KR20170095043A - Transcoding method and apparatus - Google Patents

Abstract

The present invention introduces a device for transcoding a first frame image with a first size into a second frame image with a second size. The device comprises: a decoding part performing decoding by receiving the first frame image; and an encoding part receiving intra and inter prediction information in decoding, and performing encoding into the second frame image. The encoding part encodes the second frame image based on a value calculated by applying a weight to at least one of (i) macroblock (MB) information and (ii) the intra or the inter prediction information of prediction block (PB) of the first frame image.

Description

[0001] TRANSCODING METHOD AND APPARATUS [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transcoding method and apparatus, and more particularly, to a data transcoding method and apparatus capable of transcoding a moving picture at an improved rate.

Transcoding is a technique used at the time of conversion from a specific codec to another codec, conversion of a frame rate, or size conversion of a frame.

The Moving Picture Experts Group (MPEG) provides codec technology in various formats. When video content (e.g., movie, sports, concert, etc.) compressed through a specific MPEG codec technology is to be transmitted to a receiver using different MPEG codec technology, the video content is decoded through the first compressed codec technique , It must undergo a transcoding process to encode it using another MPEG codec. For example, if a video content compression-encoded in MPEG-2 is to be transmitted in the MPEG-4 codec, it must be decoded through the MPEG-2 codec and then compression-encoded into the MPEG-4 codec.

Besides transcoding between codecs, transcoding exists for size conversion of input bit stream and output bit stream. Again, this may include a decoding and encoding process. This may be performed between the same codec or between different codecs.

However, in the case of transcoding for this size conversion, since the decoding of the input bit stream and the encoding of the output bit stream are performed separately, the intra / inter prediction part occupies a large amount of time and cost There is a problem that the efficiency of transcoding is lowered.

According to an exemplary embodiment of the present invention, there is provided a method of decoding a moving picture using a macroblock (MB) type and an intra / inter predicted value, which are known in the moving picture decoding process, And a transcoding method and apparatus capable of performing a transcoding.

According to an aspect of the present invention, there is provided an apparatus for transcoding a first frame image of a first size into a second frame image of a second size, the apparatus comprising: (I) macroblock (MB) information of the first frame image and (ii) a second frame image of the first frame image, wherein the encoding unit comprises: ii) encoding the second frame image based on a value calculated by applying a weight to at least one of intra or inter prediction information of a prediction block (PB).

The encoding unit may perform encoding by omitting a separate intra and inter prediction process based on the calculated value when encoding the prediction block of the second frame image.

The macroblock type of the second frame image may be determined based on a weighted average value of the type values of the macroblocks of the first frame image included in the macroblock of the second frame image.

The intra and inter prediction values of the prediction block of the second frame image may be determined based on the weighted average values of the intra and inter prediction values of the macro or prediction block of the first frame image included in the prediction block.

When the prediction block is encoded in the intra-prediction mode, a vector according to an intra-prediction mode of the prediction block includes a vector value having a direction according to a macro of the first frame image included in the prediction block, And calculating an area ratio value occupied by the macroblock or the prediction block of the first frame image within the prediction block.

When the prediction block is encoded in the inter-prediction mode, a motion vector (MV) of the prediction block is calculated based on a motion vector of a macroblock or a prediction block of the first frame image included in the prediction block, And calculating an area ratio value occupied by the macroblock or the prediction block of the first frame image.

Wherein when a macro or a prediction block of a first frame image included in the prediction block includes both an intra mode and an inter mode mode, The prediction mode having the higher weight can be used

The prediction block may be a macroblock.

According to an aspect of the present invention, there is provided a method of transcoding a first frame image of a first size into a second frame image of a second size, the decoding unit receiving the first frame image and performing decoding And performing encoding with the second frame image by receiving the intra and inter prediction information in the encoding unit decoding, wherein the encoding step comprises the steps of: (i) determining a macroblock (MB) of the first frame image; And (ii) encoding the second frame image based on a value calculated by applying a weight to at least one of intra or inter prediction information of a prediction block (PB).

The encoding step may include performing an encoding process by omitting a separate intra and inter prediction process based on the calculated value in encoding the prediction block of the second frame image.

The macroblock type of the second frame image may be determined based on a weighted average value of the type values of the macroblocks of the first frame image included in the macroblock of the second frame image.

