KR20160109617A - Decoding apparatus of digital video - Google Patents

Abstract

The present invention discloses an apparatus for decoding a digital video, which performs preprocessing decoding on an overall screen and performs main decoding, adapted to achieve the level of an original video, on an area of interest in the overall screen, and thus a video can be smoothly provided without delay even in a decoding apparatus having low processing power. The apparatus for decoding a digital video according to the present invention comprises: a first decoding unit which performs preprocessing decoding on a bit stream of a video for an overall area of a screen, and outputs first video data filling the overall area with essential pixels having encoded values used only once in the preprocessing decoding; an area-of-interest setting unit which sets a predetermined area of interest in an overall area of the first video data, and outputs video data of the set area of interest; and a second decoding unit which performs main decoding on the video data of the area of interest so that the video data is decoded into original values, and outputs second video data in which the area of interest has been restored to an original state thereof.

Description

[0001] DESCRIPTION [0002] Decoding apparatus of digital video [

The present invention relates to a digital video decoding apparatus, and more particularly, to a digital video decoding apparatus that performs pre-processing decoding on a full screen and performs main decoding at an original level for a region of interest in the entire screen.

A method of compressing and decompressing an image of a digital video typically uses an MPEG standard or a modification method. Here, the transformation method is not largely different from the core data saving method based on the method of dividing the screen into blocks and storing only the difference between the reference block and the current block.

In the method of compressing data using a temporal model, only the information of the changed part is referred to by cross-referencing the image information which changes with time, and the image of the part without change is used as the reference image (i.e., Intra Frame) . The two adjacent still images forming the moving picture are substantially similar to each other, and the compression method using the temporal model has a great effect.

When compressing an image, each image frame is compressed through a method such as intra frame (I frame), prediction frame (P frame), bidirectional prediction frame (B frame), and the like.

An intra frame (I frame) is a frame that is independently compressed / reconstructed without using data of previous or subsequent frames. The first frame in the video sequence is always an intra frame (I frame), and an intra frame (I frame) can be used for a new viewer or when specifying the starting point of a resynchronization point if the transmitted bit stream is corrupted.

The prediction frame (P frame) is generated by the forward prediction from the previously already intra-frame (I frame) or prediction frame (P frame). Therefore, it is impossible to generate a predictive frame (P frame) if there is no previously generated frame. The prediction frame (P frame) requires less bits than the intra frame (I frame), but has a disadvantage in that it is sensitive to transmission errors due to complex dependence on the previous prediction frame (P frame) and intra frame (I frame).

A bidirectional prediction frame (B frame) is a frame constructed by referring to two or more frames. (I frame) or a prediction frame (P frame) to be decoded, a bidirectional predictive frame (B frame) generated by referring to a previously generated intra frame (I frame) And a bidirectional prediction referring to the forward and backward modes.

The compression standard related to the above-mentioned frames is H.264 (also referred to as MPEG-4 Part 10 / AVC for advanced video coding), which is designed to reduce the size of image files while minimizing image quality degradation.

H.264 is an approved open standard that supports image compression technology. H.264 encoders can reduce digital image file sizes by 80% and 50%, respectively, without compromising image quality when compared to Motion JPEG format and MPEG-4 Part 2 standard. This means that a small amount of network bandwidth and storage space is required for the image file.

H.264 has already been introduced in electronic devices such as mobile phones and digital video players, and has received high praise from actual consumers. Service providers such as online video storage and telecommunication companies are also adopting H.264.

In the video security industry, H.264 has a 30 per second (NTSC) frame transmission implementation that can have a significant impact on installation sites where high frame rates and high picture quality are required, such as highway, panic and casino surveillance. This is because bandwidth reduction and economical storage space can provide cost savings.

H.264, on the other hand, can accelerate the adoption of a megapixel camera because efficient compression technology can reduce large file sizes and bit rates without compromising image quality.

H.264 is the name used by ITU-T, while ISO / IEC names it MPEG-4 Part 10 / AVC because it is presented as a new part of MPEG-4 by the agency. For example, MPEG-4 includes MPEG-4 Part 2, a standard used by IP-based video encoders and network cameras.

