Technical Field】
The present invention relates to a video encoding and decoding method, and
more specifically, the present invention pertains to a method for deriving a
temporal prediction motion vector and an apparatus for using this method.
【Background Art】
In recent years, a demand for high-resolution, high-quality video, such as
HD (High Definition) video and UHD (Ultra High Definition) video, has been
increased in various areas. As video data comes to have high resolution and/or
high quality, an amount of video data relatively goes up compared with existing
video data, and thus, when the video data is transmitted via a conventional
wired/wireless broadband network or is stored in an existing storage medium, costs
for transmission and storage are increased. To address such problems that occur
as video data goes to high resolution and high quality, high-efficiency video
compression technologies may be utilized.
A number of scheme have been introduced for a video compression, such as
inter prediction scheme that predicts pixel values included in a current picture from
a picture before or after the current picture, intra prediction scheme that predicts
pixel values included in a current picture using pixel information in the current
picture, and entropy encoding scheme that assigns a shorter codeword to a value
that happens more frequently while assigning a longer codeword to a value that
happens less frequently. Such video compression schemes may be utilized to
effectively compress, transmit, or store video data.
【Summary of Invention】
【Technical Problem】
An object of the present invention is to provide a method of deriving a
temporal prediction motion vector for a block adjoining with an LCU boundary.
Another object of the present invention is to provide an apparatus of
performing a method of deriving a temporal prediction motion vector for a block
adjoining with an LCU boundary.
【Technical Solution】
To achieve the first object of the present invention, according to an aspect
of the present invention, a video decoding method includes the steps of
3
determining a reference picture index of a collocated block of a prediction target
block; and determining a motion prediction vector of the collocated block, the
collocated block is a block adaptively determined by a location of the prediction
target block within a Largest Coding Unit (LCU). The collocated block may be
differently determined by deciding whether a lower boundary of the prediction
target block adjoins with an LCU boundary. The collocated block may be
differently determined by deciding whether a lower boundary of the prediction
target block adjoins with an LCU boundary and whether only a right boundary of
the prediction target block adjoins with the LCU boundary. The collocated block
may be determined by referencing positions of pixels within the LCU. If a left
side or lower boundary of the prediction target block does not adjoin with the LCU
boundary, a first collocated block and a fifth collocated block are sequentially
determined as the collocated block according to an availability of the collocated
block at a corresponding position.
To achieve the second object of the present invention, according to an
aspect of the present invention, a video decoding method may include the steps of
determining whether a boundary of a prediction target block adjoins with a
boundary of a LCU; and determining an availability of a first collocated block
according to the determination of whether the boundary of the prediction target
block adjoins with the boundary of the LCU. The video decoding method may
further include the step of determining other collocated block except for the first
collocated block as a collocated block to derive a temporal prediction motion
vector if it is determined that the first collocated block is not available. The step
of determining the other collocated block except for the first collocated block as
the collocated block to derive the temporal prediction motion vector if the first
collocated block is not available, is a step for determining different collocated
blocks to derive the temporal prediction motion vector for a case where a lower
boundary of the prediction target block adjoins with the boundary of the LCU and
for a case where only a right boundary of the prediction target block adjoins with
the boundary of the LCU. The step of determining the availability of the first
collocated block according to the determination of whether the boundary of the
prediction target block is adjoined with the boundary of the LCU, is a step for
determining the first collocated block as unavailable if a lower boundary of the
prediction target block adjoins with the boundary of the LCU. The step of
determining the first collocated block as the collocated block to derive the
temporal prediction motion vector if the first collocated block is available, or
determining an availability of a fifth collocated block if the first collocated block is
not available, may be further comprised.
To achieve the third object of the present invention, according to an aspect
of the present invention, a video decoding apparatus includes an entropy decoding
4
unit that decodes LCU size information and a prediction unit that determines a
reference picture index of a collocated block of a prediction target block and
determines a motion prediction vector of the collocated block, wherein the
collocated block is a block adaptively determined by a location of the prediction
target block within an LCU. The collocated block may be differently determined
by deciding whether a lower boundary of the prediction target block adjoins with
an LCU boundary. The collocated block may be differently determined by
deciding whether a lower boundary of the prediction target block adjoins with an
LCU boundary and whether only a right boundary of the prediction target block
adjoins with the LCU boundary. The collocated block may be determined by
referencing positions of pixels within the LCU. If a left side or lower boundary
of the prediction target block is not adjoined with the LCU boundary, a first
collocated block and a fifth collocated block are sequentially determined as the
collocated block according to an availability of the collocated block at a
corresponding position.
To achieve the fourth object of the present invention, according to an aspect
of the present invention, a video decoding unit may include an entropy decoding
unit that decodes LCU size information and a prediction unit that determines
whether a boundary of a prediction target block adjoins with a boundary of an
LCU and determines an availability of a first collocated block according to the
determination of whether the boundary of the prediction target block adjoins with
the boundary of the LCU. The prediction unit may determine other collocated
block except for the first collocated block as a collocated block to derive a
temporal prediction motion vector if it is determined that the first collocated block
is not available. The prediction unit may determine different collocated blocks to
derive the temporal prediction motion vector for a case where a lower boundary of
the prediction target block adjoins with the boundary of the LCU and for a case
where only a right boundary of the prediction target block adjoins with the
boundary of the LCU. The prediction unit may determine the first collocated
block as unavailable if a lower boundary of the prediction target block adjoins with
the boundary of the LCU. The prediction unit may determine the first collocated
block as the collocated block to derive the temporal prediction motion vector if the
first collocated block is available, or may determine an availability of a fifth
collocated block if the first collocated block is not available.
【Advantageous Effects】
As described above, the method of deriving a temporal prediction motion
vector and an apparatus of using the method according to an embodiment of the
present invention may differently use a collocated (or co-located or colocated)
picture, from which a temporal motion vector derived, depending on whether a
5
prediction target block adjoins an LCU. By using this method, the bandwidth of
memory unnecessarily used to derive a temporal motion vector may be reduced
and complexity in implementation may be minimized.
【Description of Drawings】
Fig. 1 is a block diagram illustrating a video encoding apparatus according
to an embodiment of the present invention.
Fig. 2 is a block diagram illustrating a video decoder according to another
embodiment of the present invention.
Fig. 3 is a conceptual view illustrating a method of deriving a temporal
prediction motion vector according to an embodiment of the present invention.
Fig. 4 is a flowchart illustrating a method of deriving a temporal prediction
motion vector according to an embodiment of the present invention.
Fig. 5 is a conceptual view illustrating a position of a collocated block to
derive a temporal motion vector according to an embodiment of the present
invention.
Fig. 6 is a conceptual view illustrating a method of determining a collocated
block to derive a motion prediction vector according to an embodiment of the
present invention.
Fig. 7 is a conceptual view illustrating a case where a prediction target
block adjoins with a lower boundary of an LCU according to an embodiment of the
present invention.
Fig. 8 is a flowchart illustrating an inter prediction method using a merge
mode according to an embodiment of the present invention.
Fig. 9 is a conceptual view illustrating locations of spatial merging
candidates according to an embodiment of the present invention.
Fig. 10 is a flowchart illustrating an inter prediction method using AMVP
according to an embodiment of the present invention.