When the prediction block is encoded in the intra-prediction mode, a vector according to an intra-prediction mode of the prediction block includes a vector value having a direction according to a macro of the first frame image included in the prediction block, And calculating an area ratio value occupied by the macroblock or the prediction block of the first frame image within the prediction block.

When the prediction block is encoded in the inter-prediction mode, a motion vector (MV) of the prediction block is calculated based on a motion vector of a macroblock or a prediction block of the first frame image included in the prediction block, And calculating an area ratio value occupied by the macroblock or the prediction block of the first frame image.

Wherein when a macro or a prediction block of a first frame image included in the prediction block includes both an intra mode and an inter mode mode, The prediction mode having the higher weight can be used

The prediction block may be a macroblock.

According to the transcoding method and apparatus according to an embodiment of the present invention, it is possible to reduce the time and cost of the intra / inter prediction part in the moving picture compressing process, which takes much time and cost of transcoding, It is effective.

1 is a block diagram schematically showing a configuration of a transcoding apparatus according to an embodiment of the present invention;
FIG. 2 is a detailed block diagram specifically illustrating a configuration of a decoding unit of a transcoding apparatus according to an embodiment of the present invention;
3 is a detailed block diagram specifically illustrating a configuration of an encoding unit of a transcoding apparatus according to an embodiment of the present invention,
4 is a conceptual diagram for explaining a block unit converted for transcoding for size conversion,
FIG. 5 is an enlarged view of the upper left block of FIG. 4,
6 is a diagram for explaining a macro block type,
7A and 7B are diagrams illustrating directional vectors according to various modes of intra prediction of a 4x4 block,
8A and 8B are diagrams illustrating directional vectors according to various modes of intra prediction of a 16x16 block.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

1 is a block diagram schematically showing a configuration of a transcoding apparatus according to an embodiment of the present invention. 1, a transcoding apparatus 100 according to an exemplary embodiment of the present invention may include a decoding unit 110 and an encoding unit 120. [

Referring to FIG. 1, a decoding unit 110 receives an image frame to be transcoded and decodes it according to a specific format. The decoding unit 110 may be configured to encode and decode the video data according to HEVC (High Efficiency Video Coding: H.265), AVC (Advanced Video Coding: H.264), H.263, H.262, H.261, MPEG- 4, WebM codec, VC-1, VP46, VP7, WMV, AMV, AVS, and the like. In this specification, H.264 / AVC is used as a reference. That is, in the embodiment of the present invention, the transcoding for size change is described as an example in the same codec standard, but the present invention is not limited thereto.

The decoding unit 110 may obtain intra and / or inter predicted values when decoding the input image. Decoding can be performed through intra / inter prediction and reconstruction of the residual value. The intra / inter prediction value can be transmitted to the encoding unit 120 for convenience of encoding. Although the decoded image frame bitstream and the intra / inter prediction information are separately transmitted, the decoded image frame bitstream and the intra / inter prediction information are not necessarily transmitted, but may be included in the decoded bitstream and transmitted to the encoding unit 120.

The encoding unit 120 may encode a specific format and a specific size based on the decoded bitstream frame. At this time, encoding can also perform encoding based on a number of standard techniques described above. In the present embodiment, prediction information upon decoding of H.264 / AVC is received and encoded in the H.264 / AVC format will be described as a reference. That is, the intra / inter prediction value and / or the macroblock related information for the H.264 / AVC is received from the decoding unit 110, and encoding can be performed in a desired format and / or size without performing a separate prediction process have. Particularly, when the size conversion is desired to convert to a size smaller than the original size, for example, when the size is changed from 1280 x 720 size to 720 x 480 size, the macroblock (and / or prediction block) A plurality of blocks may be included. Therefore, in this case, the type information of the macroblock before conversion and / or the prediction value of the prediction block can not be used as it is. In this case, the process of appropriately using macroblock type information and / or intra / inter predicted values will be described in detail.

In this specification, units and / or blocks refer to units of image encoding and decoding. The encoding or decoding unit in the image encoding and decoding means a divided unit when an image is divided and encoded or decoded. Therefore, a macro block (MB), a coding block (CB), a prediction block (PB) A prediction block, a transform block (TB), and the like. Also, in the embodiments described below, a block may also be referred to as a unit. One unit may be further subdivided into smaller units.

2 is a detailed block diagram specifically illustrating the configuration of a decoding unit of a transcoding apparatus according to an embodiment of the present invention. 2, the decoding unit 200 includes an entropy decoding unit 210, an inverse quantization unit 220, an inverse transform unit 230, an intra prediction unit 240, a motion compensation unit 250, (255), a filter unit (260), and a reference picture buffer (270).