H.264, designed to address several of the disadvantages of previous video compression standards, is a technology that can be flexibly applied to a wide range of bit-rate-requiring scenarios. For example, in the video market including broadcasting, satellite, cable and DVD, H.264 can exhibit a performance of 1 to 10 Mbit / s with high latency, whereas communication service has a low H.264 of 1 Mbot / s Lt; / RTI >

In the basic file of H.264, only the intra frame (I frame) and the prediction frame (P frame) are used, and since the bidirectional prediction frame (B frame) is not used, it is suitable for network camera and video coding Do.

In the H.264 image compressing method, for example, only the motion information of the changed part compared to the previous image or the reference image is detected, and the corresponding part can save the data by providing only the coordinate information instead of the image information.

Also, when decompressing, decompression can be performed using only the above-mentioned coordinate information. Due to such a compression or decompression structure, information on a previous image and a reference image is required in order to construct a current image.

A video coding method for CCTV images in various digital video fields will be described as an example. CCTV images are rapidly increasing in demands for video resolution, ranging from SD to UHD, and demand for videos is increasing at the same level as panorama 180 degrees and fish eye 360 degrees.

In this case, the wide-angle fish eye-based video image is concentrated on the edge of the screen. In order to obtain the resolution of the SD level, a resolution of 2 Mega Pixel or 3 Mega Pixel is required for a Fish Eye-based original video image , And recently, the demand for 5 Mega Pixel or 8 Mega Pixel is increasing rapidly.

In order to decode a video image of several megapixels, a considerable amount of control resources are consumed. For this reason, the above-described fish eye-based video playback can not be smoothly performed through a PC of a high-specification PC or a server specification. to be.

For example, when the inputted video image is 3 Mega Pixel, the control resource for decoding requires the capability to handle all 3 million pixels. Accordingly, there is a limit in that a decoding apparatus that receives a video image of 3 Mega Pixels can not perform video reproduction or smoothly process it in a state where it does not have control resources capable of processing all 3 million pixels.

Furthermore, even if the input video image is a video image of a high specification so as to reach 3 Mega Pixels, even if the image output through the decoding and output to the actual user screen corresponds to a very small portion of 3 Mega Pixel, There are some unreasonable reasons to have control resources to handle all 3 million pixels.

Korean Registered Patent No. 10-0701740 (Mar. 23, 2007)

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a video decoding apparatus and a video decoding method, The video decoding apparatus of the present invention can provide smooth video images without delay.

The objects of the present invention are not limited to the above-mentioned problems, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided a digital video decoding apparatus that performs a preprocessing decoding on a bitstream of a received video image, and extracts necessary pixels for image display as a result of the preprocessing decoding, And a second decoding unit for restoring the image data corresponding to the region of interest to an original state, the first decoding unit displaying the entire area of the screen with the restored pixels, the interest area setting unit setting the predetermined area of interest among the entire area of the screen, .

And an extra area setting unit for further setting an extra area with a predetermined standard as an external area adjacent to the area of interest.

The spare area setting unit varies the size of the spare area according to the size of a motion vector analyzed through a prediction frame (i.e., P frame) or the movement of the ROI.

Therefore, in the present invention, by performing pre-processing decoding on the entire screen and main decoding at the original level for the region of interest in the entire screen, even if the inputted video image is an advanced video image, There is an advantage in that a decoding device that does not have the control resource having the control resource can decode the image of the user's required part.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description of the claims.

1 is a block diagram showing a decoding apparatus according to an embodiment of the present invention.
FIG. 2 is a block diagram showing the first decoding unit of FIG. 1 as an embodiment.
FIG. 3 is an image showing an original image of a bitstream input to the first decoding unit of FIG. 1 as an embodiment.
FIG. 4 is an image showing the first image data processed by the first decoding unit of FIG. 1 as an embodiment.
FIG. 5 is an image showing a state in which a region of interest is set in the first image data of FIG. 4 as an embodiment.
FIG. 6 is an image showing, by way of example, image data of a region of interest in FIG.
FIG. 7 is a block diagram showing the second decoding unit of FIG. 1 as an embodiment.
8 is a block diagram illustrating a decoding apparatus according to another embodiment of the present invention.
9 is an image of an embodiment output from the second decoding unit of FIG.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Further, the embodiments described herein will be described with reference to cross-sectional views and / or schematic drawings that are ideal illustrations of the present invention. Thus, the shape of the illustrations may be modified by manufacturing techniques and / or tolerances. In addition, in the drawings of the present invention, each component may be somewhat enlarged or reduced in view of convenience of explanation.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing a decoding apparatus according to an embodiment of the present invention.

