U.S. patent application number 14/177292 was filed with the patent office on 2014-06-12 for video encoding method and apparatus and video decoding method and apparatus, based on hierarchical coded block pattern information.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. The applicant listed for this patent is SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Min-su CHEON, Hae-kyung JUNG, Il-koo KIM, Jung-hye MIN.
Application Number | 20140161194 14/177292 |
Document ID | / |
Family ID | 43586684 |
Filed Date | 2014-06-12 |
United States Patent
Application |
20140161194 |
Kind Code |
A1 |
CHEON; Min-su ; et
al. |
June 12, 2014 |
VIDEO ENCODING METHOD AND APPARATUS AND VIDEO DECODING METHOD AND
APPARATUS, BASED ON HIERARCHICAL CODED BLOCK PATTERN
INFORMATION
Abstract
A method and apparatus for decoding video and a method and
apparatus for encoding video are provided. The method for decoding
video includes: receiving and parsing a bitstream of encoded video;
extracting, from the bitstream, encoded image data of a current
picture assigned to a maximum coding unit of the current picture,
information regarding a coded depth of the maximum coding unit,
information regarding an encoding mode, and coding unit pattern
information indicating whether texture information of the maximum
coding units has been encoded; and decoding the encoded image data
for the maximum coding unit, based on the information regarding the
coded depth of the maximum coding unit, the information regarding
the encoding mode, and the coding unit pattern information.
Inventors: |
CHEON; Min-su; (Suwon-si,
KR) ; JUNG; Hae-kyung; (Seoul, KR) ; MIN;
Jung-hye; (Suwon-si, KR) ; KIM; Il-koo;
(Osan-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAMSUNG ELECTRONICS CO., LTD. |
Suwon-si |
|
KR |
|
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
Suwon-si
KR
|
Family ID: |
43586684 |
Appl. No.: |
14/177292 |
Filed: |
February 11, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12856272 |
Aug 13, 2010 |
|
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14177292 |
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Current U.S.
Class: |
375/240.18 |
Current CPC
Class: |
H04N 19/70 20141101;
H04N 19/60 20141101; H04N 19/96 20141101; H04N 19/136 20141101;
H04N 19/44 20141101; H04N 19/176 20141101; H04N 19/119 20141101;
H04N 19/184 20141101; H04N 19/122 20141101; H04N 19/61 20141101;
H04N 19/147 20141101 |
Class at
Publication: |
375/240.18 |
International
Class: |
H04N 19/30 20060101
H04N019/30; H04N 19/60 20060101 H04N019/60 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 14, 2009 |
KR |
10-2009-0075337 |
Claims
1. A method of decoding video, the method comprising: receiving and
parsing a bitstream of encoded video; obtaining, from the
bitstream, encoded image data of a chroma component of a
transformation unit included in a maximum coding unit of the
current picture, information regarding a coded depth of the maximum
coding unit, and hierarchical coding unit pattern information for
at least one transformation depth; determining, based on a first
hierarchical coding unit pattern information regarding a chroma
component of the transformation unit of a first transformation
depth, whether second hierarchical coding unit pattern information
regarding chroma components of four transformation units of a
second transformation depth split from the transformation unit of
the first transformation depth has been encoded; and decoding the
encoded image data of the chroma component of the transformation
unit, based on the obtained information regarding the coded depth
of the maximum coding unit and the hierarchical coding unit pattern
information, wherein the maximum coding unit comprises the
transformation unit for performing transformation on the maximum
coding unit, the transformation unit is hierarchically split
according to the at least one transformation depth, and the second
transformation depth is lower than the first transformation
depth.
2. The method of claim 1, wherein the determining comprises, when
the first hierarchical coding unit pattern information indicates
that the second hierarchical coding unit pattern information
regarding the second transformation depth is present, obtaining the
second hierarchical coding unit pattern information regarding the
second transformation depth from the bitstream.
3. The method of claim 1, wherein the determining comprises, when
the first hierarchical coding unit pattern information indicates
that the second hierarchical coding unit pattern information
regarding the second transformation depth is not present, decoding
the chroma component of the transformation unit of the first
transformation depth.
4. The method of claim 3, wherein the decoding the transformation
unit of the first transformation depth comprises decoding the
transformation unit of the first transformation depth based on
coding unit pattern information indicating whether texture
information of the chroma component of the transformation unit has
been encoded.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATION
[0001] This application is a Continuation Application of
application Ser. No. 12/856,272 filed on Aug. 13, 2010, which
claims priority from Korean Patent Application No. 10-2009-0075337,
filed on Aug. 14, 2009 in the Korean Intellectual Property Office,
the disclosure of which is incorporated herein in its entirety by
reference.
BACKGROUND
[0002] 1. Field
[0003] Exemplary embodiments relate to encoding and decoding
video.
[0004] 2. Description of the Related Art
[0005] As hardware for reproducing and storing high resolution or
high quality video content is being developed and supplied, a need
for a video codec for effectively encoding or decoding the high
resolution or high quality video content is increasing. In a
related art video codec, video is encoded according to a limited
encoding method based on a macroblock having a predetermined size.
Also, in the related art video codec, coded block pattern
information is encoded in units of macro blocks.
SUMMARY
[0006] Apparatuses and methods consistent with exemplary
embodiments provide encoding and decoding video by using
information indicating whether texture information of a coding unit
has been encoded and in consideration of a hierarchical depth.
[0007] According to an aspect of an exemplary embodiment, there is
provided a method of decoding video, the method including:
receiving and parsing a bitstream of encoded video; extracting,
from the bitstream, encoded image data of a current picture
assigned to a maximum coding unit of the current picture,
information regarding a coded depth of the maximum coding unit,
information regarding an encoding mode, and coding unit pattern
information indicating whether texture information of the maximum
coding unit has been encoded; and decoding the encoded image data
for the maximum coding unit, based on the information regarding the
coded depth of the maximum coding unit, the information regarding
the encoding mode, and the coding unit pattern information.
[0008] The coding unit may be characterized by a maximum size and a
depth.
[0009] The depth may indicate a number of times a coding unit is
hierarchically split, and as the depth deepens, deeper coding units
according to depths may be split from the maximum coding unit to
obtain minimum coding units.
[0010] The depth may be deepened from an upper depth to a lower
depth.
[0011] As the depth deepens, the number of times the maximum coding
unit is split may increase, and a total number of possible times
the maximum coding unit is split may correspond to a maximum
depth.
[0012] The maximum size and the maximum depth of the coding unit
may be predetermined.
[0013] Coding unit pattern information regarding the maximum coding
unit may include at least one of coding unit pattern information
corresponding to coded depth, which is set for a coding unit
corresponding to the coded depth, and hierarchical coding unit
pattern information according to transformation depths, which
indicates whether hierarchical coding unit pattern information
regarding a lower depth has been encoded.
[0014] If the coding unit pattern information regarding the coding
units according to the coded depths indicates that the texture
information of the maximum coding units has been encoded, the
decoding the encoded image data may include extracting
transformation unit pattern information indicating whether texture
information of at least one transformation unit included in the
coding unit corresponding to the coded depth has been encoded.
[0015] If the transformation unit pattern information indicates
that texture information of the transformation unit has been
encoded, the decoding the encoded image data may include decoding
the encoded texture information.
[0016] If the transformation unit pattern information indicates
that texture information of the transformation unit has not been
encoded, the decoding the encoded image data may include decoding
the transformation unit by using information regarding
transformation units adjacent to the transformation unit.
[0017] The coding unit pattern information corresponding to coded
depth may be extracted according to color components of the image
data.
[0018] If the coding unit corresponding to the coded depth includes
at least four transformation units, the first group may be divided
into four lower groups, and predetermined-bit coding unit pattern
information corresponding to the coded depth may further be
extracted for each of the four lower groups.