【Mode for Invention】
Various modifications may be made to the present invention and the present
invention may have a number of embodiments. Specific embodiments are
described in detail with reference to the figures. However, the present invention
is not limited to specific embodiments, and it should be understood that the present
invention includes all modifications, equivalents, or replacements that are included
in the spirit and technical scope of the present invention. Similar referencing
marks may be used for between similar modules when the figures are explained.
The terms “first” and “second” may be used to describe various components
(or feature). However the components are not limited thereto. These terms are
6
used only to distinguish one component from another. For example, the first
component may be also named as the second component, and the second
component may be similarly named as the first component. The term “and/or”
includes a combination of a plurality of related items as described herein or any
one of the plurality of related items.
When a component (or feature) is “connected” or “coupled” to another
component, the component may be directly connected or coupled to the other
component. In contrast, when a component is “directly connected or coupled” to
another component, no component intervenes.
The terms used herein are given to describe the embodiments but not
intended to limit the present invention. A singular term includes a plural term
unless otherwise stated clearly in context. As used herein, the terms “include” or
“have”, etc. are used to indicate that there are features, numerals, steps, operations,
components, parts or combinations thereof as described herein, but do not exclude
the presence or possibility of addition of one or more features, numerals, steps,
operations, components, parts or components thereof.
Hereinafter, preferred embodiments of the present invention will be
described in greater detail with reference to the accompanying drawings. The
same reference numerals refer to the same components throughout the drawings,
and the description of the same components is not repeated.
Fig. 1 is a block diagram illustrating a video encoding apparatus according
to an embodiment of the present invention.
Referring to Fig. 1, the video encoding apparatus 100 may include a picture
splitting module 110, an inter prediction module 120, an intra prediction module
125, a transform module 130, a quantization module 135, a re-arrangement module
160, an entropy encoding module 165, a dequantization module 140, an inverse
transform module 145, a filtering module 150, and a memory 155.
Each module of Fig. 1 are shown independently from each other to
represent different functions from each other in the video encoding apparatus, but
this does not mean that each module should be implemented in a separated
hardware or software module (component) unit. That is, for convenience of
description, the modules are shown to be provided independently, and at least two
of the modules may be combined to constitute one module, or one of the modules
may be divided into a plurality of modules to perform functions. Embodiments of
combinations of the modules or embodiments of separation of the modules are also
included in the scope of the present invention without departing from the gist of
the present invention.
Further, some of the modules may be not essential modules that perform
essential functions of the present invention but may be rather optional modules to
7
enhance performance. The present invention may include only the essential
modules necessary to implement the gist of the present invention excluding the
modules merely used for better performance, and this structure is also included in
the scope of the present invention.
A picture splitting module 110 may split an input picture into at least one
processing unit. At this time, the processing unit may be a prediction unit (PU), a
transform unit (TU), or a coding unit (CU). The picture splitting module 110 may
encode the picture by splitting one picture into a combination of a plurality of
coding units, prediction units, and transform units, and a combination of one
coding unit, prediction unit and transform unit may be selected according to a
predetermined standard (or reference) such as a cost function and may be encoded.
For example, one picture may be split into a plurality of coding units. A
recursive tree structure, such as quad tree structure, may be used to split a picture
into coding units. With a picture or a largest coding unit as a root, a coding unit
may be split into other coding units as many child nodes as the number of the split
coding units. The coding unit that is no more split due to a predetermined
limitation is to be a leaf node. That is, assuming that only square-shape split is
available for a coding unit, the coding unit may be split into a maximum of four
other coding units.
Hereinafter, in embodiments of the present invention, the coding unit may
mean a unit in which decoding as well as encoding is performed.
A prediction unit may be partitioned with a form of at least one square or
rectangle having a same size within a coding unit.
Upon generation of a prediction unit in which intra prediction is performed
based on a coding unit, if the coding unit is not a smallest coding unit, intra
prediction may be performed without splitting the prediction unit into a plurality of
NxN prediction units.
A prediction module may include an inter prediction module 120 that
performs an inter prediction and an intra prediction module 125 that performs an
intra prediction. It may be determined whether to perform the inter prediction or
intra prediction with respect to the prediction unit, and according to each prediction
method, specific information (e.g., intra prediction mode, motion vector, reference
picture, etc.) may be determined. At this time, a processing unit on which
prediction is performed may differ from a processing unit on which the prediction
method and its details are determined. For example, the prediction method and
prediction mode may be determined by a prediction unit, and a performance of the
prediction may be performed in a transform unit. A residual value (residual
block) between a generated prediction block and an original block may be input to
the transform module 130. Further, the prediction mode information and motion
vector information, etc. used for the prediction, together with the residual value,
8
may be encoded in an entropy encoding module 165 and may be then transmitted
to a decoding apparatus. If a specific encoding mode is used, rather than
generating the prediction block by the prediction module 120 and 125, the original
block, as is, may be encoded and transmitted to the decoding apparatus.
The inter prediction module may predict a prediction unit based on
information of at least one picture among pictures prior to a current picture or
pictures after the current picture. The inter prediction module may include a
reference picture interpolation module, a motion prediction module, and a motion
compensation module.
The reference picture interpolation module may receive reference picture
information from the memory 155 and may generate pixel information in the unit
of less than an integer pixel unit within the reference picture. In the case of luma
pixels, a DCT-based 8 tap interpolation filter with different filter coefficients for
each tap may be used to generate the pixel information in the unit of less than the
integer pixel unit, a unit of 1/4 pixel. In the case of a chroma signal, a DCT-based
4 tap interpolation filter with different filter coefficients for each tap may be used
to generate the pixel information in the unit of less than the integer pixel unit, a
unit of 1/8 pixel.
A motion prediction module may perform motion prediction based on a
reference picture interpolated by the reference picture interpolation module. To
derive a motion vector, various methods may be used, such as FBMA (Full searchbased
Block Matching Algorithm), TSS (Three Step Search), NTS (New Three-
Step Search Algorithm), etc. The motion vector may have a motion vector value
in a 1/2 pixel unit or in a 1/4 pixel unit based on an interpolated pixel. The
motion prediction module may predict a current prediction unit by applying
various motion prediction method. As to the motion prediction method, various
methods may be used, such as a skip method, a merge method, or an AMVP
(Advanced Motion Vector Prediction) method.
According to an embodiment of the present invention, the inter prediction
module may determine whether a boundary of a prediction target block adjoins
with a boundary of an LCU (Largest Coding Unit), and may determine whether a
first collocated (or colocated or co-located) block is available according to the
determination of whether the boundary of the prediction target block adjoins with
the boundary of the LCU. For example, in case the first collocated block is not
available, a second collocated block may be determined as a collocated block to
derive a temporal prediction motion vector. Or in case the first collocated block
is not available, a position of the first collocated block may be changed, and the
position-changed first collocated block may be determined as a collocated block to
derive a temporal prediction motion vector.
Further, the inter prediction module may include a predicting module that
9
determines a reference picture index of a collocated block of a prediction target
block and determines a motion prediction vector of the collocated block. The
collocated block may be adaptively determined according to a location of the
prediction target block in the LCU (Largest Coding Unit). Hereinafter, the
operation of the prediction module according to the present invention is described
in detail.
