KR100358159B1 - Method for selecting macroblock compression mode in video coding system - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method for selecting a macroblock compression mode in an image compression system and a computer-readable recording medium having recorded thereon a program for realizing the method.

2. The technical problem to be solved by the invention

The present invention implements a method and method for selecting a macroblock compression mode for selecting in consideration of not only the compression efficiency but also the tolerance (error) for error in selecting the compression mode of each macroblock (MB) in an image compression system. To provide a computer-readable recording medium that records a program for the purpose.

3. Summary of Solution to Invention

According to an aspect of the present invention, there is provided a method of selecting a compression mode of a macroblock in which an image frame is divided in a video compression system, the method comprising: setting a first parameter (A) in consideration of an influence of error tolerance (stiffness); A second step of comparing the first parameter A with a second parameter T considering compression efficiency and error tolerance at the same time; A third step of compressing the macroblock into an intra mode when the first parameter A is larger than the second parameter T according to the comparison result of the second step; And according to the comparison result of the second step, when the first parameter A is not larger than the second parameter T, the first number of bits B1 required for compression in the inter mode and the second After calculating one error value E1, the number of second bits B2 necessary for compression in the intra mode, and the second error value E2 at that time, the first parameter A is taken into consideration and the Including a fourth step of selecting a compression mode.

4. Important uses of the invention

The present invention is used in image compression systems and the like.

Description

Method for selecting macroblock compression mode in video coding system

The present invention relates to a method for selecting a macroblock (MB: MacroBlock) compression mode in an image compression system and a computer-readable recording medium recording a program for realizing the method. More specifically, the compression mode of each macroblock is described. In the selection, not only the compression efficiency but also the tolerance against the error (toughness) are considered.

Currently, in a system for transmitting and receiving video and sound, a video signal and audio signal are encoded and transmitted as a digital signal, stored in a storage unit, and decoded and reproduced. The methods used for encoding the video signals include a transform coding method, a differential pulse code modulation (DPCM) method, a vector quantization method, and a variable length coding (VLC) method. These coding schemes are used to compress the total amount of data by removing redundancy data included in the digital video signal. In order to perform such an encoding method, a screen is divided into blocks having a predetermined size, and a predetermined transformation is performed on each block or a difference signal between blocks to convert image data into a transform coefficient of a frequency domain.

Examples of data transformation methods for each block include a discrete cosine transform (DCT), a Walsh-Hadamard transform (WHT), a discrete fourier transform (DFT), and a discrete sine transform (DST). The transmission data is compressed by appropriately encoding such transform coefficients according to data characteristics. In order to restore the encoded and transmitted video data to the original video signal, it is necessary to transmit the head data including the encoded state information of the video signal together with the transmission of the video data.

In general, in the variable-length coding scheme of a moving picture, an intra mode is used when there is a large change between pictures, and an intermode is used when there is little change between pictures. Information is also included in the overhead data.

1 is a diagram illustrating a configuration of a general video compression system and illustrates an example of an inter / intra mode encoding apparatus.

In FIG. 1, image data VS is input to an N × N converter 11 through a first adder A1, and an output terminal of the N × N converter 11 is connected to an input terminal of the quantization unit 12. The output terminal of the quantizer 12 is connected to the variable length encoder 13. On the other hand, the image data VS is also supplied to the mode determination unit 20, so that the mode determination unit 20 determines the inter mode or the intra mode according to the degree of change of the image, so as to obtain the inter-mode / intra-mode information in the next bit. Supply to the map converter 21 and the two switches (RSW1, RSW2).

The output terminal of the bitmap converter 21 is connected to a run_length encoder 22, and the output of the run length encoder 22 is supplied to the variable length encoder 23 so that the variable length coded mode information is stored in a buffer ( 14) is applied. In this case, the variable length coded signal is transmitted after being delayed in the buffer 14, and a signal for determining the quantization level QS according to the buffer 14 state is supplied to the quantization unit 12 and the inverse quantization unit 15. do.

Meanwhile, the quantization unit 12 outputs the quantized signal to the inverse quantization unit 15, and the inverse quantization unit 15 is connected to an input terminal of the N × N inverse transform unit 16. At this time, the signal output from the N × N inverse transform unit 16 is applied to the frame memory 17 through the second adder A2, and the frame memory 17 is supplied to the equalizer 18 and the compensator 19. It is configured to apply each output. The output of the dynamic compensator 19 is applied to the first adder A1 and the second adder A2, respectively, and the dynamic compensator 18 receives the image data VS and receives the dynamic vector MV from the dynamic compensator 19. ) And is transmitted together with the encoded video signal VC.