[0019] According to an aspect of another exemplary embodiment,
there is provided a method of encoding video, the method including:
splitting a current picture of the video into a maximum coding
unit; determining a coded depth to output a final encoding result
according to at least one split region, which is obtained by
splitting a region of the maximum coding unit according to depths,
by encoding the at least one split region, based on a depth that
deepens in proportion to a number of times the region of the
maximum coding unit is split; and outputting image data that is the
final encoding result according to the at least one split region,
and encoding and outputting information about the coded depth and a
prediction mode and coding unit pattern information one of the
maximum coding unit, wherein the coding unit pattern information
indicates whether texture information of the maximum coding unit
has been encoded.
[0020] The outputting of the image data may include setting and
encoding the coding unit pattern information, based on whether all
transformation coefficients of the texture information of the
maximum coding unit are 0.
[0021] The outputting of the image data may include setting and
encoding the coding unit pattern information corresponding to coded
depth, according to the coded depth of the maximum coding unit,
based on whether all transformation coefficients of the coding unit
corresponding to the coded depths are 0.
[0022] If hierarchical coding unit pattern information and texture
information regarding a coding unit corresponding to an upper depth
of a current depth are not encoded, then the outputting of the
image data may include setting and encoding hierarchical coding
unit pattern information from an uppermost depth to the current
depth.
[0023] The method may further include determining whether at least
one of the coding unit pattern information corresponding to coded
depth and the hierarchical coding unit pattern information for each
of the at least one transformation depth, is to be used with
respect to at least one of the current picture, a slice, and the
maximum coding unit.
[0024] The outputting of the coding unit pattern information may
include determining whether transformation unit pattern information
is to be set for a transformation unit included in a coding unit
corresponding to the coded depth, based on coding unit pattern
information regarding the maximum coding unit, wherein the
transformation unit pattern information indicates whether texture
information of the transformation unit has been encoded.
[0025] According to an aspect of another exemplary embodiment,
there is provided an apparatus for decoding video, the apparatus
including: a receiver which receives and parses a bitstream of
encoded video; an extractor which extracts, from the bitstream,
encoded image data of a current picture assigned to a maximum
coding unit, information regarding a coded depth of the maximum
coding unit, information regarding an encoding mode, and coding
unit pattern information indicating whether texture information of
the maximum coding unit has been encoded; and an image data decoder
which decodes the encoded image data in the maximum coding unit,
based on the information regarding thee coded depth of the maximum
coding unit, the information regarding the encoding mode, and the
coding unit pattern information.
[0026] According to an aspect of another exemplary embodiment,
there is provided an apparatus for encoding video, the apparatus
including: a maximum coding unit splitter which splits a current
picture into a maximum coding unit; a coding unit determiner which
determines a coded depth to output a final encoding result
according to at least one split region, which is obtained by
splitting a region of each of the maximum coding unit according to
depths, by encoding the at least one split region, based on a depth
that deepens in proportion to a number of times the region of the
maximum coding unit is split; and an output unit which outputs
image data that is the final encoding result according to the at
least one split region, and which encodes and outputs information
about the coded depth and an encoding mode and coding unit pattern
information of the maximum coding unit, wherein the coding unit
pattern information indicates whether texture information of each
of the at least one maximum coding unit has been encoded.
[0027] According to an aspect of another exemplary embodiment,
there is provided a computer readable recording medium having
recorded thereon a computer program for executing the above method
of decoding video.
[0028] According to an aspect of another exemplary embodiment,
there is provided a computer readable recording medium having
recorded thereon a computer program for executing the above method
of encoding video.
[0029] According to an aspect of another exemplary embodiment,
there is provided a method of decoding video, the method including:
extracting, from a bitstream of encoded video, encoded image data
of a current picture assigned to a maximum coding unit of the
current picture, information regarding a coded depth of the maximum
coding unit, and coding unit pattern information indicating whether
texture information of the maximum coding unit has been encoded;
and decoding the encoded image data for the maximum coding unit,
based on the extracted information regarding the coded depth of the
maximum coding unit, and the coding unit pattern information.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The above and/or other aspects will become more apparent by
describing in detail exemplary embodiments thereof with reference
to the attached drawings in which:
[0031] FIG. 1 is a block diagram of a video encoding apparatus
according to an exemplary embodiment;
[0032] FIG. 2 is a block diagram of a video decoding apparatus
according to an exemplary embodiment;
[0033] FIG. 3 is a diagram for describing a concept of coding units
according to an exemplary embodiment;
[0034] FIG. 4 is a block diagram of an image encoder based on
coding units according to an exemplary embodiment;
[0035] FIG. 5 is a block diagram of an image decoder based on
coding units according to an exemplary embodiment;
[0036] FIG. 6 is a diagram illustrating deeper coding units
according to depths, and partitions according to an exemplary
embodiment;
[0037] FIG. 7 is a diagram for describing a relationship between a
coding unit and transformation units, according to an exemplary
embodiment;
[0038] FIG. 8 is a diagram for describing encoding information of
coding units corresponding to a coded depth, according to an
exemplary embodiment;
[0039] FIG. 9 is a diagram of deeper coding units according to
depths, according to an exemplary embodiment;
[0040] FIGS. 10 through 12 are diagrams for describing a
relationship between coding units, prediction units, and
transformation units, according to an exemplary embodiment;
[0041] FIG. 13 is a diagram for describing a relationship between a
coding unit, a prediction unit or a partition, and a transformation
unit, according to encoding mode information according to an
exemplary embodiment;
[0042] FIG. 14 is a flowchart illustrating a method of encoding a
video, according to an exemplary embodiment;
[0043] FIG. 15 is a flowchart illustrating a method of decoding a
video, according to an exemplary embodiment;
[0044] FIG. 16 is a block diagram of a video encoding apparatus
using coding unit pattern information, according to an exemplary
embodiment;
[0045] FIG. 17 is a block diagram of a video decoding apparatus
using coding unit pattern information, according to an exemplary
embodiment;
[0046] FIGS. 18 to 20 are block diagrams illustrating coding unit
pattern information corresponding to a coded depth when a coding
unit corresponding to a coded depth includes one transformation
unit, according to exemplary embodiments;
[0047] FIGS. 21 to 23 illustrate coding unit pattern information
corresponding to a coded depth when a coding unit corresponding to
the coded depth includes four transformation units, according to
exemplary embodiments;
[0048] FIGS. 24 to 26 illustrate coding unit pattern information
corresponding to a coded depth when a coding unit corresponding to
the coded depth includes a plurality of transformation units,
according to exemplary embodiments;
[0049] FIG. 27 is a diagram illustrating hierarchical coding unit
pattern information according to an exemplary embodiment;
[0050] FIG. 28 is a flowchart illustrating a method of encoding
video by using coding unit pattern information, according to an
exemplary embodiment; and
[0051] FIG. 29 is a flowchart illustrating a method of decoding
video by using coding unit pattern information, according to an
exemplary embodiment.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0052] Hereinafter, a method and apparatus for encoding video and a
method and apparatus for decoding video according to one or more
exemplary embodiments will be described with reference to the
accompanying drawings. Particularly, video encoding and decoding
performed based on coding units according to a tree structure
including spatially independent, hierarchical data units according
to one or more exemplary embodiments will be described with
reference to FIGS. 1 to 15. Also, video encoding and decoding
performed using coding unit pattern information regarding a coding
unit according to such a tree structure according to one or more
exemplary embodiments will be described in detail with reference to
FIGS. 16 to 29. In the present specification, it is understood that
expressions such as "at least one of," when preceding a list of
elements, modify the entire list of elements and do not modify the
individual elements of the list.
[0053] In the present specification, a coding unit is an encoding
data unit in which image data is encoded at an encoder side and an
encoded data unit in which the encoded image data is decoded at a
decoder side, according to exemplary embodiments. Also, a coded
depth indicates a depth where a coding unit is encoded.
[0054] In the present specification, an `image` may denote a still
image for a video or a moving image, that is, the video itself.
[0055] A method and apparatus for encoding video and a method and
apparatus for decoding video, according to one or more exemplary
embodiments, will be described with reference to FIGS. 1 to 15.
[0056] FIG. 1 is a block diagram of a video encoding apparatus 100
according to an exemplary embodiment. Referring to FIG. 1, the
video encoding apparatus 100 includes a maximum coding unit
splitter 110, a coding unit determiner 120, and an output unit
130.
