KR19990050063A - Coding Mode Switching Control Device of Image Coding System - Google Patents

Abstract

The present invention relates to an encoding mode switching control device provided in an image encoding system capable of compression encoding an intra mode for encoding an entire image signal corresponding to one screen and an inter mode encoding only a video signal corresponding to a difference between screens. A screen change degree detector configured to store a video signal input from the outside in units of one screen and detect a screen change degree between video signals corresponding to the one screen; An encoder for selectively encoding the video signal in the inter or intra mode; When the encoding unit performs compression encoding in the inter mode, the cumulative value of the screen change degree detected by the screen change degree detection unit is stored. When the encoding unit performs compression encoding in the intra mode, the previously stored screen change degree accumulation value is deleted. A storage unit; A system control unit controlling the encoder to perform encoding in an inter mode only when the screen change degree detected by the screen change degree detection unit is equal to or less than a preset reference value and the cumulative value of the screen change degree stored in the storage unit is equal to or less than a preset reference value. By providing a video encoding mode switching control device, which is included, the screen degradation can be prevented and the compression efficiency can be increased, thereby improving the performance of the video encoding system.

Description

Coding Mode Switching Control Device of Image Coding System

The present invention relates to a video encoding system for compressing and encoding a video signal. More particularly, the present invention relates to a video encoding system in which a variable number of screen configurations of a GOP (group of pictures) can be varied and compressed by changing the compression coding mode of a video signal. An encoding mode switching control apparatus of an encoding system.

With the development of the industry, information media has been developed from text to voice, from voice to video, and more recently from multimedia integrated into it.

On the other hand, the amount of data in each information medium is about 16 kb for 1000 letters and about 8.5 Mb for newspapers, whereas for voice, about 230 Mb and CD (Compact Disc) for 1 hour. About 5.0Gb per hour, and 109Gb for video per hour, 360Gb for current TV, 4320Gb for high-definition TV (aka 'HDTV').

In addition, in order to transmit such information media in real time, voice is about 64kbps, CD (Compact Disc) is about 1.4Mbps, video is about 30Mbps, current TV is about 100Mbps, and high definition TV is about 1.2Gbps. Transmission speed is required.

Therefore, the development of information media inevitably requires the development of communication media and storage media. Such a requirement has been solved by information compression technology. In other words, information compression technology enables the recording of multimedia information such as video images on inexpensive storage media, and can reduce the amount of data occupied on the storage media. Communication is possible at low rates. In addition, high quality video can be transmitted without deterioration in broadcast media, and multi-channel can be achieved.

Such information compression techniques are known to be the most efficient hybrid coding scheme combining probabilistic coding and temporal and spatial compression. These techniques are, for example, MPEG-1, which has already been drafted by the World Standards Organization. And recommendations in MPEG-2 and the like.

In this case, the stochastic coding technique assigns a short code to a high probability of occurrence for a discrete cosine transform (DCT) coefficient or a motion vector and a long code length to a value having a low probability of occurrence. It is a technique to reduce the code length, and the temporal compression technique is a technique that encodes only the information about the moving coordinates (i.e., the motion vector) of the changed part in the full screen by using similarities between neighboring screens. Quantizes one screen into 8 × 8 pixel square blocks, performs DCT transform on each divided square pixel block, and then divides the transformed DCT coefficients by a predetermined number (quantization stem) to round the rest. Is a compression technique.

As described above, since a hybrid encoding scheme uses a correlation with neighboring screens to construct a screen, since only a single screen of information does not form a complete screen, a GOP (Group Of Pictures) structure is used. The data of several prediction screens (inter screens) including one reference screen (intra screens) including information on one screen are grouped into a group.

That is, referring to FIG. 1, which shows an example of an arrangement of picture types in a GOP, one GOP includes a picture of I picture including information about one complete picture, and a B / P including a prediction picture for an I picture. You can see it consists of 14 pictures.