Referring to FIG. 1, the decoding apparatus 100 receives a bitstream that is a compressed state of an original image, performs pre-processing decoding on the entire bitstream with respect to the received bitstream, Decoding is performed.

Here, the original level means that the video decoding is performed in a standard manner according to the existing video coding standards (for example, MPEP-4, H.264, and H.265) without any special need in the video decoding process.

The decoding apparatus 100 includes a first decoding unit 110, a region-of-interest setting unit 120, and a second decoding unit 130.

The first decoding unit 110 performs preprocessing decoding on the bitstream of the received video image, and represents the entire screen region as a required pixel for image display and a non-reconstructed pixel as a result of the preprocessing decoding.

In the preprocessing decoding process of the first decoding unit 110, it is possible to display the entire screen area separated by the above-described essential pixels and non-restored pixels through an inverse transformation process.

Here, DCT (Discrete Cosine Transform) used in the inverse transform process separates the pixel values spreading on the screen before the conversion into the low frequency and high frequency regions after the orthogonal transformation. Due to the human color recognition ability of each frequency band, Refers to a technique of deriving image compression by discarding data of a region and taking data in a low frequency region to perform coding.

That is, when the DCT transform is performed, the bit stream of the received video image is changed from the spatial domain to the frequency domain, and when viewed in such a frequency domain, data (signal) is crowded into a region having a low frequency.

In the frequency domain, there is often a similar color between adjacent pixels. For example, when an 8x8 block is DCT, the same color among 64 pixels is concentrated on a lower frequency (DC). When there is a change in color, it is located at a high frequency (AC).

The DC component data and the AC component data are analyzed through the analysis of the frequency domain before the conversion in the inverse transformation process of the first decoder 110, .

By using this, it can be determined that the data (signal) of the AC component exists, which corresponds to a necessary pixel for image display.

In the case where data (signal) of the DC component exists, it can be determined that the DC component corresponding to the color average value corresponds to a case where the colors of adjacent pixels are similar. In other words, the data (signal) of the DC component can be managed by non-restored pixels that are not subjected to arithmetic processing, which need not be expressed in detail. Here, the non-restored pixel can be managed as an empty pixel having no calculated value and can be displayed in the entire area of the screen.

For example, when an intra frame (I frame) of a bit stream of a video image is pre-processed and decoded, a current block to be decoded is specified, and then the vertical and horizontal Direction, the diagonal direction, and the like of the current block of the decoding target. Herein, the copying of the current block to be decoded is not an original level restoration according to the H.264 standard, the essential pixels having the encoded values not to be reused in the pre-processing decoding are copied and filled in the current block of the decoding target , The non-essential pixel portion is left with a predetermined size (e.g., 16x16) block filled with an uncomputed blank block (e.g., a black pixel or a white pixel)).

This empty block is a pixel having no actual data value, meaning that both the luminance and chrominance values are set to 0 or the maximum value (255 when the pixel has 0 to 255 gradations).

The interest region setting unit 120 sets a predetermined region of interest of the first image data output from the first decoding unit 110 and outputs image data of a predetermined region of interest.

The second decoding unit 130 mainly decodes the image data of the region of interest into the original restored value and outputs the second image data that restores the region of interest to the original state level.

FIG. 2 is a block diagram illustrating the first decoding unit 110 of FIG. 1 as an embodiment.

Referring to FIG. 2, the first decoding unit 110 performs all necessary steps required for decoding digital video. For example, in addition to performing parsing, entropy decoding, and zigzag scanning according to the H.264 standard, dequantization, inverse transform, motion compensation, and image composition are performed when the frame to be decoded is an intra frame (I frame) , And the decoding target frame is a predictive frame (P frame), the steps of inverse quantization, inverse transform, motion compensation, and image composition can be sequentially performed.