[0057] The maximum coding unit splitter 110 may split a current
picture based on a maximum coding unit for the current picture of
an image. If the current picture is larger than the maximum coding
unit, image data of the current picture may be split into the at
least one maximum coding unit. The maximum coding unit according to
an exemplary embodiment may be a data unit having a size of
32.times.32, 64.times.64, 128.times.128, 256.times.256, etc.,
wherein a shape of the data unit is a square having a width and
height in squares of 2. The image data may be output to the coding
unit determiner 120 according to the at least one maximum coding
unit.
[0058] A coding unit according to an exemplary embodiment may be
characterized by a maximum size and a depth. The depth denotes a
number of times the coding unit is spatially split from the maximum
coding unit. Accordingly, as the depth deepens, deeper encoding
units according to depths may be split from the maximum coding unit
to a minimum coding unit. A depth of the maximum coding unit is an
uppermost depth and a depth of the minimum coding unit is a
lowermost depth. Since a size of a coding unit corresponding to
each depth decreases as the depth of the maximum coding unit
deepens, a coding unit corresponding to an upper depth may include
a plurality of coding units corresponding to lower depths.
[0059] As described above, the image data of the current picture is
split into one or more maximum coding units according to a maximum
size of the coding unit, and each of the maximum coding units may
include deeper coding units that are split according to depths.
Since the maximum coding unit according to an exemplary embodiment
is split according to depths, the image data of a spatial domain
included in the maximum coding unit may be hierarchically
classified according to depths.
[0060] A maximum depth and maximum size of a coding unit, which
limit the total number of times a height and width of the maximum
coding unit are hierarchically split, may be predetermined.
[0061] The coding unit determiner 120 encodes at least one split
region obtained by splitting a region of the maximum coding unit
according to depths, and determines a depth to output a finally
encoded image data according to the at least one split region. For
example, the coding unit determiner 120 determines a coded depth by
encoding the image data in the deeper coding units according to
depths, according to the maximum coding unit of the current
picture, and selecting a depth having the least encoding errors.
Thus, the encoded image data of the coding unit corresponding to
the determined coded depth is output by the coding unit determiner
120. Also, the coding units corresponding to the coded depth may be
regarded as encoded coding units.
[0062] The determined coded depth and the encoded image data
according to the determined coded depth are output to the output
unit 130.
[0063] The image data in the maximum coding unit is encoded based
on the deeper coding units corresponding to at least one depth
equal to or below the maximum depth, and results of encoding the
image data are compared based on each of the deeper coding units. A
depth having the least encoding errors may be selected after
comparing encoding errors of the deeper coding units. At least one
coded depth may be selected for each maximum coding unit.
[0064] The size of the maximum coding unit is split as a coding
unit is hierarchically split according to depths, and as the number
of coding units increases. Also, even if coding units correspond to
the same depth in one maximum coding unit, it is determined whether
to split each of the coding units corresponding to the same depth
to a lower depth by measuring an encoding error of the image data
of each coding unit, separately. Accordingly, even when image data
is included in one maximum coding unit, the image data is split to
regions according to the depths and the encoding errors may differ
according to regions in the one maximum coding unit. Thus, the
coded depths may differ according to regions in the image data.
Therefore, one or more coded depths may be determined in one
maximum coding unit, and the image data of the maximum coding unit
may be divided according to coding units of at least one coded
depth.
[0065] Accordingly, the coding unit determiner 120 may determine
coding units having a tree structure included in the maximum coding
unit. The coding units having a tree structure according to an
exemplary embodiment include coding units corresponding to a depth
determined to be the coded depth, from among all deeper coding
units included in the maximum coding unit. A coding unit of a coded
depth may be hierarchically determined according to depths in the
same region of the maximum coding unit, and may be independently
determined in different regions. Similarly, a coded depth in a
current region may be independently determined from a coded depth
in another region.
[0066] A maximum depth according to an exemplary embodiment is an
index related to a number of splitting times from a maximum coding
unit to a minimum coding unit. A first maximum depth according to
an exemplary embodiment may denote a total number of splitting
times from the maximum coding unit to the minimum coding unit. A
second maximum depth according to an embodiment of the present
invention may denote a total number of depth levels from the
maximum coding unit to the minimum coding unit. For example, when a
depth of the maximum coding unit is 0, a depth of a coding unit, in
which the maximum coding unit is split once, may be set to 1, and a
depth of a coding unit, in which the maximum coding unit is split
twice, may be set to 2. Here, if the minimum coding unit is a
coding unit in which the maximum coding unit is split four times, 5
depth levels of depths 0, 1, 2, 3 and 4 exist. In this case, the
first maximum depth may be set to 4, and the second maximum depth
may be set to 5.
[0067] Prediction encoding and transformation may be performed
according to the maximum coding unit. The prediction encoding and
the transformation may also be performed based on the deeper coding
units according to a depth equal to, or depths less than, the
maximum depth, according to the maximum coding unit. Transformation
may be performed according to a method of orthogonal transformation
or integer transformation.
[0068] Since the number of deeper coding units increases whenever
the maximum coding unit is split according to depths, encoding
including the prediction encoding and the transformation may be
performed on all of the deeper coding units generated as the depth
deepens. For convenience of description, the prediction encoding
and the transformation will now be described based on a coding unit
of a current depth, in a maximum coding unit.
[0069] The video encoding apparatus 100 may variously select a size
or shape of a data unit for encoding the image data. In order to
encode the image data, operations, such as prediction encoding,
transformation, and entropy encoding, are performed, and at this
time, the same data unit may be used for all operations or
different data units may be used for each operation.
[0070] For example, the video encoding apparatus 100 may select not
only a coding unit for encoding the image data, but also a data
unit different from the coding unit so as to perform the prediction
encoding on the image data in the coding unit.
[0071] In order to perform the prediction encoding in the maximum
coding unit, the prediction encoding may be performed based on a
coding unit corresponding to a coded depth, i.e., based on a coding
unit that is no longer split to coding units corresponding to a
lower depth. Hereinafter, the coding unit that is no longer split
and becomes a basis unit for the prediction encoding will be
referred to as a prediction unit. A partition obtained by splitting
the prediction unit may include a prediction unit or a data unit
obtained by splitting at least one of a height and a width of the
prediction unit.
[0072] For example, when a coding unit of 2N.times.2N (where N is a
positive integer) is no longer split and becomes a prediction unit
of 2N.times.2N, a size of a partition may be 2N.times.2N,
2N.times.N, N.times.2N, or N.times.N. Examples of a partition type
include symmetrical partitions that are obtained by symmetrically
splitting a height or a width of the prediction unit, partitions
obtained by asymmetrically splitting the height or the width of the
prediction unit (such as 1:n or n:1), partitions that are obtained
by geometrically splitting the prediction unit, and partitions
having arbitrary shapes.
[0073] A prediction mode of the prediction unit may be at least one
of an intra mode, a inter mode, and a skip mode. For example, the
intra mode or the inter mode may be performed on the partition of
2N.times.2N, 2N.times.N, N.times.2N, or N.times.N. Also, the skip
mode may be performed only on the partition of 2N.times.2N. The
encoding is independently performed on one prediction unit in a
coding unit, thereby selecting a prediction mode having a least
encoding error.
[0074] The video encoding apparatus 100 may also perform the
transformation on the image data in a coding unit based not only on
the coding unit for encoding the image data, but also based on a
data unit that is different from the coding unit.
[0075] In order to perform the transformation in the coding unit,
the transformation may be performed based on a data unit having a
size smaller than or equal to the coding unit. For example, the
data unit for the transformation may include a data unit for an
intra mode and a data unit for an inter mode.