Here, an I picture (Intra Picture) is an intra picture encoded with only one piece of picture information without using inter-frame prediction in order to secure independence of the GOP, and P picture (Predictive-Picture) and B picture (Bidirectionally Predictive). A picture) is an inter picture generated by performing prediction from an I picture that is an intra picture.

However, since the GOP according to the related art described above is composed of a fixed number of screens regardless of the degree of change between screens, screen degradation may occur when the degree of change between screens such as scene change is severe. If the degree of change in the liver is very fine, there was a problem that the compression efficiency is lowered.

Accordingly, the present invention has been made in view of the above-described problems, and an object of the present invention is to switch the compression encoding mode to correspond to the degree of change of the screen, and to control the compression encoding mode in consideration of the cumulative value of the change of the original picture. The present invention provides an encoding mode switching control apparatus of a video encoding system configured to perform switching control.

In order to achieve the above object, in the present invention, the video encoding system capable of compression coding in the intra mode for encoding the entire video signal corresponding to one screen and the inter mode for encoding only the video signal corresponding to the difference between screens. An encoding mode switching control device provided in the apparatus, the apparatus comprising: a screen change degree detector configured to store a video signal input from an external unit in one screen unit and then detect a screen change degree between video signals corresponding to the one screen; An encoder for selectively encoding the video signal in the inter or intra mode; When the encoding unit performs compression encoding in the inter mode, the cumulative value of the screen change degree detected by the screen change degree detection unit is stored. When the encoding unit performs compression encoding in the intra mode, the previously stored screen change degree accumulation value is deleted. A storage unit; A system control unit controlling the encoder to perform encoding in an inter mode only when the screen change degree detected by the screen change degree detection unit is equal to or less than a preset reference value and the cumulative value of the screen change degree stored in the storage unit is equal to or less than a preset reference value. Provided is an image encoding mode switching control device.

1 is an exemplary diagram showing an example of a screen type arrangement in a GOP according to the prior art;

2 is a block diagram showing an encoding mode switching device of a video encoding system according to the present invention;

FIG. 3 is an exemplary diagram illustrating each configuration and relationship of macroscreens, blocks, and pixels in one screen for NTSC and one screen for explaining a method of detecting a screen change degree according to the present invention; FIG.

<Description of the symbols for the main parts of the drawings>

100: frame memory 200: screen change detection unit

210: memory switching unit 220: first memory

230: second memory 240: gradient calculation unit

300: system control unit 400: storage unit

500: encoder 510: mode switching unit

520: intra encoder 530: inter encoder

The above and other objects and advantages of the present invention will be more clearly apparent from the following description taken in conjunction with the accompanying drawings.

Hereinafter, the encoding mode switching control apparatus of the image encoding system according to the present invention will be described in detail with reference to FIGS. 2 to 3.

2 is a block diagram illustrating an encoding mode switching control apparatus of an image encoding system according to an exemplary embodiment of the present invention. As shown in the figure, an encoding mode switching control apparatus of an image encoding system according to an exemplary embodiment of the present invention is a frame memory 100. The screen change detection unit 200, the system control unit 300, the storage unit 400, and the encoding unit 500 are configured to include the functions of the respective members as follows.

First, the frame memory 100 sequentially stores image signals input from the outside, and when information on one screen is completed, the memory switch unit 210 provided in the screen change detection unit 200 stores information about one screen. ) Is provided to the first memory 220 or the second memory 230 by switching.

In addition, the intra encoder 520 or the inter encoder 530 may be provided with information about one screen stored by the mode switcher 510. In this case, the information on one screen refers to an image signal of one screen and will be referred to as information on one screen.

The screen gradient detector 200 includes a memory switch 210, a first memory 220, a second memory 230, and a gradient calculator 240, and includes a current screen provided from the frame memory 100. The screen change degree of the previous screen is detected, and information about the detected screen change degree is provided to the system controller 300. In order to perform such a function, each component of the screen change detector 200 again performs the following function.