The decoding unit 200 performs decoding in an intra mode or an inter mode and outputs a reconstructed image, that is, a reconstructed image. Intra prediction is intra prediction, and inter prediction is inter prediction. In the intra mode, the switch is switched to the intra mode, and in the inter mode, the switch can be switched to the inter mode. The decoding unit 200 may obtain a residual block from the input bitstream, generate a prediction block, and then add the residual block and the prediction block to generate a reconstructed block, that is, a reconstruction block.

The entropy decoding unit 210 may entropy-decode the input bitstream according to a probability distribution to generate symbols including a symbol of a quantized coefficient type. The entropy decoding method is similar to the entropy encoding method described above.

When the entropy decoding method is applied, a small number of bits are assigned to a symbol having a high probability of occurrence, and a large number of bits are assigned to a symbol having a low probability of occurrence, so that the size of a bit string for each symbol is Can be reduced. Therefore, the compression performance of the image decoding can be enhanced through the entropy decoding method.

The quantized coefficients are inversely quantized in the inverse quantization unit 220 and inversely transformed in the inverse transformation unit 230. As a result that the quantized coefficients are inversely quantized / inverse transformed, a residual block can be generated.

In the intra mode, the intraprediction unit 240 may generate a prediction block by performing spatial prediction using the pixel values of the already coded blocks around the current block. In this case, according to an embodiment of the present invention, the intraprediction unit 240 may separately transmit intraprediction information to the encoder so that the intraprediction information can be used in the prediction of the encoder.

In the inter mode, the motion compensation unit 250 can generate a prediction block by performing motion compensation using a motion vector (MV) and a reference image stored in the reference picture buffer 270. [ The motion compensation unit 250 may transmit the inter information including the motion vector information to the encoding unit.

The intra / intra prediction information thus transmitted may include information related to the type of macro block and / or prediction block.

The residual block and the prediction block are added through the adder 255, and the added block can be passed through the filter unit 260. [ The filter unit 260 may apply at least one of a deblocking filter, SAO, and ALF to a restoration block or a restored picture. The filter unit 260 may output a reconstructed image, that is, a reconstructed image. The restored image is stored in the reference picture buffer 270 and can be used for inter prediction.

3, the encoding unit 300 includes a motion predicting unit 311, a motion compensation unit 320, a motion compensation unit 320, A subtractor 325, a transformer 330, a quantizer 340, an entropy encoder 350, an inverse quantizer 360, an inverse transformer 360, An adding unit 370, an adder 375, a filter unit 380, and a reference picture buffer 390.

The encoding unit 300 encodes the input image decoded based on the intra / inter prediction information and the additional block related information transmitted from the decoding unit 200 in an intra mode or an inter mode, Can be output. At this time, the block size can be adjusted to be large or small by reflecting the converted frame size. To this end, a separate frame size converter (not shown) may be arranged.

In the intra mode, the switch 315 is switched to the intra mode, and in the inter mode, the switch 315 can be switched to the inter mode. The encoding unit 300 may generate a prediction block for an input block of the input image, and may then code the residual of the input block and the prediction block.

In the intra mode, the intraprediction unit 320 may generate a prediction block by performing spatial prediction using the pixel values of the already coded blocks around the current block. According to an embodiment of the present invention, the intraprediction unit 320 predicts a macro of a pre-conversion frame included in a corresponding block (e.g., a macroblock and / or a prediction block) through intra information provided from the decoding unit 200, It is possible to calculate an average value of a direction value of a vector according to an intra prediction of a block and / or a prediction block, thereby omitting the process of determining a prediction mode, etc. and performing intra prediction on the block based on the calculated average value have.

In the inter mode, the motion predicting unit 311 can find a motion vector by searching an area of the reference picture stored in the reference picture buffer 390 that is best matched with the input block. However, according to an embodiment of the present invention, the inter information (including the motion vector values of the respective prediction blocks (or macroblocks)) from the decoding unit 200 is transmitted to the motion compensation unit 312, The motion compensation may be performed based on the motion vector values of the pre-conversion prediction block and / or the macroblock included in the post-conversion macroblock without performing the motion prediction process of the motion vector prediction unit 311. Therefore, the motion prediction unit 311 may be omitted.

