1. Field of the Invention
The present invention relates to a video information coding method using an object boundary block merging/splitting technique, and in particular, to an improved video information coding method using an object boundary block merging/splitting technique which makes it possible to more effectively merge and code an object boundary block using a space surplus of a video or between videos existing in a block or between blocks and split the video through an object block splitting technique for a reconstruction of a recovering video and a display.
2. Description of the Conventional Art
Recently, the MPEG (Motion Picture Experts Group) which introduced an MPEG-I and MPEG-II which are an international standard recommendation with respect to a video and audio coding technique and system construction plans to introduce in 1998 an MPEG-IV to be used as a new international standard recommendation with respect to a new generation video and audio coding technique and system construction.
The MPEG-IV is directed to supporting a next generation video and audio application which can not be supported by the previous MPEGs.
In addition, the MPEG-IV includes a new technique for a communication and connection of a video and audio data, for example, an object-based interactive function and connection function through a network having a different characteristic.
Furthermore, it is possible to provide a characteristic by which the system operates under a predetermined communication environment such as an erroneous communication environment and a low transmission ratio.
Moreover, it is possible to code and control a natural video and audio and an artificial video and audio by using a computer graphic technique.
Namely, the MPEG-IV is capable of supporting many functions required in various applicable fields.
Therefore, the MPEG-IV may provide an open structure which is capable of supporting functions required for low cost and high-tech applicable fields as the multimedia technique advances and expandable functions.
Among the functions, there is known a function of enhancing a compression efficiency for a coding effect which is needed for a transmission and storing function and cost reduction.
As applicable fields with respect to the MPEG-IV, there are known a NDB (Networked Database Service) using an IMM (Internet Multimedia), an IVG (Interactive Video Games), an IPC (Interpersonal Communications), an ISM (Interactive Storage Media), an MMM (Multimedia Mailing), a WMM (Wireless Multimedia), an ATM, etc., an RES (Remote Emergency System), and an RVS (Remote Video Surveillance, etc.
In order to support an existing application and an next generation application, a video coding technique is needed so that a user communicates with a desired destination in a predetermined video region, searches and accesses a desired destination and edits the same.
Namely, the MPEG-IV which is to be completed in 1999 as a new video and audio coding technique is basically directed to satisfying the above-described desires.
FIG. 1 illustrates the construction of a video coding unit for an MPEG-IV, which has different construction from H.261, H.263, MPEG-I, and MPEG-II which are international standards for a video coding technique.
Namely, the video coding unit of the MPEG-IV is directed to estimating a motion by the macro block unit as a VOP with respect to an object video formed by a VOP formation unit 10 is inputted into a motion estimation unit 11.
In addition, the motion information estimated by the motion estimation unit 11 is inputted into a motion compensation unit 12, thus compensating the motion.
The VOP the motion of which is compensated by the motion compensation unit 12 is inputted into a subtractor 13 together with a VOP formed by the VOP formation unit 10, thus measuring a difference value therebetween, and the thusly measured difference value by the subtractor 13 is inputted into a video signal coding unit 14, so that a video signal of an object is coded by the sub-block unit of a macro block.
For example, the video signal coding unit 14 splits the X-axis and Y-axis of a macro block into 8.times.8 sub-blocks each having 8 pixels, thus coding the video signal of the object.
In addition, the VOP the motion of which is compensated by the motion compensation unit 12 and an internal information of an object coded by the video signal coding unit 14 are inputted into an adder 15, and an output signal from the adder 15 is inputted into a previously reconstructed VOP 16, thus detecting a VOP of a previous display.
The VOP of the previous display detected by the VOP detection unit 16 is inputted into the motion estimation unit 11 and the motion compensation unit 12 and is used for a motion estimation and motion compensation.
The VOP formed by the VOP formation unit 10 is inputted into a shape information coding unit 17, and then the shape information is coded.
Here, the output signal from the shape information coding unit 17 is determined based on the applicable field of the VOP coding unit. The output signal from the shape information coding unit 17 is inputted into the motion estimation unit 11, the motion compensation unit 12, and the video signal coding unit 14, respectively, and then is used for coding the internal information of the motion compensation and object.