Referring to the operation of the inter / intra-mode encoding device having the above configuration, the image data VS of the N × N block (generally, N1 × N2 block) includes the mode determiner 20 and the first adder A1. ) And the winter weight 18. At this time, the mode determining unit 20 encodes each mode in an inter mode when there are many similar parts between the telephone image and the current image, and an intra mode when there is a large change between the telephone image and the current image. Determine how. The inter mode / intra mode determined in this manner determines the inter mode / intra mode of the encoding apparatus by controlling the two switches RSW1 and RSW2.

However, in most image compression systems, each frame is divided into macroblocks having a predetermined size (generally, 16 × 16 size), and then each macroblock is compressed in an intra mode or an inter mode method. In this case, a block compressed in the inter mode predicts a block to be currently compressed from information in a previous frame and compresses only the prediction difference. However, when there is a lot of motion, the intra mode that compresses the current block without prediction is more efficient than the compression method through such prediction. This choice of intra / inter mode affects not only the compression efficiency but also the error robustness. In other words, the block compressed in the inter mode is also affected by the error generated in the previous frame, thereby reducing the tolerance (error) to the error.

Nevertheless, in the conventional video compression system, only the compression efficiency is considered, and the compression mode of each macroblock is selected without any consideration of the tolerance (error).

Therefore, in selecting the compression mode of each macroblock, it is necessary to consider not only the compression efficiency but also the tolerance against the error (toughness), so as to improve the image quality in a wireless communication environment where errors frequently occur. .

In order to solve the problems described above, the present invention provides a macro for selecting not only the compression efficiency but also the tolerance against errors (toughness) in selecting a compression mode of each macroblock (MB) in an image compression system. It is an object of the present invention to provide a method for selecting a compression mode of a block and a computer-readable recording medium having recorded thereon a program for realizing the method.

1 is an exemplary configuration diagram of a general video compression system.

2 is a flowchart illustrating an embodiment of a method for selecting a macroblock compression mode according to the present invention.

* Explanation of symbols for the main parts of the drawings

20: mode determination unit 21: bitmap conversion unit

22 run length encoder 23 variable length encoder (VLC)

In order to achieve the above object, the present invention provides a method for selecting a compression mode of a macroblock in which an image frame is divided in an image compression system, wherein the first parameter A is set in consideration of the influence of error tolerance (stiffness). First step; A second step of comparing the first parameter A with a second parameter T considering compression efficiency and error tolerance at the same time; A third step of compressing the macroblock into an intra mode when the first parameter A is larger than the second parameter T according to the comparison result of the second step; And when the first parameter A is not larger than the second parameter T according to the comparison result of the second step, the first number of bits B1 required for compression in the inter mode and the second After calculating one error value E1, the number of second bits B2 necessary for compression in the intra mode, and the second error value E2 at that time, the first parameter A is taken into consideration to determine the And a fourth step of selecting a compression mode.

In addition, the present invention provides a method of selecting a compression mode of a macroblock in which each image frame is divided in an image compression system, comprising: a first step of setting a first parameter (A) in consideration of an effect of error tolerance (stiffness); A second step of comparing the first parameter A with a second parameter T considering compression efficiency and error tolerance at the same time; A third step of compressing the macroblock into an intra mode when the first parameter A is larger than the second parameter T according to the comparison result of the second step; And a fourth step of compressing the macroblock into an inter mode when the first parameter A is not larger than the second parameter T according to the comparison result of the second step. It is done.

In order to achieve the above object, the present invention provides a first parameter (A) considering the effect of error tolerance (ruggedness) on an image compression system having a processor in order to select a compression mode of a macroblock in which each image frame is divided. A first function of setting a; A second function of comparing the first parameter A with a second parameter T considering compression efficiency and error tolerance at the same time; A third function of compressing the macroblock into an intra mode when the first parameter A is larger than the second parameter T according to a comparison result of the second function; And when the first parameter A is not larger than the second parameter T, according to a result of the comparison of the second function, the first number of bits B1 required for compression in the inter mode and the first number of times. After calculating one error value E1, the number of second bits B2 necessary for compression in the intra mode, and the second error value E2 at that time, the first parameter A is taken into consideration to determine the A computer readable recording medium having recorded thereon a program for realizing a fourth function of selecting a compression mode is provided.

In addition, the present invention provides a first function of setting a first parameter (A) in consideration of the effect of error tolerance (ruggedness) in an image compression system having a processor, in order to select a compression mode of a macroblock in which an image frame is divided. ; A second function of comparing the first parameter A with a second parameter T considering compression efficiency and error tolerance at the same time; A third function of compressing the macroblock into an intra mode when the first parameter A is larger than the second parameter T according to a comparison result of the second function; And according to a comparison result of the second function, when the first parameter A is not greater than the second parameter T, a program for realizing a fourth function of compressing the macroblock into an inter mode. Provide a computer-readable recording medium for recording.