However, the motion vector value for inter prediction from the decoding unit 200 can not be directly applied to the motion compensation unit 312 of the encoding unit 300. The weight of the motion vector value from the decoding unit 200 The motion estimator 311 may calculate the average value and the motion estimator 311 may calculate the weighted average of the received motion vector values and transmit the calculated weighted average to the motion compensator 312. [ However, the calculation of the weighted average value may be performed directly by the motion compensation unit 312. [

In order to perform the intra / inter prediction in the encoding unit 300 using the intra / inter prediction information from the decoding unit 200, the encoding unit 300 determines a macroblock type of a specific block For this, the intra and / or inter prediction information from the decoding unit 200 may include the macroblock type information. Or the macroblock type information may be separately provided to the intra prediction unit 320 or the motion compensation unit 312. [

The motion compensation unit 312 can generate a prediction block by performing motion compensation using the motion vector thus obtained. Here, the motion vector is a two-dimensional vector used for inter prediction, and can represent an offset between the current image to be encoded / decoded and the reference image. Reference picture picture values and the like are included in the inter prediction information from the decoding unit and can be used as they are in encoding.

The subtractor 325 can generate a residual block by a difference between the input block and the generated prediction block. The transforming unit 330 may perform a transform on the residual block to output a transform coefficient. The quantization unit 340 may quantize the input transform coefficient according to the quantization parameter to output a quantized coefficient.

The entropy encoding unit 350 may perform entropy encoding based on the values calculated by the quantization unit 340 or the encoding parameter values calculated in the encoding process to output a bit stream.

When entropy encoding is applied, a small number of bits are allocated to a symbol having a high probability of occurrence, and a large number of bits are allocated to a symbol having a low probability of occurrence, thereby expressing symbols, The size of the column can be reduced. Therefore, the compression performance of the image encoding can be enhanced through the entropy encoding. The entropy encoding unit 350 may use an encoding method such as exponential golomb, Context-Adaptive Variable Length Coding (CAVLC), and Context-Adaptive Binary Arithmetic Coding (CABAC) for entropy encoding.

Since the encoding unit 300 according to the embodiment of FIG. 3 performs inter-prediction encoding, that is, inter-view prediction encoding, the currently encoded image needs to be decoded and stored for use as a reference image. Therefore, the quantized coefficients are inversely quantized in the inverse quantization unit 360 and inversely transformed in the inverse transformation unit 370. The inverse quantized and inverse transformed coefficients are added to the prediction block through an adder 375, and a reconstruction block is generated.

The restoration block passes through the filter unit 380 and the filter unit 380 applies at least one of a deblocking filter, a sample adaptive offset (SAO), and an adaptive loop filter (ALF) can do. The filter portion 380 may be referred to as an adaptive in-loop filter. The deblocking filter can remove block distortion occurring at the boundary between the blocks. The SAO may add a proper offset value to the pixel value to compensate for coding errors. ALF can perform filtering based on the comparison between the reconstructed image and the original image. The reconstruction block having passed through the filter unit 380 can be stored in the reference picture buffer 390. [

As described above with reference to FIGS. 2 and 3, the encoding unit 300 and the decoding unit 200 may perform intra prediction based on pixel information in the current picture to generate a prediction block. That is, the encoding unit 300 and the decoding unit 200 may perform directional prediction and / or non-directional prediction based on at least one reconstructed reference pixel. Here, the prediction block may refer to a block generated as a result of intra prediction. The prediction block may correspond to at least one of a macroblock (MB), a coding unit (CU), a prediction unit (PU), and a conversion unit (TU). The prediction block may be a square block having a size of 2x2, 4x4, 8x8, 16x16, 32x32 or 64x64, or may be a rectangular block having a size of 2x8, 4x8, 2x16, 4x16, have.

According to an embodiment of the present invention, the prediction block is an embodiment of H.264 / AVC, and 4x4 and / or 16x16 blocks are exemplified.

However, although the decoding unit 200 and the encoding unit 300 described above are described taking H.265 and / or H.264-based codec standards into account, they may be partially modified to be decoded and encoded according to each standard. Are obvious to a person skilled in the art.

4 is a conceptual diagram for explaining a block unit converted for transcoding for size conversion.