However, instead of restoring the frames to be decoded to the original level according to the H.264 standard, the first decoding unit 110 sequentially executes the respective required steps according to the H.264 standard, and reduces the decoding load to a minimum The entire area of the screen is filled with only the necessary pixels having an un-reused encoding value, and the parts other than the essential pixels are filled with the uncalculated values.

That is, the first decoding unit 110 includes a parsing module 111, an entropy decoding module 112, a scan module 113, an inverse quantization module 114, an inverse transformation module, a motion compensation module 116, 117).

The parsing module 111 receives the bitstream of the original image and prepares the preprocessing decoding.

The entropy decoding module 112 performs lossless decoding on the input bitstream, and obtains motion vectors and texture data. Lossless decoding includes Huffman block decoding, arithmetic decoding, and variable length decoding. In general, a motion vector for a certain macroblock depends on a motion vector of a neighboring macroblock. That is, a motion vector of a specific macroblock can not be obtained without obtaining a motion vector of a neighboring macroblock. The texture data obtained by the entropy decoding module 112 may be provided to the dequantization module 114 and the motion vector may be provided to the motion compensation module 116.

The inverse quantization module 114 performs inverse quantization on the texture data provided from the entropy decoding module 112. The dequantization process refers to a process of recovering a value matching the index generated in the quantization process using the quantization table used in the quantization process.

The inverse transform module 115 performs an inverse transform on the inverse quantized result. The inverse discrete cosine transform (DCT) and inverse wavelet transform (DCT) are the specific methods of the inverse transform.

The motion compensation module 116 performs motion compensation using at least one reference frame (previously restored and stored in the picture buffer) using a motion vector for the current macroblock provided from the entropy decoding module 112 And generates a predicted image by performing motion compensation. When the motion compensation is performed in units of 1/2 pixel or 1/4 pixel, a large amount of calculation is required in the interpolation process for generating the predicted image. In addition, when motion compensation is performed using two reference frames, an average of motion compensated macroblocks is calculated. In this case, there is a dependency between the macroblocks. Therefore, these macroblocks need to be processed in a single core.

The image configuration module 117 represents the image of the result of the preprocessing decoding.

FIG. 3 is an image showing an original image of a bitstream input to the first decoding unit 110 of FIG. 1 as an example. FIG. 4 is a diagram illustrating an example of a first image data processed by the first decoding unit 110 of FIG. Is an image represented by an embodiment.

Referring to FIGS. 3 and 4, the first decoding unit 110 receives the bitstream in a state in which the original image is encoded as shown in FIG. 3, and outputs the first image data of the result of the pre-decoding as shown in FIG.

FIG. 5 is an image showing a state in which a region of interest is set in the first image data of FIG. 4, and FIG. 6 is an image showing image data of a region of interest in FIG.

Referring to FIG. 5, the region-of-interest setting unit 120 sets a predetermined region of interest for the first image data of the pre-processing decoding result as shown in FIG. 4 as shown in FIG. 5 and outputs image data of the set region of interest.

The image data of the region of interest output from the region of interest setting unit 120 is left as an empty pixel representing the required pixels representing the image in the region of interest and an uncomputed region as shown in Fig.

The DC component data and the AC component data are analyzed through the analysis of the frequency domain before the conversion in the inverse transformation process of the first decoder 110, .

By using this, it can be determined that the data (signal) of the AC component exists, which corresponds to a necessary pixel for image display.

In the case where data (signal) of the DC component exists, it can be determined that the DC component corresponding to the color average value corresponds to a case where the colors of adjacent pixels are similar.

That is, the above-mentioned empty block can be defined as a part corresponding to the data (signal) of the DC component in the inverse transformation process of the first decoding unit 110. [

FIG. 7 is a block diagram illustrating the second decoding unit 130 of FIG. 1 as an embodiment.

Referring to FIG. 7, the second decoding unit 130 receives the image data of the ROI output from the ROI setting unit 120, and decodes the input image data of the ROI into an original restored value at the time of encoding And then outputs the second image data obtained by restoring the ROI to the original state as a result.

8 is a block diagram showing a decoding apparatus 100 according to another embodiment of the present invention.