First, the memory switching unit 210 is switched under the control of the system control unit 210 so that information about one screen provided from the frame memory 100 is stored in the first memory 220 or the second memory 230. The frame memory 100 and the first memory 220 or the second memory 230 are connected to each other.

By switching of the memory switching unit 210, information of one screen unit provided from the frame memory 100 is alternately stored in the first memory 220 and the second memory 230.

That is, when information of one screen unit provided in odd-numbered times in the frame memory 100 is stored in the first memory 220, such as 1, 3, 5, 7, ,,,, The information of one screen unit provided even in the frame memory 100 is stored as 2, 4, 6, 8 ,,,,.

Meanwhile, the gradient calculator 240 calculates a screen gradient by comparing the screen information stored in the first memory 220 with the screen information stored in the second memory 230.

The system controller 300 checks the order in which the information about the screen is provided in the frame memory 100, and controls the memory switcher 210 to switch according to the check result.

In addition, the system controller 300 stores the reference value of the screen change degree and the cumulative change degree reference value in an internal memory (not shown) provided therein, and information on the change degree between the screens from the screen change degree detection unit 200. If is provided, the screen change degree between the screen change degree detection unit 200 and the reference value of the screen change degree stored in the internal memory (not shown) is compared.

As a result of the comparison, the system controller 300 may encode the information about one screen provided by the frame memory 100 in the intra mode when the screen change degree is greater than the reference value. If the screen change degree is smaller than the reference value, the cumulative value of the screen change degree stored in the storage unit 400 and the cumulative change degree reference value stored in the internal memory (not shown) are controlled. Is compared to control the mode switching unit 510 provided in the encoder 500 corresponding to the comparison result. In this case, if the cumulative value of the screen change degree is less than the cumulative change degree reference value, the system controller 300 includes a mode clause provided in the encoder 500 to encode information about one screen provided by the frame memory 100 in an intra mode. The mode switching unit provided in the encoder 500 to control the affected part 510 and to encode information about one screen provided from the frame memory 100 in an inter mode when the cumulative value of the screen change degree is greater than the cumulative change degree reference value. While controlling the display device 510, the screen change degree detected by the screen change degree detection unit 200 is accumulated and added to the total of the previous screen change degrees stored in the storage unit 400, and then the added screen change also accumulates. To store in the storage 400.

The storage unit 400 stores information on the cumulative value of the screen change degree.

The encoder 500 includes a mode switcher 510, an intra encoder 520, and an inter encoder 530. One screen provided from the frame memory 100 under the control of the system controller 300. The encoding of the information on the intra mode or the inter mode is selectively performed, and each component constituting the encoder 500 performs the following functions.

First, the mode switching unit 510 is connected to the frame memory 100 and the intra encoder 520 or the inter encoder 530 under the control of the system controller 300, and is provided from the frame memory 100. Information about one screen is provided to the intra encoder 520 or the inter encoder 530.

The intra encoder 520 encodes and outputs the entire information of one screen unit provided from the frame memory 100, and the inter encoder 530 of the screen unit information provided from the frame memory 100 and the previous screen of the information. The information is subtracted, and only the difference value is encoded and output.

The operation of the sub-code mode switching control apparatus of the image encoding system according to the present invention including the constituent member for performing the above function will be described with reference to FIG. 3 with reference to FIG. 2.

FIG. 3 is an exemplary diagram illustrating each configuration and relationship of one screen for NTSC and macroblocks, blocks, and pixels in one screen for explaining a method of detecting a screen change degree according to the present invention.

First, when a video taken by a video camera is converted into digital information from an analog signal and then applied to the frame memory 100, the applied digital information is sequentially stored in the frame memory 100, and then the basic information of the image information constituting the screen is displayed. Decomposition is performed in units of pixels. In this case, each pixel has a luminance and a color difference, and as shown in FIG. 3, each pixel may be expressed as a pixel value for each pixel.

Subsequently, when digital information sequentially stored constitutes one screen, the frame memory 100 includes information about one screen sequentially stored in the memory switching unit 210 and the encoder 500 included in the screen change diagram. To the configured mode switching unit 510.