4, when transcoding is required to convert the image size of the moving image from the first size (original frame size) to the second size (output frame size), the first frame of the first size is converted into the second size And a plurality of first frame macroblocks may be included in the prediction block of the second frame (which may be a macroblock). In the embodiment of Fig. 4, the image indicated by the dotted line is the original image (the first frame) and the image indicated by the solid line is the image (the second frame) whose size is reduced (transcoded). In particular, according to the embodiment of FIG. 4, the second frame macroblock 410 also includes a 16x16 macroblock 420 of the first frame and a 4x4 macroblock 430 of the first frame.

According to an exemplary embodiment of the present invention, a macroblock type (type) of a reduced-size second frame of a macroblock 410 is a weight of a macroblock type of the pre-conversion macroblocks 420 and 430 included therein Can be determined as an average value. This will be described in more detail with reference to FIG. 5 below.

5 is an enlarged view of the upper left block in Fig.

Referring to FIG. 5, a prediction block 510 (which may be a macroblock) of a second frame includes therein 16x16 macroblocks 520, 522, and 524 of a plurality of first frames and 4x4 Macroblocks 526, 528, 530, and 532 of FIG. At this time, the macroblock type of the prediction block 510 of the second frame may be determined as a weighted average of the macroblocks 520, 522, 524, 526, 528, 530, and 532 of the first frame before the conversion. This will be described with reference to FIG.

Determine macroblock type

6 is a diagram for explaining a macroblock type. This is an embodiment of H.264 / AVC, but not necessarily limited thereto.

Referring to FIG. 6, macroblock types may exist in 16x16, 16x8, 8x16, and 8x8. In the case of 8x8, it can be divided into 8x8, 4x8, 8x4, and 4x4 types as sub macro block types.

In the case of motion compensation using inter prediction, the current block can be predicted by estimating the motion from the previously encoded frame. In this case, when the size of the block for motion compensation is larger than 8x8 pixels, the reference picture number and the motion vector And can be encoded for each motion compensation block. According to an embodiment of the present invention, the inter-prediction information from the decoding unit may include a size (type information) of a macroblock, information for identifying inter prediction, and / or motion vector information. At this time, when the size of the motion compensation block is smaller than 8x8 pixels, the block type is displayed first in the sub MB type, and encoding can be performed for each sub macro block. According to this principle, in the case of inter prediction, the decoding unit encodes macroblock type information into one of 16x16, 16x8, and 8x16 when the macroblock type information is larger than 8x8. When the macroblock type information is smaller than 8x8, the macroblock type is 8x8, 4x8, 8x4, and 4x4, so that the type of the corresponding macroblock can be grasped.

Also, in the case of intra prediction, the intra prediction information from the decoding unit may include information on intra-picture prediction of a 16x16 macroblock or intra-picture prediction of a 4x4 macroblock.

As described above, the intra and / or inter information may include macroblock type information of the first frame before conversion. Alternatively, macroblock type information provided separately may be used.

5, the encoding unit may change the type of the macroblock 510 in the second frame after the conversion to the weight of the macroblocks 520, 522, 524, 526, 528, 530, and 532 in the first frame And in this case, the area ratio of each macroblock can be used as a weight. That is, the weight value w ₁ can be determined as the area ratio occupied by the macroblock 520 in the entire macroblock 510 in the macroblock 520. Because the macroblock 522 is different from the 16x16 macroblock such as the macroblock 520 or the area occupied in the macroblock 510 (because a part thereof is cut off), the weight value (w ₂ ) can be determined. The macroblock 526 may be a 4x4 macroblock having a small size and a weight value w ₄ corresponding to the area. The weight value according to the area ratio can be used not only for mode determination in intra prediction but also for motion vector determination in inter mode.

The weight values of the respective macroblocks are multiplied by the type information values to add the products of the weights of all the macroblocks to the type information values, and then the values are averaged to determine the type of the macroblock.

Alternatively, if the sum of the weight values of the macroblocks indicating the same type indicates a specific threshold value or more, the type can be set as the macroblock type of the second frame after conversion. That is, for example, a specific macroblock type in which the sum of weight values exceeds a majority can be set as the macroblock type of the second frame as it is.

The setting for the mechanism for this type determination can be set through user setting, and may be changed later.

Intra prediction

Hereinafter, a case in which intra prediction is performed according to intra prediction information from a decoding unit will be described in detail.

FIGS. 7A and 7B are diagrams showing directional vectors according to various modes of intra prediction of a 4x4 block. FIG.