Referring to FIG. 8, the decoding apparatus 100 receives a bitstream that is a compressed state of an original image, preprocesses and decodes the entire bitstream of the received bitstream, and extracts a region of interest And the main decoding is performed at the original level up to the spare area further enlarged by a predetermined standard.

The decoding apparatus 100 includes a first decoding unit 110, a region of interest setting unit 120, a reserved area setting unit 120, and a second decoding unit 130.

The first decoding unit 110 preprocesses and decodes a bit stream of the video image to the entire area of the screen, and outputs first video data representing the entire area of the screen to a necessary pixel having an encoding value that is not reused in the current pre- do.

The region-of-interest setting unit 120 sets a predetermined region of interest of the first image data output from the first decoding unit 110 to indicate a predetermined region of interest.

The spare area setting unit 120 further sets a spare area in which the region of interest set by the region of interest setting unit 120 is further expanded to a predetermined standard. For example, the spare area setting unit 120 can set a spare area that is 10% to 20% more extended in the area of interest.

In addition, the spare area setting unit 120 may change the spare area in consideration of the size of the motion vector or the movement of the ROI. For example, if the size of the motion vector is large or the moving range of the ROI is large, the spare area setting unit 120 can expand the spare area to 20%. If the size of the motion vector is small, If the width is small, the spare area can be extended to 10%.

Thus, the need for spare areas can be said to be greater in the P and B frames than in the I frames. Since the I frame is a frame that is reconstructed without referring to other frames, it is possible to restore only a minimum number of peripheral pixels (left and upper pixels) from the region of interest, so that a spare area may not be necessary. However, The reference position of the previous or subsequent frame should be referred to, and if the referenced position is an empty block, the reconstruction quality of the image may deteriorate. Therefore, in the case of P and B frames, it is necessary to set the spare area in consideration of the size of the range in which the motion vector is searched, in order to properly restore the P and B frame of interest.

The second decoding unit 130 mainly decodes the image data of the interest area and the spare area into the original restored value and outputs the second image data that restores the area of interest and the spare area to the original state level.

FIG. 9 is an image of an embodiment output from the second decoding unit 130 of FIG.

The second decoding unit 130 receives the image data of the reserved area set from the interest area setting unit 120 and the image data of the inputted interest area and the spare area, The main decoding is performed with the original restoration value at that time, and as a result, the second image data in which the ROI and the spare area are restored to their original state is output. For example, the second image data output from the second decoding unit 130 may be the image shown in FIG.

Meanwhile, in the above embodiments, it has been described that empty blocks are included in areas other than the ROI, but it is necessary to fill the pixel values into a natural image rather than leaving such blank blocks in view of the image. As a method of restoring the pixel value belonging to the empty block, the blank block may be filled with the same pixel as the block on the left or upper side of the current empty block in consideration of the scanning direction, or in the same manner as in the intra prediction mode of H.264, The empty block may be filled by adjacent pixels on the left or upper side. If the referenced neighboring block or neighboring pixel is also an empty block, it may refer to the left or upper block or adjacent pixel.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

Further, the present invention is to provide a digital video decoding apparatus that performs pre-processing decoding on a full screen and performs main decoding at an original level for a region of interest on the entire screen, It is an invention that can be used industrially because it is practically possible to carry out clearly.

100: decoding apparatus 110: first decoding unit
120: ROI setting unit 130: Second decoding unit
111: parsing module 112: entropy decoding module
113: scan module 114: dequantization module
115: Inverse transform module 116: Motion compensation module
117: image configuration module

Claims (3)

A first decoding unit that performs pre-processing decoding on a bitstream of a received video image, and as a result of the preprocessing decoding, an entire screen region as a required pixel for image display and a non-restored pixel that is not processed;
A region of interest setting unit that sets a predetermined region of interest among the entire region of the screen; And
And a second decoding unit for restoring the image data corresponding to the ROI to an original state. The method according to claim 1,
Further comprising a spare area setting unit for setting a spare area with a predetermined standard as an outside area adjacent to the area of interest,
Wherein the spare area setting unit varies the size of the spare area according to the size of the motion vector analyzed from the bit stream or the movement of the ROI. 3. The method of claim 2,
Wherein the spare area is further set when it is a specific frame that refers to a frame at a different temporal position.

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