[0076] A data unit used as a base of the transformation will
hereinafter be referred to as a transformation unit. A
transformation depth indicating a number of splitting times to
reach the transformation unit by splitting a height and a width of
the coding unit may also be set in the transformation unit. For
example, in a current coding unit of 2N.times.2N, a transformation
depth may be 0 when a size of a transformation unit is also
2N.times.2N, may be 1 when each of the height and the width of the
current coding unit is split into two equal parts, totally split
into 4 1 transformation units, and the size of the transformation
unit is thus N.times.N, and may be 2 when each of the height and
the width of the current coding unit is split into four equal
parts, totally split into 4 2 transformation units, and the size of
the transformation unit is thus N/2.times.N/2. For example, the
transformation unit may be set according to a hierarchical tree
structure, in which a transformation unit of an upper
transformation depth is split into four transformation units of a
lower transformation depth according to hierarchical
characteristics of a transformation depth.
[0077] Similar to the coding unit, the transformation unit in the
coding unit may be recursively split into smaller sized regions, so
that the transformation unit may be determined independently in
units of regions. Thus, residual data in the coding unit may be
divided according to the transformation having the tree structure
according to transformation depths.
[0078] Encoding information according to coding units corresponding
to a coded depth uses not only information about the coded depth,
but also information about information related to prediction
encoding and transformation. Accordingly, the coding unit
determiner 120 not only determines a coded depth having a minimum
encoding error, but also determines a partition type in a
prediction unit, a prediction mode according to prediction units,
and a size of a transformation unit for transformation.
[0079] Coding units according to a tree structure in a maximum
coding unit and a method of determining a partition, according to
one or more exemplary embodiments, will be described in detail
later with reference to FIGS. 3 through 12.
[0080] The coding unit determiner 120 may measure an encoding error
of deeper coding units according to depths by using Rate-Distortion
Optimization based on Lagrangian multipliers.
[0081] The output unit 130 outputs the image data of the maximum
coding unit, which is encoded based on the at least one coded depth
determined by the coding unit determiner 120, and information about
the encoding mode according to the coded depth, in a bitstream. The
encoded image data may be obtained by encoding residual data of an
image. The information about the encoding mode according to coded
depth may include at least one of information about the coded
depth, information about the partition type in the prediction unit,
the prediction mode, and the size of the transformation unit.
[0082] The information about the coded depth may be defined by
using split information according to depths, which indicates
whether encoding is performed on coding units of a lower depth
instead of a current depth. If the current depth of the current
coding unit is the coded depth, image data in the current coding
unit is encoded and output, and thus the split information may be
defined not to split the current coding unit to a lower depth.
Alternatively, if the current depth of the current coding unit is
not the coded depth, the encoding is performed on the coding unit
of the lower depth. Thus, the split information may be defined to
split the current coding unit to obtain the coding units of the
lower depth.
[0083] If the current depth is not the coded depth, encoding is
performed on the coding unit that is split into the coding unit of
the lower depth. Since at least one coding unit of the lower depth
exists in one coding unit of the current depth, the encoding is
repeatedly performed on each coding unit of the lower depth. Thus,
the encoding may be recursively performed for the coding units
having the same depth.
[0084] Since the coding units having a tree structure are
determined for one maximum coding unit, and information about at
least one encoding mode is determined for a coding unit of a coded
depth, information about at least one encoding mode may be
determined for one maximum coding unit. Also, a coded depth of the
image data of the maximum coding unit may be different according to
locations since the image data is hierarchically split according to
depths. Thus, information about the coded depth and the encoding
mode may be set for the image data.
[0085] Accordingly, the output unit 130 may assign encoding
information about a corresponding coded depth and an encoding mode
to at least one of the coding unit, the prediction unit, and a
minimum unit included in the maximum coding unit.
[0086] The minimum unit according to an exemplary embodiment may be
a rectangular data unit obtained by splitting the minimum coding
unit having the lowermost depth by 4. Alternatively, the minimum
unit may be a maximum rectangular data unit that may be included in
all of the coding units, prediction units, partition units, and
transformation units included in the maximum coding unit.
[0087] For example, the encoding information output through the
output unit 130 may be classified into encoding information
according to coding units, and encoding information according to
prediction units. The encoding information according to the coding
units may include at least one of information about the prediction
mode and information about a size of the partitions. The encoding
information according to the prediction units may include at least
one of information about an estimated direction of an inter mode,
information about a reference image index of the inter mode,
information about a motion vector, information about a chroma
component of an intra mode, and information about an interpolation
method of the intra mode. Also, information about a maximum size of
the coding unit defined according to pictures, slices, or groups of
pictures (GOPs), and information about a maximum depth may be
inserted into a Sequence Parameter Set (SPS) or a header of a
bitstream.
[0088] In the video encoding apparatus 100, the deeper coding unit
may be a coding unit obtained by dividing at least one of a height
and a width of a coding unit of an upper depth, which is one layer
above, by two. In other words, when the size of the coding unit of
the current depth is 2N.times.2N, the size of the coding unit of
the lower depth may be N.times.N. Also, the coding unit of the
current depth having the size of 2N.times.2N may include 4 of the
coding units of the lower depth.
[0089] Accordingly, the video encoding apparatus 100 may form the
coding units having the tree structure by determining coding units
having an optimum shape and an optimum size for each maximum coding
unit, based on the size of the maximum coding unit and the maximum
depth determined considering characteristics of the current
picture. Also, since encoding may be performed on each maximum
coding unit by using any of various prediction modes and
transformations, an optimum encoding mode may be determined
considering characteristics of the coding unit of various image
sizes.
[0090] Thus, if an image having a high resolution or a large data
amount is encoded in a related art macroblock, a number of
macroblocks per picture excessively increases. Accordingly, a
number of pieces of compressed information generated for each
macroblock increases, and thus it is difficult to transmit the
compressed information and data compression efficiency decreases.
However, by using the video encoding apparatus 100 according to an
exemplary embodiment, image compression efficiency may be increased
since a coding unit is adjusted while considering characteristics
of an image while increasing a maximum size of a coding unit while
considering a size of the image.
[0091] FIG. 2 is a block diagram of a video decoding apparatus 200,
according to an exemplary embodiment. Referring to FIG. 2, the
video decoding apparatus 200 includes a receiver 210, an image data
and encoding information extractor 220, and an image data decoder
230. Definitions of various terms, such as a coding unit, a depth,
a prediction unit, a transformation unit, and information about
various encoding modes, for various operations of the video
decoding apparatus 200 are the same or similar to those described
above with reference to FIG. 1 and the video encoding apparatus
100.
[0092] The receiver 210 receives and parses a bitstream of an
encoded video. The image data and encoding information extractor
220 extracts encoded image data for each coding unit from the
parsed bitstream, wherein the coding units have a tree structure
according to each maximum coding unit, and outputs the extracted
image data to the image data decoder 230. The image data and
encoding information extractor 220 may extract information about a
maximum size of a coding unit of a current picture from a header
corresponding to the current picture or an SPS.
[0093] Also, the image data and encoding information extractor 220
extracts information about a coded depth and an encoding mode for
the coding units having a tree structure according to each maximum
coding unit, from the parsed bitstream. The extracted information
about the coded depth and the encoding mode is output to the image
data decoder 230. Thus, the image data in a bit stream is split
into the maximum coding unit so that the image data decoder 230
decodes the image data for each maximum coding unit.
[0094] The information about the coded depth and the encoding mode
according to the maximum coding unit may be set for information
about at least one coding unit corresponding to the coded depth.
Furthermore, the information about the encoding mode may include at
least one of information about a partition type of a corresponding
coding unit corresponding to the coded depth, information about a
prediction mode, and a size of a transformation unit. Also,
splitting information according to depths may be extracted as the
information about the coded depth.
[0095] The information about the coded depth and the encoding mode
according to each maximum coding unit extracted by the image data
and encoding information extractor 220 is information about a coded
depth and an encoding mode determined to generate a minimum
encoding error when an encoder, such as the video encoding
apparatus 100, repeatedly performs encoding for each deeper coding
unit according to depths according to each maximum coding unit.
Accordingly, the video decoding apparatus 200 may restore an image
by decoding the image data according to a coded depth and an
encoding mode that generates the minimum encoding error.
[0096] Since encoding information about the coded depth and the
encoding mode may be assigned to a predetermined data unit from
among a corresponding coding unit, a prediction unit, and a minimum
unit, the image data and encoding information extractor 220 may
extract the information about the coded depth and the encoding mode
according to the predetermined data units. The predetermined data
units to which the same information about the coded depth and the
encoding mode is assigned may be inferred to be the data units
included in the same maximum coding unit.