The inter prediction module may generate a prediction unit based on
information on a reference pixel neighboring to the current block, which is pixel
information on pixels in the current picture. In case the block neighboring to the
current prediction unit is a block that inter prediction is applied to, and thus, the
reference pixel is a pixel through the inter prediction, the reference pixel included
in the block to which the inter prediction applied may be replaced with reference
pixel information of a block to which the intra prediction applied. That is, in case
a reference pixel is not available, the unavailable reference pixel information may
be replaced with at least one of available reference pixels.
As for the intra prediction, prediction modes may include a directional
prediction mode in which reference pixel information is used according to a
prediction direction and a non-directional mode in which, upon prediction, no
directional information is used. A mode for predicting luma information may be
different from a mode for predicting chroma information. Further, information on
an intra prediction mode in which luma information has been predicted or
predicted luma signal information may be utilized in order to predict chroma
information.
Upon performing the intra prediction, if the size of a prediction unit is the
same as the size of a transform unit, the intra prediction is performed based on
pixels located at the left side of the prediction unit, a pixel located at a top left of
the prediction unit, and pixels located at top on the prediction unit. However,
upon performing intra prediction, if the size of the prediction unit is different from
the size of the transform unit, the intra prediction may be performed by using
reference pixels based on the transform unit. Further, for a smallest coding unit
only, the intra prediction may be performed by using NxN partition.
In the intra prediction method, a prediction block may be generated after
being applied with an MDIS (Mode Dependent Intra Smoothing) filter on reference
pixels according to the prediction mode. Various types of AIS filters may be
applicable to the reference pixels. To perform the intra prediction method, an
intra prediction mode of a current prediction unit may be predicted from an intra
prediction mode of a neighboring prediction unit of the current prediction unit. In
case the prediction mode of the current prediction unit is predicted using the mode
information predicted from the neighboring prediction unit, if the intra prediction
mode of the current prediction unit is the same as the intra prediction mode of the
10
neighboring prediction unit, predetermined flag information may be used to
transmit information indicating that the current prediction unit is identical in the
prediction mode to the neighboring prediction unit. And if the prediction mode of
the current prediction unit is different from the prediction mode of the neighboring
prediction unit, an entropy encoding may be performed to encode the prediction
mode information of the current block.
Further, a residual block may be derived, which includes information on a
residual value that is a differential value between an original block of a prediction
unit and a prediction unit on which prediction is performed based on the prediction
unit generated in the prediction module 120 and 125. The derived residual block
may be input to the transform module 130. The transform module 130 may
transform the residual block by a transform method, such as DCT (Discrete Cosine
Transform) or DST (Discrete Sine Transform). The residual block includes
residual information between the prediction unit generated through the prediction
module 120 and 125 and the original block. Whether to apply DCT or DST to
transform the residual block may be determined based on intra prediction mode
information of the prediction unit used for generating the residual block.
The quantization module 135 may quantize values transformed into a
frequency domain by the transform module 130. A quantization parameter may
vary depending on a block or importance of an image. A value produced from the
quantization module 135 may be provided to the dequantization module 140 and
the re-arrangement module 160.
The re-arrangement module 160 may perform re-arrangement of
coefficients for the quantized residual value.
The re-arrangement module 160 may change 2-dimensional (2D) block
shaped coefficients to one-dimensional vector form through a coefficient scanning
method. For example, the re-arrangement module 160 may use a diagonal
scanning method for scanning from DC coefficients to high-frequency coefficients,
thereby arranging 2D block shaped coefficients into the form of a one-dimensional
vector. Depending on the size of the transform unit and intra prediction mode,
instead of the diagonal scanning method, a vertical scanning method in which 2D
block shaped coefficients are scanned along a column direction or a horizontal
scanning method in which 2D block shaped coefficients are scanned along a row
direction may be used. In other words, one of the diagonal scanning, vertical
scanning, and horizontal scanning may be used depending on the size of the
transform unit and the intra prediction mode.
The entropy encoding module 165 may perform an entropy encoding based
on values produced by the re-arrangement module 160. For the entropy encoding,
various encoding methods, such as, e.g., Exponential Golomb, CABAC (Context-
Adaptive Binary Arithmetic Coding), may be applied.
11
The entropy encoding module 165 may encode various information, such as
residual coefficient information and block type information of the coding unit,
prediction mode information, partition unit information, prediction unit
information and transmission unit information, motion vector information,
reference frame information, interpolation information for a block, filtering
information, and LCU size information, which are provided by the re-arrange
module 160 and the prediction module 120 and 125.
The entropy encoding module 165 may perform an entropy encoding on the
coefficient values of the coding unit as an input from the re-arrangement module
160 by using an entropy encoding method, such as CABAC.
The dequantization module 140 may perform dequantization on the values
quantized by the quantization module 135, and the inverse transform module 145
may perform inverse transform on the values transformed by the transform module
130. The residual values generated by the dequantization module 140 and the
inverse transform module 145 may be added with the prediction unit predicted
through a motion estimation module, a motion compensation module and an intra
prediction module included in the prediction module 120 and 125, thereby
generating a restored block.
A filtering module 150 may include at least one of a deblocking filter, an
offset correcting module, and an ALF (Adaptive Loop Filter).
A deblocking filter may remove a block distortion that is occurred due to a
block boundary in the restored (or reconstructed) picture. Whether to apply the
deblocking filter to a current block may be determined by a pixel included in
several rows or columns included in blocks. In case that the deblocking filter is
applied to the block, either a strong filter or a weak filter may be applied according
to a necessary strength of the deblocking filtering. Further, in case that the
deblocking filter is applied to the block, a horizontal direction filtering and a
vertical direction filtering may be performed in parallel.
An offset correcting module may correct an offset between an original
picture and a picture applied with deblocking in a pixel unit (or a per-pixel basis).
In order to perform the offset correction on a specific picture, pixels included in the
picture are partitioned into a predetermined number of areas, one of which is then
determined to perform an offset, and a method of applying an offset to the
corresponding area or a method of applying an offset considering edge information
of each pixel may be used.
An ALF (Adaptive Loop Filter) may perform a filtering based on a value
obtained by comparing a filtered reconstructed (or restored) picture with the
original picture. Pixels included in a picture are partitioned into predetermined
groups, and then, one filter to be applied to a corresponding group is determined to
thereby perform filtering on each group in a discriminating way. With respect to
12
information on whether to apply the ALF, a luma signal may be transmitted for
each coding unit, and the size and coefficient of the ALF to be applied may vary
for each block. The ALF may have various shapes, and the number of
coefficients included in the filter may vary correspondingly. Filtering-related
information of such ALF (e.g., filter coefficient information, ALF On/Off
information, or filter shape information) may be transmitted, included in a
predetermined parameter set of the bitstream.
The memory 155 may store the reconstructed block or picture generated
through the filtering module 150, and the stored reconstructed block or picture may
be provided to the prediction module 120 and 125 when inter prediction is
performed.
Fig. 2 is a block diagram illustrating a video decoder according to another
embodiment of the present invention.
Referring to Fig. 2, the video decoder may include an entropy decoding
module 210, a re-arrangement module 215, a dequantization module 220, an
inverse transform module 225, prediction module 230 and 235, a filtering module
240, and a memory 245.
In case a video bitstream is input from the video encoder, the input
bitstream may be decoded in a procedure opposite to that of the video encoder.