In addition, the motion information estimated by the motion estimation unit 11, the internal information of an object coded by the video signal coding unit 14 and the shape information coded by the shape information coding unit 17 are multiplexed by a multiplexor 18, and then are transmitted in a bit stream through a buffer 19.
In the video coding unit for an MPEG-IV, a shape coding unit and a video object plane are used.
Here, the VOP denotes an object on a time-based axis of a content having a predetermined shape that a user can accesses and edit. The VOP is coded by the VOP for supporting a content-based functionality.
FIG. 2 illustrates a video formed of an object, which video is reconstructed by macro blocks formed of 16.times.16 pixels for a video coding.
When the block is thusly reconstructed into macro blocks, there exist three kinds of macro blocks as shown in FIG. 3. Namely, there are an intra-object macro block formed of an intra-object information, an extra-object not having an information of the object, and an object boundary macro block partially having an intra-object information.
FIG. 4 illustrates an arrangement of a luminance block and a color block. The intra-object macro block is formed of blocks of the object, and the extra-object macro block is formed of extra-object blocks.
However, in the object boundary macro block, there may exist three kinds of blocks each being formed of 8.times.8 pixels having the same characteristic as the macro block as shown in FIG. 5 such as an intra-object sub-block, an extra-object sub-block, and an object boundary sub-block.
FIG. 6 illustrates a conventional video signal coding unit 14 (VM5.0). In the coding unit 14, there are provided an extra-object region padding unit 14a for receiving an inter-video information or an original information from the motion compensation unit 12 and the VOP formation unit 10 as shown in FIG. 1 and a padding shape information (for example, an original video shape information and a recovered shape information) from the shape information coding unit 17 and padding the extra-object region, a DCT and coding unit 14b for DCT-coding the signal from the extra-object region padding unit 14a and outputting a signal information, and an IDCT and decoding unit 14c for IDCT-decoding the signal from the DCT and decoding unit 14b and outputting a decoded information to the previous VOP detection unit 16.
In order to decode the intra-video and inter-video information of the object boundary block, the pixel value of pixels in the extra-object region is first determined. Here, this intra-video signal (intra-texture data) and an error signal (residual texture data) are called a texture information.
Among the techniques, there are known a mean value replacement technique which is directed to filling a mean value of a video information into an object of a block, a zero padding technique which is directed to filling a zero value, a repetitive padding technique using an object boundary information, a shape adaptive DCT technique which does not care with respect to the extra-object information.
However, the intra-video and inter-video has a space surplus having a high relationship in the space. The recently introduced techniques are used by DCT-quantizing the space surplus in the block. However, these techniques do not use the space surplus between inter-blocks.
If the techniques use the space surplus existing between the blocks, it is possible to increase a coding efficiency.
When merging different video blocks padded in various padding techniques, a high frequency component may occur at the video boundary portion. Therefore, a proper padding technique which may increase a coding efficiency is needed.
The conventional padding techniques will be explained with reference to the conventional video signal coding unit 14 (VM5.0).
The mean value replacement technique is directed to filling the mean value of the intra-object pixel value of the intra-lock block in order to code the intra-video and inter-video information in the object boundary block of the object boundary macro block, and then the coding step is performed by using a DCT (Discrete Cosine Transform).
The mean value replacement technique is performed as shown in FIG. 7A. In the drawings, reference numeral 20 denotes a separator, 21 denotes a mean value calculator, and 22 denotes a selector.
The mean value "a" of the intra-object pixel in the object boundary block is computed, and the extra-object pixel value is replaced with "a", and then the coding step is performed by using the DCT.
Next, in the zero padding technique, the extra-object pixel value is filled with a zero value and then the coding step is performed by using a DCT in order to code the video information and an estimation error information in the object boundary block in the object boundary macro block.
In the zero padding technique, as shown in FIG. 7A, a white pixel which is an extra-object pixel in the object boundary block is replaced with a zero value, and then the coding step is performed by using the DCT. This technique is adapted for a coding step between inter-videos from 2.0 to 7.0 of the MPEG-IV VM vision.
In addition, the repetitive padding technique uses a reproduced shape information and includes five steps. Each step will now be explained with reference to FIG. 7B.
(1) The extra-object pixel value in the object boundary block is considered to have a zero value.