Referring to FIGS. 7A and 7B, it is assumed that H.264 / AVC is decoded according to an embodiment of the present invention, transcoding is required by encoding H.264 / AVC and reducing the size. In the case of the intra-prediction mode in the encoding unit, as shown in FIGS. 7A and 7B, it can be recognized as a vector having a directivity for each prediction mode. That is, the prediction mode 0 is a vertically descending vector, and the 1 can be recognized as a vector having a directionality such as a vector extending horizontally from left to right. At this time, the amount of scalar may be the same although only the direction of the vector is different.

In the embodiment of the present invention, when a predicted block to be encoded is to be intra-coded, a ratio of a directional vector according to an intra mode of a first frame of macroblocks included in a specific predictive block after the conversion, The directionality of the prediction mode can be determined.

That is, the predicted value can be calculated through the following equation.

은 변환된 제 2 프레임에서의 인트라 예측값 벡터를 나타내고,

는 변환 전 원본 프레임, 즉 제 1 프레임에서의 인트라 예측값 벡터를 나타낸다. w_n은 제 1 프레임에서의 해당 매크로블록의 면적에 따른 가중치 값을 나타낸다(도 5 참조).

Denotes an intra-prediction-value vector in the transformed second frame,

Represents an intraprediction vector in the original frame before the conversion, i.e., the first frame. w _n denotes a weight value according to the area of the corresponding macroblock in the first frame (see FIG. 5).

The predicted value vector thus calculated may not exactly match the mode according to FIGS. 7A and 7B. These vector values can be used as they are.

Alternatively, an approximate value may be applied to a prediction mode which is most similar (or most similar) to the vector value calculated in some cases.

According to another embodiment of the present invention, in the case of the prediction mode 2 (mean value prediction), since there is no directional vector, even if only one other mode exists, it can not be adopted. That is, it is highly likely to be excluded from normal calculations. Thus, if there is a macroblock having a prediction ratio of 2 or more and a prediction value of 2 or more, the second prediction block may be determined as the prediction mode 2.

8A and 8B are diagrams illustrating directional vectors according to various modes of intra prediction of a 16x16 block. 8A and 8B show examples of the vertical prediction, the horizontal prediction, the average value prediction, and the plane prediction as the intra prediction modes of 16x16 blocks. 8A shows a latitude signal prediction mode of a 16x16 block, and FIG. 8B shows a prediction of a color difference signal. In the case of a color difference signal, an 8x8 pixel unit can be used.

According to FIGS. 8A and 8B, since the horizontal and vertical prediction modes have directional vectors, they can be expressed as directional vectors, and predicted values can be calculated as average values according to weights.

However, since it is difficult to represent a directional vector as a directional vector in the case of the prediction mode 2 (average value prediction) and the prediction mode 3 (planar prediction), it is also difficult to express the directional vector based on the weighting factor If the threshold value is exceeded, the prediction mode of the prediction block of the second frame can be determined in the prediction mode.

For example, when the area ratio of the prediction mode 0 is 10%, the area ratio of the prediction mode 1 is 20%, the area ratio of the prediction mode 2 is 60%, and the area ratio of the prediction mode 3 is 10% And the prediction mode 2 having a weight value exceeding 50% can be determined as the prediction mode of the corresponding prediction block of the second frame.

Or a prediction mode having a weight according to the highest area ratio without a threshold value may be determined as a prediction mode of the prediction block.

Inter prediction

Hereinafter, a method of performing inter prediction in the encoding unit using inter prediction information from the decoding unit in inter prediction will be described in detail.

In the case of inter prediction, a predicted value can be obtained by the following equation.

는 변환된 제 2 프레임에서의 모션 벡터를 나타내고,

는 변환 전 원본 프레임, 즉 제 1 프레임에서의 모션 벡터를 나타낸다. w_n은 제 1 프레임에서의 해당 매크로블록의 면적에 따른 가중치 값을 나타낸다(도 5 참조). 이때, 모션 벡터에서는 벡터 방향 값뿐만 아니라 스칼라량도 서로 다를 수 있고, 양 부분이 모두 고려될 수 있다.here,

Represents the motion vector in the transformed second frame,

Represents the original frame before the conversion, i.e., the motion vector in the first frame. w _n denotes a weight value according to the area of the corresponding macroblock in the first frame (see FIG. 5). At this time, not only the vector direction value but also the scalar amount may be different from each other in the motion vector, and both parts can be considered.