The entropy decoding module 210 may perform an entropy decoding in a
procedure opposite to that of the entropy encoding performed in the entropy
encoding module of the video encoder. Of the pieces of information decoded in
the entropy decoding module 210, information used to derive a prediction block,
such as LCU size information or block size information, is provided to the
prediction module 230 and 235, and the residual values derived through entropy
decoding in the entropy decoding module may be input to the re-arrangement
module 215.
The entropy decoding module 210 may decode information relating to an
intra prediction and an inter prediction performed in the encoder. As described
above, in case there is a predetermined limitation when the video encoder performs
the intra prediction and the inter prediction, the entropy decoding is performed
based on such limitation to thereby receiving information relating to the intra
prediction and inter prediction for the current block.
The re-arrangement module 215 may perform a re-arrangement based on a
method by the encoder for re-arranging a bitstream which is entropy decoded in the
entropy decoding module 210. Such re-arrangement may be performed by
restoring coefficients represented in the form of one-dimensional vectors to 2D
block shape of coefficients.
The dequantization module 220 may perform a dequantization based on the
block of re-arranged coefficients and quantization parameters provided from the
13
encoder.
The inverse transform module 225 may perform an inverse DCT and an
inverse DST, with respect to the DCT and DST which are performed by the
transform module, on a result of the quantization performed in the video encoder.
The inverse transform may be performed in basis of a transmission unit determined
at the video encoder. The transforming module of the video encoder may
selectively perform DCT and DST depending on a plurality of information, such as
a prediction method, a size of a current block and a prediction direction, and the
inverse transform module 225 of the video decoder may perform an inverse
transform based on the transformed information performed by the transform
module of the video encoder.
The prediction module 230 and 235 may generate a prediction block based
on the previously decoded block or the previously decoded picture information as
provided from the memory 245 and the prediction block generation-related
information provided from the entropy decoding module 210.
The prediction module 230 and 235 may include a prediction unit
determining module, an inter prediction module and an intra prediction module.
The prediction unit determining module may receive various information including
prediction mode information of an intra prediction method, motion predictionrelated
information of an inter prediction method, and prediction unit information,
and the various information is input from the entropy decoding module. The
prediction unit determining module may separate a prediction unit from a current
coding unit, and may determine whether an intra prediction is being performed or
an inter prediction is being performed on the prediction unit. The inter prediction
module may perform an inter prediction on the current prediction unit according to
information included in at least one of pictures among pictures prior to a current
picture or pictures after the current picture. The inter prediction module may
perform the inter prediction on the current prediction unit by using information
necessary for inter prediction of the current prediction unit provided from the video
decoder.
It may be determined which one of a skip mode, a merge mode, and an
AMVP mode is a method of motion prediction for a prediction unit included in a
corresponding coding unit, based on the coding unit, in order to perform inter
prediction.
According to an embodiment of the present invention, the inter prediction
module may determine whether a prediction target block adjoins with a boundary
of an LCU (Largest Coding Unit), and may determine whether a first collocated
block is available according to the determination of whether the prediction target
block adjoins with the boundary of the LCU. For example, if it is determined that
the first collocated block is not available, a second collocated block may be
14
determined as a collocated block to derive a temporal motion prediction vector, or
if the first collocated block is not available, the position of the first collocated
block may be changed such that the position-changed first collocated block may be
determined as a collocated block to derive a temporal motion prediction vector.
Further, the inter prediction module may include a predicting module that
determines a reference picture index of a collocated block of the prediction target
block and determines a motion prediction vector of the collocated block. The
collocated block may be adaptively determined according to a location of the
prediction target block in the LCU (Largest Coding Unit). Hereinafter, an
operation of a prediction module according to the present invention is described in
detail.
The intra prediction module may generate a prediction block based on
information of pixels in a current picture. In case the prediction unit is the one
which the intra prediction is applied to, the intra prediction may be performed
based on intra prediction mode information of the prediction unit provided from
the video encoder. The intra prediction module may include an MDIS filter, a
reference pixel interpolating module, and a DC filter. The MDIS filter performs a
filtering on the reference pixels of the current block. For the MDIS filter, it may
be determined whether to apply the filter according to the prediction mode of the
current prediction unit. The filtering on the reference pixels of the current block
may be performed using MDIS filter information and prediction mode of the
prediction unit provided from the video encoder. In case the prediction mode of
the current block is a mode in which filtering is not performed, the MDIS filter
may not apply.
In case that the prediction mode of the prediction unit is a prediction mode
in which the intra prediction is performed based on the pixel values obtained by
interpolating the reference pixel, the reference pixel with a unit less than an integer
pixel may be derived by interpolating the reference pixels. In case that the
prediction mode of the current prediction unit is a prediction mode in which the
prediction block is generated without interpolating the reference pixels, the
reference pixel may not be subjected to interpolation. The DC filter may generate
a prediction block through the filtering, if the prediction mode of the current block
is a DC mode.
The reconstructed block or picture may be provided to the filtering module
240. The filtering module 240 may include a deblocking filter, an offset
correcting module, and an ALF.
Information on whether the corresponding block or picture has been applied
with the deblocking filter may be provided from a video (or image) encoder. If
the deblocking filter has been applied, information on whether the applied
deblocking filter is a strong filter or a weak filter may be provided from the video
15
encoder. The deblocking filter of the video decoder may receive deblocking
filter-related information from the video encoder, and the deblocking filtering may
be performed on the corresponding block in the video decoder. Like the video
encoder, the video decoder may first perform a vertical deblocking filtering and a
horizontal deblocking filtering. An overlapping portion(s) may be subjected to at
least one of the vertical deblocking and horizontal deblocking. In the region where
the vertical deblocking filtering and the horizontal deblocking filtering overlap
each other, either of the vertical deblocking filtering or the horizontal deblocking
filtering, which did not perform previously may be performed for this region.
Such deblocking filtering process enables a parallel processing of the deblocking
filtering.
An offset correcting module may perform an offset correction on the
reconstructed picture based on a type of the offset correction applied to the picture
in an encoding process and information on offset value applied in the encoding
process.
An ALF may perform a filtering according to a comparison between the
reconstructed picture after the filtering and the original picture. The ALF may be
performed on a coding unit based on the information on whether the ALF is
applied and ALF coefficient information, which are provided from the encoder.
Such ALF information may be provided by included in a specific parameter set.
The memory 245 may store a reconstructed picture or a reconstructed block
in order to use this as a reference picture or a reference block, and may provide the
reconstructed picture to an display module.
As described above, even if a term of ‘coding unit’ is used in the
embodiment of the present invention for convenience of description, the coding
unit may be also used as a unit for decoding. Hereinafter, a the prediction method
described below in connection with Figs. 3 to 11 according to an embodiment of
the present invention may be performed in a component, such as a predicting
module as shown in Figs. 1 and 2.
Fig. 3 is a conceptual view illustrating a method of deriving a temporal
prediction motion vector according to an embodiment of the present invention.
Referring to Fig. 3, the temporal prediction motion vector may be derived
based on a motion vector value of a collocated block (colPu) in a collocated picture
(colPic).
The collocated picture is a picture including a collocated block for deriving
temporal prediction motion related information upon performing the inter
prediction method, such as a merge or AMVP. The collocated block may be
defined as a block included in a collocated picture, and the collocated block is
derived based on location information of a prediction target block and has a
temporally different phase from the prediction target block.