Unlike the conventional method of compressing only the compression efficiency, the present invention selects the compression mode of each macroblock, so that errors are frequently generated by considering not only the compression efficiency but also the tolerance against the error (toughness). The image quality can be improved in a wireless communication environment.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention is to select whether to encode in the inter mode or intra mode for each block or macro block by receiving the image data, it can be applied to any image compression system that compresses in inter mode / intra mode. Self-explanatory

2 is a flowchart illustrating a method of selecting a macroblock compression mode according to the present invention.

As shown in FIG. 2, in the method of selecting a compression mode of a macroblock according to the present invention, an error tolerance influence parameter (A) is first defined to consider the effect of error tolerance in each macroblock in which each frame is divided into a predetermined size. (201). In this case, the A value changes depending on how many frames in the same position the macroblock is compressed in the intra mode. For example, if the current frame is the i-th frame and the last block of the current position in the j-th frame is compressed in the intra mode, it may be defined as "A = (i-j) * (i-j)".

Then, it is checked whether the value of the parameter A is greater than a predefined value, T (generally 10 to 400, preferably 100) (202). In this case, the predefined T value increases the T value when considering a lot of compression efficiency, and decreases the T value when considering a lot of error tolerance.

As a result of the check, if the parameter A is larger than the T value, the current macroblock is compressed in the intra mode (203).

As a result of the inspection, if the parameter A is not larger than the T value, the number of bits B1 necessary for the compression in the inter mode, the error value E1 at that time, and the number of bits B2 necessary for the compression in the intra mode, and the After calculating the error value E2 (204), the compression mode of the current macroblock is determined by considering the A value calculated in advance ((E1 + b × B1 + c × A)> (E2 + b × B2)) ( 205). That is, if (E1 + b × B1 + c × A) is greater than (E2 + b × B2), the current macroblock is compressed in intra mode (203), otherwise it is compressed in inter mode (206).

Here, b represents the number of bits weight, c represents the error tolerance weight, and the values of b and c are determined experimentally (generally, 20 to 400), and can be changed to any value. In particular, the value of c may vary depending on the channel environment to which the video service is to be applied. For example, it is effective to decrease the value of c in a wired environment or a retransmission environment, and to increase the value of c in a wireless communication environment where errors frequently occur.

The A value can also be determined in other ways than those defined above. For example, when an intra frame is periodically inserted, the value may be determined according to the number of frames after which the intra frame is inserted. That is, when the intra frame is inserted every 10 frames, if the seventh frame is an intra frame, the A value is 1 because one A frame is one.

The method of the present invention as described above may be implemented as a program and stored in a computer-readable recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.).

The present invention described above is capable of various substitutions, modifications, and changes without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains, and the above-described embodiments and accompanying It is not limited to the drawing.

As described above, the present invention can improve image quality in a wireless communication environment in which errors frequently occur by selecting not only the compression efficiency but also the tolerance against errors in selecting the compression mode of each macroblock during video compression. It works.

Claims (12)