(2) The object boundary block is horizontally scanned. At this time, there may exist two kinds of horizontal lines.
Namely, there are a zero segment which is formed of zero value and a non-zero segment which is formed of non-zero value.
If there is a non-segment in the scanned horizontal line or there is only a non-zero segment, no step is performed. Thereafter, the horizontal line is scanned. If a zero segment exists between the block and the non-zero segment, the pixels of the zero segment is filled with an end pixel value of the non-zero segment which contacts with the zero segment. If the zero segment exists between the non-zero segments, the pixel is filled with a mean value of the end pixel value of the non-segment which contacts with the zero-segment.
(3) The object boundary block is scanned in the vertical direction, and then the steps of (2) are performed.
(4) If the extra-object pixels are filled in (2) and (3), the mean value between two values are filled thereinto.
(5) After the (1) through (4) are performed, the extra-object pixels which are not filled thereinto are horizontally scanned, and then the nearest pixel which does not have zero value is searched, and the distance is identical, the left-side pixel value which is not zero is fixed, and the steps are vertically performed. If the distance is identical, the upper-side pixel value which is not zero is fixed, and the mean value between two values is replaced with the value.
FIG. 7B illustrates a result of the above-described steps. The result is used for an intra-video and inter-video coding step in MPEG-IV VM1.0 and is used for the inter-video coding step of VM2.0 through 4.0.
In addition, the LPE(Low Pass Extrapolation) technique, as shown in FIG. 7C, includes a separator 20, a calculator 21, a selector 22, and a filter 23. A mean value of a video information in the block is obtained through the mean calculator 28 when the block to be coded is an object boundary block, and then the value "M" is filled into the pixels of the extra-object region, and the intra-object pixel values among the upper, lower, left-side and right-side pixels are added with respect to each pixel filled with the intra-object mean value are added, and the thusly added value is divided by the intra-object pixel number, and then the pixel value is replaced therewith.
For example, as shown in FIG. 7C, f1 is replaced with the lower-side intra-pixel value, f2 is replaced with a right-side intra-object pixel value, and f4 is replaced with a lower-side and right-side mean value.
In the LPE technique, in order code the video information of the object boundary block in the macro block, the extra-object pixel is filled with a mean value of the intra-block object pixel value in the block, and then the extra-object boundary pixels before the DCT step is filled with a mean value of the pixel values neighboring in four directions.
When there is an extra-object pixel in the pixels neighboring four-direction, the pixel value is excluded, and then the mean value of the intra-object pixel is obtained.
In addition, as shown in FIG. 7C, only the pixels between f1 through f9 become pixels which are replaced with the mean value of the intra-object pixel values neighboring in four-direction.
Thereafter, the DCT is used and codes the block. Currently, the LPE technique is adapted for performing the intra-video coding for the MPEG-IV VM5.0.
In addition, the DCT technique (SADCT: Shape Adaptive Discrete Cosine Transform Technique) is adapted to an object boundary block of a predetermined shaped VOP.
When a video coding step is performed based on a predetermined shaped VOP, differently from a method for replacing the pixel values which are not defined with respect to the extra-object pixel with a proper value, the coding step is performed through a coding and quantizing step by using only the intra-object information.
After the DCT is performed, the DCT coefficient has the same characteristic as the pixel number.
As shown in FIG. 7D, when the intra-object information such as "A" exists, the intra-video and inter-information is moved in the upper direction like "B", and then a one-dimensional DCT is performed in the vertical direction, and the DCT coefficient formed line "C" is moved in the left side direction line "D", and then a one-dimensional DCT is performed in the horizontal direction like "E".
After the step is performed with respect to "E", the SADCT coefficient is formed like "F", and the DCT coefficient after the SADCT is quantized, and a zig-zag scanning is performed with respect thereto. In addition, an adaptive scanning technique is performed with respect to the region in which a coefficient does not exist.
The coefficient values scanned along the adaptive scanning are coded by using the conventional VLC table and is adapted as a selection technique of an intra-video and inter-video coding in a range of MPEG-IV VM5.0 through VM7.0.
However, the above-described techniques has disadvantages in that a coding efficiency is significantly degraded because the space surplus which exists in the block is not used even when the space surplus in the block is properly used through the DCT and quantization.