[0097] The image data decoder 230 restores the current picture by
decoding the image data in each maximum coding unit based on the
information about the coded depth and the encoding mode according
to the maximum coding units. In other words, the image data decoder
230 may decode the encoded image data based on the extracted
information about the partition type, the prediction mode, and the
transformation unit for each coding unit from among the coding
units having the tree structure included in each maximum coding
unit. A decoding process may include at least one of a prediction
including intra prediction and motion compensation, and an inverse
transformation. Inverse transformation may be performed according
to method of inverse orthogonal transformation or inverse integer
transformation.
[0098] The image data decoder 230 may perform intra prediction or
motion compensation according to a partition and a prediction mode
of each coding unit, based on the information about the partition
type and the prediction mode of the prediction unit of the coding
unit according to coded depths.
[0099] Also, the image data decoder 230 may perform inverse
transformation according to each transformation unit in the coding
unit, based on the information about the size of the transformation
unit of the coding unit according to coded depths, so as to perform
the inverse transformation according to maximum coding units.
[0100] The image data decoder 230 may determine at least one coded
depth of a current maximum coding unit by using split information
according to depths. If the split information indicates that image
data is no longer split in the current depth, the current depth is
a coded depth. Accordingly, the image data decoder 230 may decode
encoded data of at least one coding unit corresponding to each
coded depth in the current maximum coding unit by using the
information about the partition type of the prediction unit, the
prediction mode, and the size of the transformation unit for each
coding unit corresponding to the coded depth, and output the image
data of the current maximum coding unit.
[0101] In other words, data units including the encoding
information including the same split information may be gathered by
observing the encoding information set assigned for the
predetermined data unit from among the coding unit, the prediction
unit, and the minimum unit. Moreover, the gathered data units may
be considered to be one data unit to be decoded by the image data
decoder 230 in the same encoding mode.
[0102] The video decoding apparatus 200 may obtain information
about at least one coding unit that generates the minimum encoding
error when encoding is recursively performed for each maximum
coding unit, and may use the information to decode the current
picture. In other words, the coding units having the tree structure
determined to be the optimum coding units in each maximum coding
unit may be decoded. Also, a maximum size of the coding unit may be
determined considering resolution and an amount of image data.
[0103] Accordingly, even if image data has a high resolution and a
large amount of data, the image data may be efficiently decoded and
restored by using a size of a coding unit and an encoding mode,
which are adaptively determined according to characteristics of the
image data, by using information about an optimum encoding mode
received from an encoder.
[0104] A method of determining coding units having a tree
structure, a prediction unit, and a transformation unit, according
to one or more exemplary embodiments will now be described with
reference to FIGS. 3 through 13.
[0105] FIG. 3 is a diagram for describing a concept of coding units
according to an exemplary embodiment. A size of a coding unit may
be expressed in width.times.height, and may be 64.times.64,
32.times.32, 16.times.16, and 8.times.8, though it is understood
that another exemplary embodiment is not limited thereto. A coding
unit of 64.times.64 may be split into partitions of 64.times.64,
64.times.32, 32.times.64, or 32.times.32, a coding unit of
32.times.32 may be split into partitions of 32.times.32,
32.times.16, 16.times.32, or 16.times.16, a coding unit of
16.times.16 may be split into partitions of 16.times.16,
16.times.8, 8.times.16, or 8.times.8, and a coding unit of
8.times.8 may be split into partitions of 8.times.8, 8.times.4,
4.times.8, or 4.times.4.
[0106] Referring to FIG. 3, first video data 310 has a resolution
is 1920.times.1080, a maximum size of a coding unit of 64, and a
maximum depth of 2. Second video data 320 has a resolution of
1920.times.1080, a maximum size of a coding unit of 64, and a
maximum depth of 3. Third video data 330 has a resolution of
352.times.288, a maximum size of a coding unit of 16, and a maximum
depth of 1. The maximum depth shown in FIG. 3 denotes a total
number of splits from a maximum coding unit to a minimum decoding
unit.
[0107] If a resolution is high or a data amount is large, a maximum
size of a coding unit may be large so as to not only increase
encoding efficiency but also to accurately reflect characteristics
of an image. Accordingly, the maximum size of the coding units of
the first and second video data 310 and 320 having a higher
resolution than the third video data 330 may be 64.
[0108] Since the maximum depth of the first video data 310 is 2,
coding units 315 of the first video data 310 may include a maximum
coding unit having a long axis size of 64, and coding units having
long axis sizes of 32 and 16 since depths are deepened to two
layers by splitting the maximum coding unit twice. Meanwhile, since
the maximum depth of the third video data 330 is 1, coding units
335 of the third video data 330 may include a maximum coding unit
having a long axis size of 16, and coding units having a long axis
size of 8 since depths are deepened to one layer by splitting the
maximum coding unit once.
[0109] Since the maximum depth of the second video data 320 is 3,
coding units 325 of the second video data 320 may include a maximum
coding unit having a long axis size of 64, and coding units having
long axis sizes of 32, 16, and 8 since the depths are deepened to 3
layers by splitting the maximum coding unit three times. As a depth
deepens (i.e., increases), detailed information may be precisely
expressed.
[0110] FIG. 4 is a block diagram of an image encoder 400 based on
coding units, according to an exemplary embodiment. Referring to
FIG. 4, the image encoder 400 performs operations of the coding
unit determiner 120 of the video encoding apparatus 100 to encode
image data. For example, an intra predictor 410 performs intra
prediction on coding units in an intra mode, from among a current
frame 405, and a motion estimator 420 and a motion compensator 425
perform inter estimation and motion compensation, respectively, on
coding units in an inter mode from among the current frame 405 by
using the current frame 405, and a reference frame 495.
[0111] Data output from the intra predictor 410, the motion
estimator 420, and the motion compensator 425 is output as a
quantized transformation coefficient through a transformer 430 and
a quantizer 440. The quantized transformation coefficient is
restored as data in a spatial domain through an inverse quantizer
460 and an inverse transformer 470. The restored data in the
spatial domain is output as the reference frame 495 after being
post-processed through a deblocking unit 480 and a loop filtering
unit 490. The quantized transformation coefficient may be output as
a bitstream 455 through an entropy encoder 450.
[0112] In order for the image encoder 400 to be applied in the
video encoding apparatus 100, elements of the image encoder 400,
i.e., the intra predictor 410, the motion estimator 420, the motion
compensator 425, the transformer 430, the quantizer 440, the
entropy encoder 450, the inverse quantizer 460, the inverse
transformer 470, the deblocking unit 480, and the loop filtering
unit 490, perform operations based on each coding unit from among
coding units having a tree structure while considering the maximum
depth of each maximum coding unit.
[0113] Specifically, the intra predictor 410, the motion estimator
420, and the motion compensator 425 determine partitions and a
prediction mode of each coding unit from among the coding units
having a tree structure while considering a maximum size and a
maximum depth of a current maximum coding unit, and the transformer
430 determines a size of the transformation unit in each coding
unit from among the coding units having a tree structure.
[0114] FIG. 5 is a block diagram of an image decoder 500 based on
coding units, according to an exemplary embodiment. Referring to
FIG. 5, a parser 510 parses encoded image data to be decoded and
information about encoding used for decoding from a bitstream 505.
The encoded image data is output as inverse quantized data through
an entropy decoder 520 and an inverse quantizer 530, and the
inverse quantized data is restored to image data in a spatial
domain through an inverse transformer 540.
[0115] An intra predictor 550 performs intra prediction on coding
units in an intra mode with respect to the image data in the
spatial domain, and a motion compensator 560 performs motion
compensation on coding units in an inter mode by using a reference
frame 585.
[0116] The image data in the spatial domain, which passed through
the intra predictor 550 and the motion compensator 560, may be
output as a restored frame 595 after being post-processed through a
deblocking unit 570 and a loop filtering unit 580. Also, the image
data that is post-processed through the deblocking unit 570 and the
loop filtering unit 580 may be output as the reference frame
585.