At this time, the system controller 300 checks the order in which information about one screen from the frame memory 100 is provided to the memory switcher 210, and controls the memory switcher 210 to correspond to the check result. That is, when the order in which information about one screen from the frame memory 100 is provided to the memory switching unit 210 is an odd number of 1, 3, 5, 7,, the memory is connected to the first memory 220. The switching unit 100 is controlled to be switched, and when the second, fourth, sixth, eightth, ,, even numbers are even, the memory switching unit 100 is controlled to be connected to the second memory switching unit 210.

Therefore, when information about the first screen is provided from the frame memory 100 to the memory switcher 210, the system controller 300 controls the memory switcher 210 to be connected to the first memory 220. The memory switching unit 210 is connected to the first memory 220 under the control of the system control unit 300.

As the memory switching unit 210 is stored in the first memory 220, information about the first screen provided from the frame memory 100 is stored in the first memory 220.

Thereafter, when information about the second screen is provided from the frame memory 100 to the memory switcher 210, the system controller 300 controls the memory switcher 210 to be connected to the second memory 230. The memory switching unit 210 is connected to the second memory 230 under the control of the system control unit 300.

As the memory switching unit 210 is stored in the second memory 230, information about two screens provided from the frame memory 100 is stored in the second memory 220.

As described above, when the screen information is stored in the first memory 220 and the second memory 230, the gradient calculator 240 may display the screen information stored in the first memory 220 and the screen information stored in the second screen. Referring to FIG. 6, the screen change degree of the first screen and the second screen provided from the frame memory 100 is detected.

In one embodiment of the present invention, the screen information stored in the first memory 220 and the pixel values of the total pixels constituting the screen information stored in the second memory 230 are summed, and then, the first memory 220 is summed. The difference between the total pixel value of the stored screen and the total pixel value of the screen stored in the second memory 230 is calculated. In this case, the difference of the total pixel values may be the screen change degree.

Meanwhile, according to another exemplary embodiment of the present invention, the pixel values of the total pixels constituting the screen information stored in the first memory 220 and the screen information stored in the second memory 230 are respectively 16 × 16 pixels. After dividing by) unit, a difference value is calculated between the divided macro blocks of the same position, and the sum of the calculated difference values in the macro block unit is stored in the first memory 220 and the second memory 230. The degree of change of the screen may be detected as the average difference divided by the total number of macroblocks constituting the information.

In addition to the first screen information and the second screen information stored in the first memory 220 and the second memory 230, the first memory 220 and the second memory 230 are alternated by the above-described operation process. Compared with the previous screen information and the current screen information, such as the second screen information and the third screen information, the third screen information and the fourth screen information, the fourth screen information and the fifth screen information, which are stored as Detect.

When the screen change degree detected by the screen change degree detecting unit 200 is provided to the system control unit 300 by the above-described process, the system control unit 300 changes the screen change degree reference value and the screen change stored in the internal memory (not shown). The degree of screen change provided by the detector 200 is compared.

As a result of the comparison, if the screen change degree provided by the screen change degree detecting unit 200 is larger than the reference value, the system controller 300 determines that the change between the screens is large, and the mode switching unit 510 included in the encoder 500 is determined. The switching control will be performed to connect to the intra encoder 520, and the mode switch 510 is connected to the intra encoder 520 under the control of the system controller 300.

Therefore, information about one screen provided from the frame memory 100 will be provided to the intra encoder 520, and the intra encoder 520 will differentiate the information about one screen provided from the frame memory 100. Instead of using it, compression coding is performed on the entire screen to be output.

On the other hand, if the screen change degree provided by the screen change degree detecting unit 200 is smaller than the reference value as a result of the comparison of the system control unit 300, the system control unit 300 accumulates the previous screen change degree stored in the storage unit 400. The accumulated total and the cumulative change stored in the internal memory (not shown) are also compared. At this time, the cumulative total of the screen change degree stored in the storage unit 400 is the mode switch unit 510 in a state in which the cumulative value of the screen change degree is deleted and reset to 0 when the mode switcher 510 switches to the intra mode. Is changed to the inter mode, and the screen change degree detected by the screen change degree detecting unit 200 is accumulated.