16
There may be a plurality of collocated blocks for one prediction target block.
The motion related information of the collocated block included in the collocated
picture may be stored as one representative value with respect to a predetermined
unit. For example, with respect to a unit of 16x16 block size, motion prediction
related information (motion vector, reference picture, etc.) may be determined and
stored as one representative value in a 16x16 block unit.
Fig. 4 is a flowchart illustrating a method of deriving a temporal prediction
motion vector according to an embodiment of the present invention.
Hereinafter, the method of deriving a temporal prediction motion vector,
which is to be described below, may be used in an inter prediction method such as
merge mode or AMVP mode. The method of deriving the temporal prediction
motion vector may be a method of deriving a temporal candidate block (collocated
block) for performing merge mode, a method of deriving a temporal candidate
block (collocated block) for performing AMVP mode, and a method of deriving a
temporal prediction motion vector.
Hereinafter, in an embodiment of the present invention, the collocated block
may be defined and used as a term indicating a temporal candidate block used in
the merge mode and AMVP mode.
Referring to Fig. 4, collocated picture information is derived (step S400).
Location information of a prediction target block, size information of the
prediction target block, and reference picture index information of the prediction
target block may be used to derive collocated picture information, collocated block
information and temporal prediction motion vector.
According to an embodiment of the present invention, the collocated picture
information may be derived based on slice type information (slice_type), reference
picture list information (collocated_from_l0_flag), and reference picture index
information (collocated_ref_idx). Using the the reference picture list information
(collocated_from_l0_flag), if the reference picture list information
(collocated_from_l0_flag) indicates 1, it represents that the collocated picture is
included in a first reference picture list (List 0), and if the reference picture list
information (collocated_from_l0_flag) indicates 0, it represents that the collocated
picture is included in a second reference picture list (List 1).
For example, in case the slice type is slice B and a value of the reference
picture list information (collocated_from_l0_flag) is 0, the collocated picture may
be determined as a picture included in the first reference picture list, and in case
the slice type is slice B and a value of the reference picture list information
(collocated_from_l0_flag) is 1 or in case the slice type is slice P, the collocated
picture may be determined as a picture included in the second reference picture list.
In the case of an inter prediction method using a merge mode, if a
predetermined condition is met, reference picture index information of a
17
neighboring block at a specific position may be determined as information for
collocated picture, and if the predetermined condition is not met, a previous picture
of a current picture may be determined as collocated picture information.
Information for collocated block is derived (step S410).
The information for collocated block may be differently derived depending
on whether part (or portion) of a prediction target block adjoins with a boundary of
an LCU (Largest Coding Unit). Hereinafter, a method of determining a
collocated block depending on the location of a prediction target block and the
boundary of an LCU is described with reference to Figs. 5 to 9.
Fig. 5 is a conceptual view illustrating a location of a collocated block to
derive a temporal motion vector according to an embodiment of the present
invention.
Referring to Fig. 5, blocks at various positions with respect to a prediction
target block may be used as collocated blocks to derive a temporal motion vector.
The collocated blocks that may be used to derive the temporal motion vector may
be classified depending on the locations as follows.
In case a point located at a top-left of a prediction target block is at (xP, yP),
the width of the prediction target block is nPSW, and the height of the prediction
target block is nPSH, a first collocated block 500 may be a block including a point
(xP+nPSW, yP+nPSH) in the collocated picture, a second collocated block 510
may be a block including a point (xP+nPSW-MinPuSize, yP+nPSH) in the
collocated picture, a third collocated block 520 may be a block including a point
(xP+nPSW, yP+nPSH-MinPuSize) in the collocated picture, a fourth collocated
block 530 may be a block including a point (xP+nPSW-1, yP+nPSH-1) in the
collocated picture, a fifth collocated block 540 may be a block including a point
(xP+(nPSW>>1), yP+(nPSH>>1)) in the collocated picture, and a sixth collocated
block 550 may be a block including a point (xP+(nPSW>>1)-1, yP+(nPSH>>1)-1)
in the collocated picture.
The collocated block may be adaptively determined according to a position
of a current prediction unit located within in the LCU. A positional relationship
between a prediction target block and a boundary of the LCU may be categorized
in the following cases: 1) where a lower end and a right side of the prediction
target block do not adjoin with the LCU boundary, 2) where only the lower end of
the prediction target block adjoins with the LCU boundary, 3) where both the right
side and the lower end of the prediction target block adjoin with the LCU boundary,
and 4) where only the right side of the prediction target block adjoins with the
LCU boundary.
According to an embodiment of the present invention, the collocated block
may be adaptively determined in a different way depending on the location of the
prediction target block in the LCU.
18
1) In case that the lower end and right side of the prediction target block do
not adjoin with the LCU boundary, the first collocated block and the fifth
collocated block may be sequentially used as a collocated block with an
availability check in order to derive a temporal motion vector.
2) In case that only the lower end of the prediction target block adjoins with
the LCU boundary, the third collocated block and the fifth collocated block may be
sequentially used as a collocated block with the availability check in order to
derive a temporal motion vector.
3) In case that both the right side and lower end of the prediction target
block adjoin with the LCU boundary, the fourth collocated block and the fifth
collocated block may be sequentially used as a collocated block with the
availability check in order to derive a temporal motion vector.
4) In case that only the right side of the prediction target block adjoins with
the LCU boundary, the second collocated block and the fifth collocated block may
be sequentially used as a collocated block with the availability check in order to
derive a temporal motion vector.
That is, according to an embodiment of the present invention, depending on
the location of the current block in the LCU, a temporal candidate block may be
adaptively determined. The positions of pixels to specify a temporal candidate
block for a case when the lower boundary of the current block adjoins with the
LCU boundary may be different from the positions of pixels to specify a temporal
candidate block for a case when the lower boundary of the current block does not
adjoin with the LCU boundary. And, the positions of pixels to specify a temporal
candidate block for a case when the lower boundary of the current block adjoins
with the LCU boundary may be different from the positions of pixels to specify a
temporal candidate block for a case when only the right boundary of the current
block adjoins with the LCU boundary.
According to another embodiment of the present invention, a method may
be used, in which a collocated block may be determined (or selected) adaptively
and differently depending on the position of the prediction target block in the LCU
such that the collocated block and the prediction target block are located within
same LCU, or the collocated block may not be used if the collocated block and the
target prediction block are not located within same LCU.
Fig. 6 is a conceptual view illustrating a method of determining a collocated
block to derive a motion prediction vector according to an embodiment of the
present invention.
Referring to Fig. 6, the positions of collocated blocks of a plurality of
prediction units included in one LCU may be known.
For the cases of PU0, PU1, PU2, and PU5, the prediction units are
prediction units inside of the LCU, and the first collocated block may be firstly
19
used as a collocated lock to derive a temporal motion vector.
For the cases of PU4 and PU7, the boundaries of the prediction units adjoin
with only the lower boundary of the LCU, and the third collocated block may be
firstly used as collocated block to derive a temporal motion vector.
For the case of PU8, the boundary of the prediction unit adjoins with both
the lower boundary and the right boundary of the LCU, and the fourth collocated
block may be firstly used as a collocated block to derive a temporal motion vector.