[0117] In order to decode the image data in the image data decoder
230 of the video decoding apparatus 200, the image decoder 500 may
perform operations that are performed after the parser 510.
[0118] In order for the image decoder 500 to be applied in the
video decoding apparatus 200, elements of the image decoder 500,
i.e., the parser 510, the entropy decoder 520, the inverse
quantizer 530, the inverse transformer 540, the intra predictor
550, the motion compensator 560, the deblocking unit 570, and the
loop filtering unit 580, perform operations based on coding units
having a tree structure for each maximum coding unit.
[0119] Specifically, the intra prediction 550 and the motion
compensator 560 perform operations based on partitions and a
prediction mode for each of the coding units having a tree
structure, and the inverse transformer 540 performs operations
based on a size of a transformation unit for each coding unit.
[0120] FIG. 6 is a diagram illustrating deeper coding units
according to depths, and partitions, according to an exemplary
embodiment. A video encoding apparatus 100 according to an
exemplary embodiment and a video decoding apparatus 200 according
to an exemplary embodiment use hierarchical coding units so as to
consider characteristics of an image. A maximum height, a maximum
width, and a maximum depth of coding units may be adaptively
determined according to the characteristics of the image, or may be
differently set by a user. Sizes of deeper coding units according
to depths may be determined according to a predetermined maximum
size of the coding unit.
[0121] Referring to FIG. 6, in a hierarchical structure 600 of
coding units, according to an exemplary embodiment, the maximum
height and the maximum width of the coding units are each 64, and
the maximum depth is 4. Since a depth deepens (i.e., increases)
along a vertical axis of the hierarchical structure 600, a height
and a width of the deeper coding units are each split. Also, a
prediction unit and partitions, which are bases for prediction
encoding of each deeper coding unit, are shown along a horizontal
axis of the hierarchical structure 600.
[0122] For example, a first coding unit 610 is a maximum coding
unit in the hierarchical structure 600, wherein a depth thereof is
0 and a size, i.e., a height by width, thereof is 64.times.64. The
depth deepens along the vertical axis such that the hierarchical
structure 600 includes a second coding unit 620 having a size of
32.times.32 and a depth of 1, a third coding unit 630 having a size
of 16.times.16 and a depth of 2, a fourth coding unit 640 having a
size of 8.times.8 and a depth of 3, and a fifth coding unit 650
having a size of 4.times.4 and a depth of 4. The fifth coding unit
650 having the size of 4.times.4 and the depth of 4 is a minimum
coding unit.
[0123] The prediction unit and the partitions of the coding units
610, 620, 630, 640, and 650 are arranged along the horizontal axis
according to each depth. In other words, if the first coding unit
610 having the size of 64.times.64 and the depth of 0 is a
prediction unit, the prediction unit may be split into partitions
included in the first coding unit 610, i.e. a partition 610 having
a size of 64.times.64, partitions 612 having a size of 64.times.32,
partitions 614 having a size of 32.times.64, or partitions 616
having a size of 32.times.32.
[0124] Similarly, a prediction unit of the second coding unit 620
having the size of 32.times.32 and the depth of 1 may be split into
partitions included in the second coding unit 620, i.e. a partition
620 having a size of 32.times.32, partitions 622 having a size of
32.times.16, partitions 624 having a size of 16.times.32, and
partitions 626 having a size of 16.times.16.
[0125] Similarly, a prediction unit of the third coding unit 630
having the size of 16.times.16 and the depth of 2 may be split into
partitions included in the third coding unit 630, i.e. a partition
having a size of 16.times.16 included in the third coding unit 630,
partitions 632 having a size of 16.times.8, partitions 634 having a
size of 8.times.16, and partitions 636 having a size of
8.times.8.
[0126] Similarly, a prediction unit of the fourth coding unit 640
having the size of 8.times.8 and the depth of 3 may be split into
partitions included in the fourth coding unit 640, i.e. a partition
having a size of 8.times.8 included in the fourth coding unit 640,
partitions 642 having a size of 8.times.4, partitions 644 having a
size of 4.times.8, and partitions 646 having a size of
4.times.4.
[0127] The fifth coding unit 650 having the size of 4.times.4 and
the depth of 4 is the minimum coding unit and a coding unit of the
lowermost depth. A prediction unit of the fifth coding unit 650 is
assigned to a partition having a size of 4.times.4.
[0128] In order to determine the at least one coded depth of the
coding units of the maximum coding unit 610, the coding unit
determiner 120 of the video encoding apparatus 100 performs
encoding for coding units corresponding to each depth included in
the maximum coding unit 610.
[0129] A number of deeper coding units according to depths
including data in the same range and the same size increases as the
depth deepens. For example, four coding units corresponding to a
depth of 2 are required to cover data that is included in one
coding unit corresponding to a depth of 1. Accordingly, in order to
compare encoding results of the same data according to depths, the
coding unit corresponding to the depth of 1 and four coding units
corresponding to the depth of 2 are each encoded.
[0130] In order to perform encoding for a current depth from among
the depths, a minimum encoding error may be selected for the
current depth by performing encoding for each prediction unit in
the coding units corresponding to the current depth, along the
horizontal axis of the hierarchical structure 600. Alternatively,
the minimum encoding error may be searched for by comparing the
minimum encoding errors according to depths, by performing encoding
for each depth as the depth deepens along the vertical axis of the
hierarchical structure 600. A depth and a partition having the
minimum encoding error in the first coding unit 610 may be selected
as the coded depth and a partition type of the first coding unit
610.
[0131] FIG. 7 is a diagram for describing a relationship between a
coding unit 710 and transformation units 720, according to an
exemplary embodiment. A video encoding apparatus 100 according to
an exemplary embodiment and a video decoding apparatus 200
according to an exemplary embodiment encodes and decodes,
respectively, an image according to coding units having sizes
smaller than or equal to a maximum coding unit for each maximum
coding unit. Sizes of transformation units for transformation
during encoding may be selected based on data units that are not
larger than a corresponding coding unit.
[0132] Referring to FIG. 7, for example, in the video encoding
apparatus 100, if a size of the coding unit 710 is 64.times.64,
transformation may be performed by using the transformation units
720 having a size of 32.times.32.
[0133] Also, data of the coding unit 710 having the size of
64.times.64 may be encoded by performing the transformation on each
of the transformation units having the size of 32.times.32,
16.times.16, 8.times.8, and 4.times.4, which are smaller than
64.times.64, and then a transformation unit having the least coding
errors may be selected.
[0134] FIG. 8 is a diagram for describing encoding information of
coding units corresponding to a coded depth, according to an
exemplary embodiment. Referring to FIG. 8, the output unit 130 of a
video encoding apparatus 100 according to an exemplary embodiment
may encode and transmit first information 800 about a partition
type, second information 810 about a prediction mode, and third
information 820 about a size of a transformation unit for each
coding unit corresponding to a coded depth, as information about an
encoding mode.
[0135] The first information 800 indicates information about a
shape of a partition obtained by splitting a prediction unit of a
current coding unit, wherein the partition is a data unit for
prediction encoding the current coding unit. For example, a current
coding unit CU.sub.--0 having a size of 2N.times.2N may be split
into any one of a partition 802 having a size of 2N.times.2N, a
partition 804 having a size of 2N.times.N, a partition 806 having a
size of N.times.2N, and a partition 808 having a size of N.times.N.
Here, the first information 800 about a partition type is set to
indicate one of the partition 804 having a size of 2N.times.N, the
partition 806 having a size of N.times.2N, and the partition 808
having a size of N.times.N
[0136] The second information 810 indicates a prediction mode of
each partition. For example, the second information 810 may
indicate a mode of prediction encoding performed on a partition
indicated by the first information 800, i.e., an intra mode 812, an
inter mode 814, or a skip mode 816.
[0137] The third information 820 indicates a transformation unit to
be based on when transformation is performed on a current coding
unit. For example, the transformation unit may be a first intra
transformation unit 822, a second intra transformation unit 824, a
first inter transformation unit 826, or a second intra
transformation unit 828.
