblock information device 320, a context index generator 330, a context updater 340, and a context. A selector 350, decoding engine block 360, and inverse discretization block 370 are provided.

The memory device 310 stores information about syntax elements and contexts of macroblocks located around the macroblock currently being processed.

The peripheral macroblock information device 320 reads and stores the syntax element stored in the memory device 310, and includes a plurality of registers for this purpose.

The context index generator 330 generates a context index increment for context selection by using a syntax element received from the neighboring macroblock information apparatus 320.

The context updating apparatus 340 initializes a context stored in itself or reads and stores a context that should be currently used from the memory device, and stores the used context in the memory device, and includes a plurality of registers for this purpose.

The context selector 350 selects a certain context from among bin-specific contexts of syntax elements stored in the context updater in response to the context index increment.

The decoding engine block 360 decodes the input data stream in units of bytes by using the context selected by the context selector 350.

The inverse binarization block 370 outputs the symbols corresponding to the decoded data by referring to a variable field coding table that is already stored.

The context-adaptive binary arithmetic decoding apparatus 300 may further include a controller 380.

The controller 380 controls the context index generator 330, the context selector 350, and the inverse binarization block 370. In addition, when the initialization condition is applied, the context update apparatus 340 and the decoding engine 360 are initialized, and a variable field coding table is provided.

The decoding process of the context adaptive binary arithmetic de-coding (CABAD) device according to an embodiment of the present invention shown in FIG. 3 will be briefly summarized.

First, when the initialization condition is applied to the controller 380, the context and the decoding engine are initialized, and when the decoding condition is applied, decoding of one macro block is performed. Prior to performing decoding, the neighboring macroblock information device 320 reads information of the neighboring macroblock, especially the syntax element of the neighboring macroblock, from the memory device 310. At the same time, the context update apparatus 340 reads the context from the memory device 310. Then, a context index increment (Context Index Increment) that can be calculated in the context index generator 330, the syntax element to be decoded is generated at this time. The context selector 350 selects a context corresponding to the bin number of the syntax element.

The received data stream is decoded in bytes using a context corresponding to the bin number of the syntax element. Then, while checking the decoded empty values, we generate syntax elements and coefficients. At this point, the changed context must be updated and stored in memory.

Hereinafter, operations of important parts of context adaptive binary arithmetic decoding (CABAD) according to an embodiment of the present invention shown in FIG. 3 will be described in more detail.

1. Context updating device 340

When an initialization condition is applied, two sets of eight 7-bit registers are used as one set to initialize the context alternately between calculations and operations.

When the context update condition is applied, the currently used context is read from the memory device 310 and stored, and the previously used context is stored in the memory device 310.

4 shows the structure of memory and registers for context initialization and update.

4, there are seven register sets on the left and a 56x70 memory area on the right. Each block of the memory area is called a context, and the bits constituting each context are collectively called a syntax element.

5 shows a context register group.

Referring to FIG. 5, the context reads data in groups. After reading, rewrite the previously updated context. The number of contexts refers to the number of contexts and also the number of registers to be filled. Register File means a register set.

2. Peripheral macroblock information device 320

CABAD sometimes uses information of neighboring macroblocks when decoding. For this purpose, the CABAD receives an address of a neighboring block from a main controller (not shown) and calculates an actual memory address.

6 shows a relationship between a neighboring macroblock and a current macroblock.

Referring to FIG. 6, neighboring blocks A and B are around a current block Current.

7 shows information to be stored per neighboring macroblock used in the present invention and a map of a memory device storing the same.

Referring to FIG. 7, the map of the memory to be stored per peripheral macroblock of the memory device used in the present invention is 32x7. In the case of the MBAFF (Macro Block Adaptive Field / Frame) mode, information about the neighboring macroblocks is assumed to require macroblock information of up to two lines of the entire image size.

8 is an example of a memory map in the case of an H.264 main file having a total video size of 1920 × 1088.

Referring to FIG. 8, in the case of MBAFF, it is preferable to form a map to form a pair up and down.

If it is not in MBAFF mode, it is not necessary to display in pairs. The increase in physical memory address increases equally regardless of the MBAFF mode.

Always store the physical address of the current macro block, and then calculate the physical address of the surrounding macro block. The physical address of the current macro block is increased by the size offset of the macro block. Given the number of neighboring macroblocks, we can calculate the difference from the number of the current macroblock and multiply it by the offset to get the actual address of the neighboring macroblock. Once the address is obtained, 32 bits are read and stored in the register.

When decoding of one macro block is completed, it is stored.

As described above, the optimum embodiment has been disclosed in the drawings and the specification. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not intended to limit the scope of the invention as defined in the claims or the claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, the Context Adaptive Binary Arithmetic De-coding apparatus according to the present invention has the advantage of being able to decode a plurality of bits simultaneously at the same time as compared with the conventional apparatus when restoring image data. There is this.

Claims (7)

A memory device which stores information on syntax elements and contexts of macroblocks located around the macroblock currently being processed; A peripheral macroblock information device for reading and storing the syntax element stored in the memory device; A context index generator for generating a context index increment for context selection using the syntax element of the neighboring macroblock; A context updater configured to initialize the context or read a context to be currently used from the memory device using information around the macroblock, and store the used context in the memory device; A context selection device for selecting a context corresponding to a bin number of the syntax element from among contexts stored in the context updating apparatus in response to the context index increment; A decoding engine block for decoding the input data stream using the context selected by the context selector; And And an inverse discretization block for outputting symbols corresponding to the decoded data by referring to a variable field coding table which is already stored. Context Adaptive Binary Arithmetic De-coding (CABAD). The apparatus of claim 1, wherein the peripheral macroblock information apparatus comprises: And a plurality of registers for storing the syntax element. The apparatus of claim 1, wherein the context updating apparatus comprises: And a plurality of registers for storing the selected context. The method of claim 1, wherein the decoding engine block, CABAD device characterized in that decoding on a byte basis. According to claim 1, The CABAD device, And a controller block for controlling the context index generator, the context selector, and the inverse discretization block. The method of claim 5, wherein the controller, And a initialization condition is applied, wherein the context updating device and the decoding engine are initialized. The method of claim 5, wherein the controller, And a variable field coding table.

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