As a result of comparing the cumulative total of the screen change degree with the reference value of the cumulative change degree, the system controller 300 determines that the cumulative total of the screen change degree is greater than the reference value of the cumulative change degree. ) Is controlled to be connected to the intra encoder 520, and the mode switch 510 is connected to the intra encoder 520 under the control of the system controller 300.

Therefore, information about one screen provided from the frame memory 100 will be provided to the intra encoder 520, and the intra encoder 520 will differentiate the information about one screen provided from the frame memory 100. Instead of using it, compression coding is performed on the entire screen to be output.

On the other hand, as a result of comparing the cumulative total of the screen gradient and the reference value of the cumulative gradient, the system controller 300 determines that the mode section provided in the encoder 500 is smaller than the reference value of the cumulative gradient. The switching unit 510 is controlled to be connected to the inter encoder 530, and the mode switching unit 510 is connected to the inter encoder 530 under the control of the system controller 300.

Accordingly, information about one screen provided from the frame memory 100 will be provided to the inter encoder 520, and the inter encoder 530 transfers information about one screen provided from the frame memory 100 to the previous information. Compared with the screen information, the difference is encoded and output as the difference value.

In addition, the system controller 300 switches the mode switching unit 510 to the inter encoder 530, and detects the screen change degree detection unit 200 as a cumulative sum of the screen change degrees stored in the storage unit 400. The current screen change degree is added and stored in the storage unit 400 again.

According to the present invention described above, by performing selective encoding in inter or intra mode corresponding to the inter-screen variation of the input video signal and the cumulative variation from the reference screen, the compression efficiency can be improved and the screen degradation can be prevented. This has the effect of improving the performance of the video encoding system.

Claims (5)

An encoding mode switching control device provided in a video encoding system capable of compression encoding an intra mode for encoding an entire video signal corresponding to one screen and an inter mode for encoding only a video signal corresponding to a difference between screens. A screen change detector configured to store a video signal input from the outside in units of one screen and detect a screen change degree between video signals corresponding to the one screen; An encoder for selectively encoding the video signal in the inter or intra mode; When the encoding unit performs compression encoding in the inter mode, the cumulative value of the screen change degree detected by the screen change degree detection unit is stored. When the encoding unit performs compression encoding in the intra mode, the previously stored screen change degree accumulation value is deleted. A storage unit; A system control unit controlling the encoder to perform encoding in an inter mode only when the screen change degree detected by the screen change degree detection unit is equal to or less than a preset reference value and the cumulative value of the screen change degree stored in the storage unit is equal to or less than a preset reference value. An image encoding mode switching control device comprising. The display device of claim 1, wherein the screen change detection unit comprises: First and second memories for storing the video signal corresponding to one screen; A memory switching unit for connecting and switching the image signal to the first or second memory; A change degree calculator configured to calculate a change degree between the image signals stored in the first and second memories, The system control unit, And the memory switching unit is controlled to alternately apply the image signal to the first memory and the second memory. The method of claim 1, wherein the encoding unit, An intra encoder for encoding the video signal in an intra mode; An inter encoder for encoding the video signal in an inter mode; And a mode switcher for selectively connecting the video signal to the intra or inter encoder under the control of the system controller. The screen change detection unit according to any one of claims 1 to 3, After dividing the video signal stored in the first and second memory in units of macro blocks of 16 × 16 pixels, and calculating the difference value of the video signals stored in the first and second memories in units of the divided macro blocks, And the change degree is detected by calculating the average value of the calculated difference values. The screen change detection unit according to any one of claims 1 to 3, wherein The sum of the pixel values of the pixels constituting the image signal stored in the first and second memories, respectively, is summed, and then the degree of change is detected by the difference of the sum of the summed pixel values. controller.