[0138] An image data and encoding information extractor 220 of a
video decoding apparatus 200 according to an exemplary embodiment
may extract and use the information 800, 810, and 820 for decoding,
according to each deeper coding unit
[0139] FIG. 9 is a diagram of deeper coding units according to
depths, according to an exemplary embodiment. Split information may
be used to indicate a change of a depth. The spilt information
indicates whether a coding unit of a current depth is split into
coding units of a lower depth.
[0140] Referring to FIG. 9, a prediction unit 910 for prediction
encoding a coding unit 900 having a depth of 0 and a size of
2N.sub.--0.times.2N.sub.--0 may include partitions of a partition
type 912 having a size of 2N.sub.--0.times.2N.sub.--0, a partition
type 914 having a size of 2N.sub.--0.times.N.sub.--0, a partition
type 916 having a size of N.sub.--0.times.2N.sub.--0, and a
partition type 918 having a size of N.sub.--0.times.N.sub.--0. FIG.
9 only illustrates the partition types 912 through 918 which are
obtained by symmetrically splitting the prediction unit 910, but it
is understood that a partition type is not limited thereto in
another exemplary embodiment. For example, according to another
exemplary embodiment, the partitions of the prediction unit 910 may
include asymmetrical partitions, partitions having a predetermined
shape, and partitions having a geometrical shape.
[0141] Prediction encoding is repeatedly performed on one partition
having a size of 2N.sub.--0.times.2N.sub.--0, two partitions having
a size of 2N.sub.--0.times.N.sub.--0, two partitions having a size
of N.sub.--0.times.2N.sub.--0, and four partitions having a size of
N.sub.--0.times.N.sub.--0, according to each partition type. The
prediction encoding in an intra mode and an inter mode may be
performed on the partitions having the sizes of
2N.sub.--0.times.2N.sub.--0, N.sub.--0.times.2N.sub.--0,
2N.sub.--0.times.N.sub.--0, and N.sub.--0.times.N.sub.--0. The
prediction encoding in a skip mode is performed only on the
partition having the size of 2N.sub.--0.times.2N.sub.--0.
[0142] Errors of encoding including the prediction encoding in the
partition types 912 through 918 are compared, and the minimum
encoding error is determined among the partition types. If an
encoding error is smallest in one of the partition types 912
through 916, the prediction unit 910 may not be split into a lower
depth.
[0143] If the encoding error is the smallest in the partition type
918, a depth is changed from 0 to 1 to split the partition type 918
in operation 920, and encoding is repeatedly performed on coding
units 930 having a depth of 2 and a size of
N.sub.--0.times.N.sub.--0 to search for a minimum encoding
error.
[0144] A prediction unit 940 for prediction encoding the coding
unit 930 having a depth of 1 and a size of
2N.sub.--1.times.2N.sub.--1 (=N.sub.--0.times.N.sub.--0) may
include partitions of a partition type 942 having a size of
2N.sub.--1.times.2N.sub.--1, a partition type 944 having a size of
2N.sub.--1.times.N.sub.--1, a partition type 946 having a size of
N.sub.--1.times.2N.sub.--1, and a partition type 948 having a size
of N.sub.--1.times.N.sub.--1.
[0145] If an encoding error is the smallest in the partition type
948, a depth is changed from 1 to 2 to split the partition type 948
in operation 950, and encoding is repeatedly performed on coding
units 960, which have a depth of 2 and a size of
N.sub.--2.times.N.sub.--2 to search for a minimum encoding
error.
[0146] When a maximum depth is d, split operations according to
each depth may be performed up to when a depth becomes d-1, and
split information may be encoded up to when a depth is one of 0 to
d-2. For example, when encoding is performed up to when the depth
is d-1 after a coding unit corresponding to a depth of d-2 is split
in operation 970, a prediction unit 990 for prediction encoding a
coding unit 980 having a depth of d-1 and a size of
2N_(d-1).times.2N_(d-1) may include partitions of a partition type
992 having a size of 2N_(d-1).times.2N_(d-1), a partition type 994
having a size of 2N_(d-1).times.N_(d-1), a partition type 996
having a size of N_(d-1).times.2N_(d-1), and a partition type 998
having a size of N_(d-1).times.N_(d-1).
[0147] Prediction encoding may be repeatedly performed on one
partition having a size of 2N_(d-1).times.2N_(d-1), two partitions
having a size of 2N_(d-1).times.N_(d-1), two partitions having a
size of N_(d-1).times.2N_(d-1), four partitions having a size of
N_(d-1).times.N_(d-1) from among the partition types 992 through
998 to search for a partition type having a minimum encoding
error.
[0148] Even when the partition type 998 has the minimum encoding
error, since a maximum depth is d, a coding unit CU_(d-1) having a
depth of d-1 is no longer split to a lower depth, and a coded depth
for the coding units of a current maximum coding unit 900 is
determined to be d-1 and a partition type of the current maximum
coding unit 900 may be determined to be N_(d-1).times.N_(d-1).
Also, since the maximum depth is d and a minimum coding unit 980
having a lowermost depth of d-1 is no longer split to a lower
depth, split information for the minimum coding unit 980 is not
set.
[0149] A data unit 999 may be considered a minimum unit for the
current maximum coding unit. A minimum unit according to an
exemplary embodiment may be a rectangular data unit obtained by
splitting a minimum coding unit 980 by 4. By performing the
encoding repeatedly, a video encoding apparatus 100 according to an
exemplary embodiment may select a depth having the minimum encoding
error by comparing encoding errors according to depths of the
coding unit 900 to determine a coded depth, and set a corresponding
partition type and a prediction mode as an encoding mode of the
coded depth.
[0150] As such, the minimum encoding errors according to depths are
compared in all of the depths of 1 through d, and a depth having
the least encoding errors may be determined as a coded depth. At
least one of the coded depth, the partition type of the prediction
unit, and the prediction mode may be encoded and transmitted as
information about an encoding mode. Also, since a coding unit is
split from a depth of 0 to a coded depth, only split information of
the coded depth is set to 0, and split information of depths
excluding the coded depth are set to 1.
[0151] An image data and encoding information extractor 220 of a
video decoding apparatus 200 according to an exemplary embodiment
may extract and use the information about the coded depth and the
prediction unit of the coding unit 900 to decode the partition 912.
The video decoding apparatus 200 may determine a depth, in which
split information is 0, as a coded depth by using split information
according to depths, and use information about an encoding mode of
the corresponding depth for decoding.
[0152] FIGS. 10 through 12 are diagrams for describing a
relationship between coding units 1010, prediction units 1060, and
transformation units 1070, according to an exemplary
embodiment.
[0153] Referring to FIGS. 10 through 12, the coding units 1010 are
coding units having a tree structure, corresponding to coded depths
determined by a video encoding apparatus 100 according to an
exemplary embodiment, in a maximum coding unit. The prediction
units 1060 are partitions of prediction units of each of the coding
units 1010, and the transformation units 1070 are transformation
units of each of the coding units 1010.
[0154] When a depth of a maximum coding unit is 0 in the coding
units 1010, depths of coding units 1012 and 1054 are 1, depths of
coding units 1014, 1016, 1018, 1028, 1050, and 1052 are 2, depths
of coding units 1020, 1022, 1024, 1026, 1030, 1032, and 1048 are 3,
and depths of coding units 1040, 1042, 1044, and 1046 are 4.
[0155] In the prediction units 1060, some encoding units 1014,
1016, 1022, 1032, 1048, 1050, 1052, and 1054 are obtained by
splitting the coding units of the coding units 1010. For example,
partition types in the coding units 1014, 1022, 1050, and 1054 have
a size of 2N.times.N, partition types in the coding units 1016,
1048, and 1052 have a size of N.times.2N, and a partition type of
the coding unit 1032 has a size of N.times.N. Prediction units and
partitions of the coding units 1010 are smaller than or equal to
each coding unit.