According to the embodiment of the present invention, when intra-predicted macroblocks and inter-predicted macroblocks co-exist in a specific predictive block of the second frame, a higher-weighted prediction mode can be used. That is, if the area ratio of the intra-predicted block is 47% and the area ratio of the inter-predicted block is 53%, the prediction is performed in the inter-prediction mode. At this time, based on the motion vector information from the decoding unit, The motion vector value of the prediction block of the second frame can be determined as an average value obtained by multiplying each motion vector value of the macro block of the frame by a weight according to the area.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions as defined by the following claims It will be understood that various modifications and changes may be made thereto without departing from the spirit and scope of the invention.

Claims (16)

An apparatus for transcoding a first frame image of a first size into a second frame image of a second size,
A decoder receiving the first frame image and performing decoding; And
And an encoding unit receiving the intra and inter prediction information upon decoding and performing encoding into the second frame image,
The encoding unit may calculate a value calculated by applying a weight to at least one of (i) macroblock information of the first frame image and (ii) intra or inter prediction information of a prediction block (PB) And encodes the second frame image based on the second frame image. The method according to claim 1,
Wherein the encoding unit performs encoding by omitting a separate intra and inter prediction process based on the calculated value when encoding the prediction block of the second frame image. The method according to claim 1,
Wherein the macroblock type of the second frame image is determined based on a weighted average value of the type values of the macroblocks of the first frame image included in the macroblock of the second frame image. The method according to claim 1,
Wherein intra and inter prediction values of a prediction block of the second frame image are determined based on weighted average values of intra and inter prediction values of a macro or prediction block of a first frame image included in the prediction block. 5. The method of claim 4,
When the prediction block is encoded in the intra prediction mode, the vector according to the intra prediction mode of the prediction block is:
A vector value having a directionality according to a macro of the first frame image included in the prediction block or an intra prediction mode of the prediction block; And
And calculating an area ratio value occupied by the macroblock or the prediction block of the first frame image in the prediction block. 5. The method of claim 4,
When the prediction block is encoded in the inter prediction mode, the motion vector (MV) of the prediction block is:
A motion vector value of a macro or prediction block of the first frame image included in the prediction block; And
And calculating an area ratio value occupied by the macroblock or the prediction block of the first frame image in the prediction block. 5. The method of claim 4,
When a macro or a prediction block of the first frame image included in the prediction block includes both the intra mode and the inter mode,
Wherein a prediction mode having a higher weight according to an area ratio occupied by macros or prediction blocks of the first frame image in the prediction block is used. The method according to claim 1,
Wherein the prediction block is a macroblock. A method for transcoding a first frame image of a first size into a second frame image of a second size,
The decoding unit receiving the first frame image and performing decoding; And
And performing encoding with the second frame image by receiving the intra and inter prediction information in decoding by the encoding unit,
Wherein the encoding step comprises the step of: applying a weight to at least one of (i) macroblock (MB) information of the first frame image and (ii) intra or inter prediction information of a prediction block (PB) And encoding the second frame image based on the second frame image. 10. The method of claim 9,
Wherein the encoding step includes the step of omitting a separate intra and inter prediction process based on the calculated value when encoding the prediction block of the second frame image and performing encoding. 10. The method of claim 9,
Wherein the macroblock type of the second frame image is determined based on a weighted average value of the type values of the macroblocks of the first frame image included in the macroblock of the second frame image. 10. The method of claim 9,
Wherein intra and inter prediction values of a prediction block of the second frame image are determined based on a weighted average value of intra and inter prediction values of macros or prediction blocks of a first frame image included in the prediction block. 13. The method of claim 12,
When the prediction block is encoded in the intra prediction mode, the vector according to the intra prediction mode of the prediction block is:
A vector value having a directionality according to a macro of the first frame image included in the prediction block or an intra prediction mode of the prediction block; And
And calculating an area ratio value occupied by the macroblock or the prediction block of the first frame image in the prediction block. 13. The method of claim 12,
When the prediction block is encoded in the inter prediction mode, the motion vector (MV) of the prediction block is:
A motion vector value of a macro or prediction block of the first frame image included in the prediction block; And
And calculating an area ratio value occupied by the macroblock or the prediction block of the first frame image in the prediction block. 13. The method of claim 12,
When a macro or a prediction block of the first frame image included in the prediction block includes both the intra mode and the inter mode,
Wherein a prediction mode having a higher weight according to an area ratio occupied by macros or prediction blocks of the first frame image in the prediction block is used. 10. The method of claim 9,
Wherein the prediction block is a macroblock.

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