For the cases of PU3 and PU6, the boundaries of the prediction units adjoin
with only the right boundary of the LCU, and the second collocated block may be
firstly used as a collocated block to derive a temporal motion vector.
That is, as described above, a temporal candidate block is adaptively
determined depending on the location of the current block in the LCU, and the
positions of pixels to specify a temporal candidate block for cases when the lower
boundary of the current block adjoins with the LCU boundary (cases of PU4, PU7
and PU8) and for cases when the lower boundary of the current block does not
adjoin with the LCU boundary (cases of PU0, PU1, PU2, PU3, PU5, and PU6) are
different from each other. Further, the positions of pixels to specify a temporal
candidate block may be different for cases when the lower boundary of the current
block adjoins with the LCU boundary (cases of PU4, PU7, and PU8) and for cases
when only the right boundary of the current block adjoins with the LCU boundary
(cases of PU3 and PU6).
According to another embodiment of the present invention, as long as a
collocated block is located within same LCU together with the prediction target
block, the collocated block is adaptively and differently determined depending on
the location of the prediction target block in the LCU. If a specific collocated
block is not located within same LCU together with the prediction target block,
such specific collocated block may be not available. For example, if the lower
boundary of a prediction block adjoins with the lower boundary of the LCU like
PU4, PU7, and PU8, the first collocated block may be marked (or indicated) as
unavailable, and the fifth collocated block may be used instead as a collocated
block to derive a temporal prediction vector.
As such, as a method of deriving a collocated block, a method may be used
that, categorizing characteristics of a prediction target block as described above
depending on the location of the prediction target block and LCU boundary, selects
a block to be used as a collocated block depending on the categorized location of
the prediction target block. Preferably, it is assumed that the first collocated
block and the fifth collocated block may be sequentially used as a collocated block
to derive a temporal motion vector. After checking an availability of the first
collocated block (for example, whether the lower boundary of the prediction target
block adjoins with the LCU), a collocated block other than the first collocated
20
block may be determined as a collocated block to derive a temporal motion vector.
For example, if the first collocated block is determined as unavailable through
steps of determining whether the prediction target block adjoins with the boundary
of the LCU (Largest Coding Unit), the collocated block to derive a temporal
motion vector may be changed to other collocated block (e.g., third collocated
block), or the fifth collocated block may be used directly without using the first
collocated block.
Specifically, the above method may be performed through the following
steps:
1) Step of determining whether the boundary of the prediction target block
adjoins with the boundary of the LCU (Largest Coding Unit),
2) Step of determining whether the first collocated block is available
depending on whether the boundary of the prediction target block adjoins with the
LCU boundary. Specifically in step 2), when the lower boundary of the
prediction target block adjoins with the LCU boundary, it may be determined that
the first collocated block is not available,
3) Step of determining a collocated block other than the first collocated
block as a collocated block to derive a temporal prediction motion vector when the
first collocated block is not available. Specifically, in step 3), for a case that the
lower boundary of the prediction target block adjoins with the LCU boundary and
for a case that the right boundary of the prediction target block adjoins with the
LCU boundary, different collocated blocks for each different case may be
determined as collocated blocks to derive a temporal prediction motion vector ,
4) Step of determining the first collocated block as a collocated block to
derive a temporal prediction motion vector if the first collocated block is available,
and determining an availability of the fifth collocated block if the first collocated
block is not available.
The above steps may be optional steps, and the sequential relationship of
the steps or the method of the determination may be changed without departing
from the gist of the present invention.
Fig. 7 is a conceptual view illustrating a case where a prediction target
block adjoins with a lower boundary of an LCU according to an embodiment of the
present invention.
Referring to Fig. 7, a case is shown that the location of the collocated block
is changed when the prediction target block (PU, PU7, or PU8) is located at the
lower boundary of the LCU. In case the prediction target block (PU4, PU7, or
PU8) is located at the lower boundary of the LCU, the location of the collocated
block may be set so that the motion prediction-related information may be derived
even without searching an LCU positioned under a current LCU among LCUs.
For example, a temporal prediction motion vector may be derived by using the
21
third collocated block rather than the first collocated block of the prediction target
block. 1) in case that only the right boundary of the LCU is adjoined, depending
on availability, the first collocated block and the fifth collocated block are
sequentially determined as a collocated block to derive a temporal prediction
motion vector, 2) in case that the lower boundary of the LCU is adjoined,
depending on availability, the third collocated block and the fifth collocated block
may be sequentially determined as a collocated block to derive a temporal
prediction motion vector. That is, according to an embodiment of the present
invention, the positions of pixels to specify a temporal candidate block may be
different for a case when the lower boundary of the current block adjoins with the
LCU boundary and for a case when the lower boundary of the current block does
not adjoin with the LCU boundary.
Referring back to Fig. 4, based on the collocated block determined through
the method described above in connection with Figs. 5 to 7, a collocated block
motion prediction vector (mvLXCol) and collocated block availability information
(availableFlagLXCol) are derived(step S420).
The collocated block availability information (availableFlagLXCol) and
motion vector (mvLXCol) of the collocated block, which is to be used for inter
prediction of the prediction target block based on the collocated block information
determined through the processes shown in Figs. 5 to 7, may be derived by the
following method:
1) If the collocated block (colPu) is encoded based on an intra prediction
mode, if the collocated block (colPu) is not available, if the collocated picture
(colPic) is not available for predicting a temporal prediction motion vector, or if
inter prediction is performed without using a temporal prediction motion vector,
the collocated block motion vector (mvLXCol) and the collocated block
availability information (availableFlagLXCol) may be set as 0.
2) Other than the case 1), the collocated block motion vector information
(mvLXCol) and the collocated block availability information
(availableFlagLXCol) may be derived through a flag (PredFlagL0) and a flag
(PredFlagL1), where the flag (PredFlagL0) indicates whether L0 list is used or not,
and the flag (PredFlagL1) indicates whether L1 list is used or not.
First, if it is determined that the inter prediction has been performed on the
collocated block without using list L0 (the flag (PredFlagL0) is equal to 0), motion
prediction-related information of the collocated block, such as mvCol information,
refldxCol information, and listCol information, may be set as L1 and
MvL1[xPCol][yPCol], RefIdxL1[xPCol][yPCol], which are motion predictionrelated
information of the collocated block derived by using list L1, and the
collocated block availability information (availableFlagLXCol) may be set as 1.
In other cases, if it is determined that inter prediction has been performed
22
on collocated block using list L0 (the flag (PredFlagL0) is equal to 1), motion
prediction-related information of the collocated block, such as mvCol information,
refldxCol information, and listCol information, may be set separately for a case
where PredFlagL1 is 0 and for a case where PredFlagL1 is 1, and the collocated
block availability information (availableFlagLXCol) may be set as 1.
The derived mvLXCol is scaled (step S430).
To use the mvLXCol derived through step S420 as a temporal prediction
motion vector of the prediction target block, a derived mvLXCol value may be
scaled based on distance information relating to a distance between the collocated
picture including the collocated block and the collocated block reference picture
referred by the collocated block and a distance between the picture including the
prediction target block and a reference picture referred by the prediction target
block. After the derived mvLXCol value is scaled, the temporal prediction
motion vector can be derived.
Hereinafter, according to an embodiment of the present invention, a method
of performing an inter prediction, such as merge and AMVP, is described.