In the video compression system, a method for selecting a compression mode of a macroblock in which each video frame is divided, A first step of setting a first parameter A in consideration of the influence of error tolerance (toughness); A second step of comparing the first parameter A with a second parameter T considering compression efficiency and error tolerance at the same time; A third step of compressing the macroblock into an intra mode when the first parameter A is larger than the second parameter T according to the comparison result of the second step; And According to the comparison result of the second step, when the first parameter (A) is not larger than the second parameter (T), the first number of bits (B1) required for compression in the inter mode and the first time at that time After calculating the error value E1, the number of second bits B2 necessary for the compression in the intra mode, and the second error value E2 at that time, the macroblock is compressed in consideration of the first parameter A. Fourth Step to Choose a Mode Macroblock compression mode selection method in an image compression system comprising a. The method of claim 1, The fourth step, According to the comparison result of the second step, when the first parameter is not larger than the second parameter, the first number of bits B1 and the first error value E1 required for compression in the inter mode A fifth step of obtaining a second number of bits B2 and a second error value E2 at the time of compression in intra mode; Determining a compression mode of the macroblock by the following equation; And According to the determination result of the sixth step, if (E1 + b × B1 + c × A) is greater than (E2 + b × B2), the seventh step of compressing the macroblock in intra mode, otherwise compressing in inter mode step Macroblock compression mode selection method in an image compression system comprising a. (E1 + b × B1 + c × A)> (E2 + b × B2)) (Where b is the bit weight and c is the error tolerance weight) The method of claim 2, B, c is, It is determined experimentally (generally, 20 to 400), and the value of c may be different depending on the channel environment to which the video service is to be applied. Preferably, the value of c in a wired environment or an environment capable of retransmission. A method of selecting a macroblock compression mode in a video compression system, characterized by increasing the value of c in a wireless communication environment in which errors are small and errors frequently occur. The method according to any one of claims 1 to 3, The first parameter (A), The macroblock at the same position changes depending on how many frames have been compressed into the intra mode. Preferably, if the current frame is the i-th frame and the last block of the current position at the j-th frame is compressed to the intra mode, Macroblock compression mode selection method in an image compression system, characterized in that defined by the equation. A = (i-j) * (i-j) The method according to any one of claims 1 to 3, The second parameter (T), Preferably it is 100, but if you want to consider a lot of compression efficiency to increase the second parameter (T), if you want to consider a lot of error tolerance is a variable value that can reduce the second parameter (T) Macroblock compression mode selection method in the image compression system, characterized in that. In the video compression system, a method for selecting a compression mode of a macroblock in which each video frame is divided, A first step of setting a first parameter A in consideration of the influence of error tolerance (toughness); A second step of comparing the first parameter A with a second parameter T considering compression efficiency and error tolerance at the same time; A third step of compressing the macroblock into an intra mode when the first parameter A is larger than the second parameter T according to the comparison result of the second step; And A fourth step of compressing the macroblock in an inter mode when the first parameter A is not larger than the second parameter T according to the comparison result of the second step. Macroblock compression mode selection method in an image compression system comprising a. The method of claim 6, The fourth step, According to the comparison result of the second step, when the first parameter (A) is not larger than the second parameter (T), the macroblock is compressed in inter mode, According to the comparison result of the second step, when the first parameter is not larger than the second parameter, the first number of bits B1 and the first error value E1 at the time of compression in the inter mode and A fifth step of obtaining a second number of bits B2 and a second error value E2 at the time of compression in intra mode; Determining a compression mode of the macroblock by the following equation; And According to the determination result of the sixth step, if (E1 + b × B1 + c × A) is greater than (E2 + b × B2), the seventh step of compressing the macroblock in intra mode, otherwise compressing in inter mode step Macroblock compression mode selection method in an image compression system comprising a. (E1 + b × B1 + c × A)> (E2 + b × B2)) (Where b is the bit weight and c is the error tolerance weight) The method of claim 7, wherein B, c is, It is determined experimentally (generally, 20 to 400), and the value of c may be different depending on the channel environment to which the video service is to be applied. Preferably, the value of c in a wired environment or an environment capable of retransmission. A method of selecting a macroblock compression mode in a video compression system, characterized by increasing the value of c in a wireless communication environment in which errors are small and errors frequently occur. The method according to any one of claims 6 to 8, The first parameter (A), The macroblock at the same position changes depending on how many frames have been compressed into the intra mode. Preferably, if the current frame is the i-th frame and the last block of the current position at the j-th frame is compressed to the intra mode, Macroblock compression mode selection method in an image compression system, characterized in that defined by the equation. A = (i-j) * (i-j) The method according to any one of claims 6 to 8, The second parameter (T), Preferably it is 100, but if you want to consider a lot of compression efficiency to increase the second parameter (T), if you want to consider a lot of error tolerance is a variable value that can reduce the second parameter (T) Macroblock compression mode selection method in the image compression system, characterized in that. In an image compression system having a processor, to select a compression mode of a macroblock in which each image frame is divided, A first function of setting a first parameter A in consideration of the influence of error tolerance (toughness); A second function of comparing the first parameter A with a second parameter T considering compression efficiency and error tolerance at the same time; A third function of compressing the macroblock into an intra mode when the first parameter A is larger than the second parameter T according to a comparison result of the second function; And According to the comparison result of the second function, when the first parameter A is not larger than the second parameter T, the first number of bits B1 required for compression in the inter mode and the first time at that time are required. After calculating the error value E1, the number of second bits B2 necessary for the compression in the intra mode, and the second error value E2 at that time, the macroblock is compressed in consideration of the first parameter A. Fourth function to select mode A computer-readable recording medium having recorded thereon a program for realizing this. In an image compression system having a processor, to select a compression mode of a macroblock in which each image frame is divided, A first function of setting a first parameter A in consideration of the influence of error tolerance (toughness); A second function of comparing the first parameter A with a second parameter T considering compression efficiency and error tolerance at the same time; A third function of compressing the macroblock into an intra mode when the first parameter A is larger than the second parameter T according to a comparison result of the second function; And A fourth function of compressing the macroblock in an inter mode when the first parameter A is not larger than the second parameter T according to a comparison result of the second function A computer-readable recording medium having recorded thereon a program for realizing this.