Fig. 8 is a flowchart illustrating an inter prediction method using a merge
mode according to an embodiment of the present invention.
Referring to Fig. 8, motion prediction-related information may be derived
from a spatial merging candidate (step S1000).
The spatial merging candidate may be derived from neighboring prediction
units of a prediction target block. To derive the spatial merging candidate,
information on the width and height of the prediction unit, MER (Motion
Estimation Region) information, singleMCLFlag information, and partition
position information may be received. Based on such input information,
availability information (availableFlagN) according to the position of the spatial
merging candidate, reference picture information (refldxL0, refldxL1), list
utilization information (predFlagL0N, redFlagL1N), and motion vector
information (mvL0N, mvL1N) may be derived. A plurality of blocks neighboring
to the prediction target block may be spatial merging candidates.
Fig. 9 is a conceptual view illustrating positions of spatial merging
candidates according to an embodiment of the present invention.
Referring to Fig. 9, in case that a location of a point at a top-left of the
prediction target block is (xP, yP), a width of the prediction target block is nPSW,
and a width of the prediction target block is nPSH, the spatial merging candidates
may be a block A0 including the point (xP-1, yP+nPSH), a block A1 including the
point (xP-1, yP+nPSH-MinPuSize), a block B0 including the point (xP+nPSW, yP-
1), a block B1 including the point (xP+nPSW-MinPuSize, yP-1), and a block B2
including the point (xP-MinPuSize, yP-1).
Referring back to Fig. 8, a reference picture index value of the temporal
23
merging candidate is derived (step S1010).
The reference picture index value of the temporal merging candidate, as an
index value of a collocated picture including the temporal merging candidate
(collocated block), may be derived through specific conditions as follows. The
following conditions are arbitrary and may vary. For example, in case that a
location of point at a top-left of the prediction target block is (xP, yP), the width of
the prediction target block is nPSW, and the width of the prediction target block is
nPSH, when 1) there exists a neighboring prediction unit of the prediction target
block corresponding to position (xP-1, yP+nPSH-1) (hereinafter, referred to as a
reference picture index derivation neighboring prediction unit), 2) the partition
index value of the reference picture index derivation neighboring prediction unit is
0, 3) the reference picture index derivation neighboring prediction unit is not a
block on which prediction performed using an intra prediction mode, and 4) the
prediction target block and the reference picture index derivation neighboring
prediction block do not belong to the same MER (Motion Estimation Region), the
reference picture index value of the temporal merging candidate may be
determined as the same value as the reference picture index value of the reference
picture index derivation neighboring prediction unit. In the case of failing to
satisfy these conditions, the reference picture index value of the temporal merging
candidate may be set as 0.
The temporal merging candidate block (collocated block) is determined,
and motion prediction-related information is derived from the collocated block
(step S1020).
According to an embodiment of the present invention, the temporal merging
candidate block (collocated block) may be adaptively determined depending on the
location of the prediction target block in the LCU so that the collocated block is
included in the same LCU together with the prediction target block.
1) In case that the lower end and the right side of the prediction target block
do not adjoin with the LCU boundary, determining an availability, the first
collocated block and the fifth collocated block may be sequentially used as a
collocated block to derive a temporal motion vector.
2) In case that only the lower end of the prediction target block adjoins with
the LCU boundary, determining an availability, the third collocated block and the
fifth collocated block may be sequentially used as a collocated block to derive a
temporal motion vector.
3) In case that both the right side and the lower end of the prediction target
block adjoin with the LCU boundary, determining an availability, and the fourth
collocated block and the fifth collocated block may be sequentially used as
collocated blocks to induce a temporal motion vector.
4) In case only the right side of the prediction target block is adjacent to the
24
LCU boundary, availability is determined, and the second collocated block and the
fifth collocated block may be sequentially used as collocated blocks to induce a
temporal motion vector.
According to an embodiment of the present invention, a method may be
used that enables a collocated block to be adaptively and differently determined
depending on the position of the prediction target block in the LCU to be present at
a position included in one LCU together with the prediction target block, or the
collocated block not included in one LCU together with the prediction target block
may not be used.
As described above, as a method of producing a collocated block, a method
may be used of separating characteristics of a prediction target block as described
above depending on the position of the prediction target block and LCU boundary
and determining a block to be immediately used as a collocated block depending
on the position of the separated prediction target block. However, the first
collocated block and the fifth collocated block may be first assumed to be
sequentially used as collocated blocks to induce a temporal motion vector, whether
the first collocated block is available (for example, whether the lower boundary of
the prediction target block is adjacent to the LCU) is determined, and then, a
collocated block other than the first collocated block may be determined as a
collocated block to induce a temporal motion vector.
A merge candidate list is configured (step S1030).
The merging candidate list may be constructed to include at least one of
spatial merging candidates and a temporal merging candidate. The spatial
merging candidates and temporal merging candidate included in the merging
candidate list may be arranged with a predetermined priority.
The merging candidate list may be constructed to have a fixed number of
merging candidates, and if the number of merging candidates is less than the fixed
number, the motion prediction-related information owned by the merging
candidates is combined to generate merging candidates or zero vectors are
generated as merging candidates, thereby generating the merging candidate list.
Fig. 10 is a flowchart illustrating an inter prediction method using AMVP
according to an embodiment of the present invention.
Referring to Fig. 10, motion prediction-related information is derived from
spatial AMVP candidate blocks (step S1200).
To derive the reference picture index information and a prediction motion
vector of the prediction target block, the spatial AMVP candidate block(s) may be
derived from neighboring prediction blocks of the prediction target block.
Referring back to Fig. 9, one of block A0 and block A1 may be used as a
first spatial AMVP candidate block, and one of block B0, block B1, and block B2
may be used as a second spatial AMVP candidate block, thereby deriving the
25
spatial AMVP candidate blocks.
Motion prediction-related information is derived from a temporal AMVP
candidate block (step S1210).
According to an embodiment of the present invention, the collocated block
may be adaptively determined depending on the location of the prediction target
block in the LCU so that the collocated block is included in same LCU together
with the prediction target block.
1) In case that the lower end and the right side of the prediction target block
do not adjoin with the LCU boundary, the first collocated block and the fifth
collocated block may be sequentially used as a collocated block to derive a
temporal motion vector with an availability check.
2) In case that only the lower end of the prediction target block adjoins with
the LCU boundary, the third collocated block and the fifth collocated block may be
sequentially used as a collocated block to derive a temporal motion vector with an
availability check.
3) In case that both the right side and the lower end of the prediction target
block adjoin with the LCU boundary, the fourth collocated block and the fifth
collocated block may be sequentially used as a collocated block to derive a
temporal motion vector with an availability check.
4) In case that only the right side of the prediction target block adjoins with
the LCU boundary, the second collocated block and the fifth collocated block may
be sequentially used as a collocated block to derive a temporal motion vector with
an availability check.
According to an embodiment of the present invention, a method that the
collocated block not included in same LCU together with the prediction target
block may not be used, as well as a method that a collocated block is adaptively
determined depending on the location of the prediction target block in the LCU to
be present at a location included in same LCU together with the prediction target
block, may be used.
In the step S1200 of deriving the spatial AMVP candidate blocks, when the
first spatial AMVP candidate block and the second spatial AMVP candidate block
are determined as available, and the derived motion prediction vector values are
not the same, the step S1210 of deriving a temporal prediction motion vector may
not be performed.
An AMVP candidate list is constructed (step S1220).
The AMVP candidate list is constructed by using the motion predictionrelated
information derived through at least one of steps S1200 and S1210. In
case the same motion prediction-related information exists in the constructed
AMVP candidate list, one value among the same motion prediction-related
information may be used as an AMVP candidate value. The motion prediction26
related information included in the AMVP candidate list may include a fixed
number of candidate values only.
Although the embodiments of the present invention have been described
thus far, it may be understood by those skilled in the art to which the present
invention pertains that various modifications and variations may be made to the
present invention without departing from the spirit and scope of the present
invention.
27
I/We claim
【Claim 1】
A method of deriving a candidate motion prediction vector, the method
comprising:
determining a reference picture index of a collocated block of a prediction
target block; and
determining a motion prediction vector of the collocated block,
wherein the collocated block is a block adaptively determined by a location
of the prediction target block within a Largest Coding Unit (LCU).
【Claim 2】
The method of claim 1, wherein the collocated block is differently
determined by deciding whether a lower boundary of the prediction target block
adjoins with an LCU boundary.
【Claim 3】
The method of claim 1, wherein the collocated block is differently
determined by deciding whether a lower boundary of the prediction target block
adjoins with an LCU boundary and whether only a right boundary of the prediction
target block adjoins with the LCU boundary.
【Claim 4】
The method of claim 1, wherein the collocated block is determined by
referencing positions of pixels within the LCU.
【Claim 5】
The method of claim 1, wherein if a left side or lower boundary of the
prediction target block does not adjoined with the LCU boundary, a first collocated
block and a fifth collocated block are sequentially determined as the collocated
block according to an availability of the collocated block at a corresponding
position, and
wherein if a location of a point at a top-left of the prediction target block is
(xP, yP), a width of the prediction target block is nPSW, and a height of the
prediction target block is nPSH, the first collocated block is a block including a
point at (xP+nPSW, yP+nPSH) within a collocated picture, and the fifth collocated
block is a block including a point at (xP+(nPSW>>1), yP+(nPSH>>1)) within the
collocated picture.
28
【Claim 6】
A method of deriving a candidate motion prediction vector, the method
comprising:
determining whether a boundary of a prediction target block adjoins with
a boundary of a Largest Coding Unit (LCU); and
determining an availability of a first collocated block according to the
determination of whether the boundary of the prediction target block adjoins with
the boundary of the LCU.
【Claim 7】
The method of claim 6, further comprising: if it is determined that the first
collocated block is not available, determining other collocated block except for
the first collocated block as a collocated block to derive a temporal prediction
motion vector.
【Claim 8】
The method of claim 7, wherein the step of determining the other
collocated block except for the first collocated block as the collocated block to
derive the temporal prediction motion vector if the first collocated block is not
available, is a step for determining different collocated blocks to derive the
temporal prediction motion vector for a case where a lower boundary of the
prediction target block adjoins with the boundary of the LCU and for a case where
only a right boundary of the prediction target block adjoins with the boundary of
the LCU.
【Claim 9】
The method of claim 6, wherein the step of determining the availability of
the first collocated block according to the determination of whether the boundary
of the prediction target block is adjoined with the boundary of the LCU, is a step
for determining the first collocated block as unavailable if a lower boundary of the
prediction target block adjoins with the boundary of the LCU.
【Claim 10】
The method of claim 6, further comprising the step of determining the first
collocated block as the collocated block to derive the temporal prediction motion
vector if the first collocated block is available, or determining an availability of a
fifth collocated block if the first collocated block is not available ,
wherein if a location of a point at a top-left of the prediction target block is
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(xP, yP), a width of the prediction target block is nPSW, and a height of the
prediction target block is nPSH, the first collocated block is a block including a
point (xP+nPSW, yP+nPSH) within a collocated picture, and the fifth collocated
block is a block including a point (xP+(nPSW>>1), yP+(nPSH>>1)) within the
collocated picture.
【Claim 11】
A video decoding apparatus, the apparatus comprising:
an entropy decoding unit that decodes LCU size information; and
a prediction unit that determines a reference picture index of a collocated
block of a prediction target block and determines a motion prediction vector of the
collocated block, wherein the collocated block is a block adaptively determined by
a location of the prediction target block within a Largest Coding Unit (LCU).
【Claim 12】
The apparatus of claim 11, wherein the collocated block is differently
determined by deciding whether a lower boundary of the prediction target block
adjoins with an LCU boundary.
【Claim 13】
The apparatus of claim 11, wherein the collocated block is differently
determined by deciding whether a lower boundary of the prediction target block
adjoins with an LCU boundary and whether only a right boundary of the prediction
target block adjoins with the LCU boundary.
【Claim 14】
The apparatus of claim 11, wherein the collocated block is determined by
referencing positions of pixels within the LCU.
【Claim 15】
The apparatus of claim 11, wherein if a left side or lower boundary of the
prediction target block is not adjoined with the LCU boundary, a first collocated
block and a fifth collocated block are sequentially determined as the collocated
block according to an availability of the collocated block at a corresponding
position, and
wherein ifa location of a point at a top-left of the prediction target block is
(xP, yP), a width of the prediction target block is nPSW, and a height of the
prediction target block is nPSH, the first collocated block is a block including a
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point (xP+nPSW, yP+nPSH) within a collocated picture, and the fifth collocated
block is a block including a point (xP+(nPSW>>1), yP+(nPSH>>1)) within the
collocated picture.
【Claim 16】
A video decoding apparatus, the apparatus comprising:
an entropy decoding unit that decodes LCU size information; and
a prediction unit that determines whether a boundary of a prediction target
block adjoins with a boundary of a Largest Coding Unit (LCU) and determines an
availability of a first collocated block according to the determination of whether
the boundary of the prediction target block adjoins with the boundary of the LCU.
【Claim 17】
The apparatus of claim 16, wherein the prediction unit determines other
collocated block except for the first collocated block as a collocated block to derive
a temporal prediction motion vector if it is determined that the first collocated
block is not available.
【Claim 18】
The apparatus of claim 17, wherein the prediction unit determines different
collocated blocks to derive the temporal prediction motion vector for a case where
a lower boundary of the prediction target block adjoins with the boundary of the
LCU and for a case where only a right boundary of the prediction target block
adjoins with the boundary of the LCU.
【Claim 19】
The apparatus of claim 16, wherein the prediction unit determines the first
collocated block as unavailable if a lower boundary of the prediction target block
adjoins with the boundary of the LCU.
【Claim 20】
The apparatus of claim 16, wherein the prediction unit determines the first
collocated block as the collocated block to derive the temporal prediction motion
vector if the first collocated block is available, or determines an availability of a
fifth collocated block if the first collocated block is not available, and
wherein if a location of a point at a top-left of the prediction target block is
(xP, yP), a width of the prediction target block is nPSW, and a height of the
prediction target block is nPSH, the first collocated block is a block including a
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point (xP+nPSW, yP+nPSH) within a collocated picture, and the fifth collocated
block is a block including a point (xP+(nPSW>>1), yP+(nPSH>>1)) within the
collocated picture.