[0156] Transformation or inverse transformation is performed on
image data of the coding unit 1052 in the transformation units 1070
in a data unit that is smaller than the coding unit 1052. Also, the
coding units 1014, 1016, 1022, 1032, 1048, 1050, and 1052 in the
transformation units 1070 are different from those in the
prediction units 1060 in terms of sizes and shapes. For example,
video encoding and decoding apparatuses 100 and 200 according to
exemplary embodiments may perform intra prediction, motion
estimation, motion compensation, transformation, and inverse
transformation individually on a data unit in the same coding
unit.
[0157] Accordingly, encoding is recursively performed on each of
coding units having a hierarchical structure in each region of a
maximum coding unit to determine an optimum coding unit, and thus
coding units having a recursive tree structure may be obtained.
Encoding information may include at least one of split information
about a coding unit, information about a partition type,
information about a prediction mode, and information about a size
of a transformation unit. Table 1 shows exemplary encoding
information that may be set by the video encoding and decoding
apparatuses 100 and 200.
TABLE-US-00001 TABLE 1 Split Information 0 (Encoding on Coding Unit
having Size of 2N .times. 2N and Current Depth of d) Size of
Transformation Unit Partition Split Split Type Information 0
Information 1 Symmetrical Asymmetrical of of Prediction Partition
Partition Transformation Transformation Split Mode Type Type Unit
Unit Information 1 Intra 2N .times. 2N 2N .times. nU 2N .times. 2N
N .times. N Repeatedly Inter 2N .times. N 2N .times. nD
(Symmetrical Encode Skip N .times. 2N nL .times. 2N Type) Coding
Units (Only N .times. N nR .times. 2N N/2 .times. N/2 having 2N
.times. 2N) (Asymmetrical Lower Depth Type) of d + 1
[0158] An output unit 130 of the video encoding apparatus 100 may
output the encoding information about the coding units having a
tree structure, and an image data and encoding information
extractor 220 of the video decoding apparatus 200 may extract the
encoding information about the coding units having a tree structure
from a received bitstream.
[0159] Split information indicates whether a current coding unit is
split into coding units of a lower depth. If split information of a
current depth d is 0, a depth in which a current coding unit is no
longer split into a lower depth is a coded depth, and thus
information about a partition type, prediction mode, and a size of
a transformation unit may be defined for the coded depth. If the
current coding unit is further split according to the split
information, encoding is independently performed on four split
coding units of a lower depth.
[0160] A prediction mode may be one of an intra mode, an inter
mode, and a skip mode. The intra mode and the inter mode may be
defined in all partition types, and the skip mode may be defined
only in a partition type having a size of 2N.times.2N.
[0161] The information about the partition type may indicate
symmetrical partition types having sizes of 2N.times.2N,
2N.times.N, N.times.2N, and N.times.N, which are obtained by
symmetrically splitting at least one of a height and a width of a
prediction unit, and asymmetrical partition types having sizes of
2N.times.nU, 2N.times.nD, nL.times.2N, and nR.times.2N, which are
obtained by asymmetrically splitting at least one of the height and
the width of the prediction unit. The asymmetrical partition types
having the sizes of 2N.times.nU and 2N.times.nD may be respectively
obtained by splitting the height of the prediction unit in 1:3 and
3:1, and the asymmetrical partition types having the sizes of
nL.times.2N and nR.times.2N may be respectively obtained by
splitting the width of the prediction unit in 1:3 and 3:1
[0162] The size of the transformation unit may be set to be two
types in the intra mode and two types in the inter mode. For
example, if split information of the transformation unit is 0, the
size of the transformation unit may be 2N.times.2N, which is the
size of the current coding unit. If split information of the
transformation unit is 1, the transformation units may be obtained
by splitting the current coding unit. Also, if a partition type of
the current coding unit having the size of 2N.times.2N is a
symmetrical partition type, a size of a transformation unit may be
N.times.N, and if the partition type of the current coding unit is
an asymmetrical partition type, the size of the transformation unit
may be N/2.times.N/2.
[0163] The encoding information about coding units having a tree
structure may include at least one of a coding unit corresponding
to a coded depth, a prediction unit, and a minimum unit. The coding
unit corresponding to the coded depth may include at least one of a
prediction unit and a minimum unit including the same encoding
information.
[0164] Accordingly, it is determined whether adjacent data units
are included in the same coding unit corresponding to the coded
depth by comparing encoding information of the adjacent data units.
Also, a corresponding coding unit corresponding to a coded depth is
determined by using encoding information of a data unit, and thus a
distribution of coded depths in a maximum coding unit may be
determined.
[0165] Therefore, if a current coding unit is predicted based on
encoding information of adjacent data units, encoding information
of data units in deeper coding units adjacent to the current coding
unit may be directly referred to and used.
[0166] Alternatively, if a current coding unit is predicted based
on encoding information of adjacent data units, data units adjacent
to the current coding unit are searched using encoding information
of the data units, and the searched adjacent coding units may be
referred to for predicting the current coding unit.
[0167] FIG. 13 is a diagram for describing a relationship between a
coding unit, a prediction unit or a partition, and a transformation
unit, according to encoding mode information of Table 1 according
to an exemplary embodiment. Referring to FIG. 13, a maximum coding
unit 1300 includes coding units 1302, 1304, 1306, 1312, 1314, 1316,
and 1318 of coded depths. Here, since the coding unit 1318 is a
coding unit of a coded depth, split information may be set to 0.
Information about a partition type of the coding unit 1318 having a
size of 2N.times.2N may be set to be one of a partition type 1322
having a size of 2N.times.2N, a partition type 1324 having a size
of 2N.times.N, a partition type 1326 having a size of N.times.2N, a
partition type 1328 having a size of N.times.N, a partition type
1332 having a size of 2N.times.nU, a partition type 1334 having a
size of 2N.times.nD, a partition type 1336 having a size of
nL.times.2N, and a partition type 1338 having a size of
nR.times.2N.
[0168] When the partition type is set to be symmetrical, i.e., the
partition type 1322, 1324, 1326, or 1328, a transformation unit
1342 having a size of 2N.times.2N is set if split information (TU
size flag) of a transformation unit is 0, and a transformation unit
1344 having a size of N.times.N is set if a TU size flag is 1.
[0169] When the partition type is set to be asymmetrical, i.e., the
partition type 1332, 1334, 1336, or 1338, a transformation unit
1352 having a size of 2N.times.2N is set if a TU size flag is 0,
and a transformation unit 1354 having a size of N/2.times.N/2 is
set if a TU size flag is 1.
[0170] Referring to FIG. 13, the TU size flag is a flag having a
value or 0 or 1, though it is understood that another exemplary
embodiment is not limited to a 1-bit flag. For example, a
transformation unit may be hierarchically split having a tree
structure while the TU size flag increases from 0 in another
exemplary embodiment.
[0171] In this case, the size of a transformation unit that has
been actually used may be expressed by using a TU size flag of a
transformation unit, according to an exemplary embodiment, together
with a maximum size and minimum size of the transformation unit.
According to an exemplary embodiment, a video encoding apparatus
100 may encode maximum transformation unit size information,
minimum transformation unit size information, and a maximum TU size
flag. The result of encoding the maximum transformation unit size
information, the minimum transformation unit size information, and
the maximum TU size flag may be inserted into an SPS. According to
an exemplary embodiment, a video decoding apparatus 200 may decode
video by using the maximum transformation unit size information,
the minimum transformation unit size information, and the maximum
TU size flag.
[0172] For example, if the size of a current coding unit is
64.times.64 and a maximum transformation unit size is 32.times.32,
the size of a transformation unit may be 32.times.32 when a TU size
flag is 0, may be 16.times.16 when the TU size flag is 1, and may
be 8.times.8 when the TU size flag is 2.
[0173] As another example, if the size of the current coding unit
is 32.times.32 and a minimum transformation unit size is
32.times.32, the size of the transformation unit may be 32.times.32
when the TU size flag is 0. Here, the TU size flag cannot be set to
a value other than 0, since the size of the transformation unit
cannot be less than 32.times.32.
[0174] As another example, if the size of the current coding unit
is 64.times.64 and a maximum TU size flag is 1, the TU size flag
may be 0 or 1. Here, the TU size flag cannot be set to a value
other than 0 or 1.
[0175] Thus, if it is defined that the maximum TU size flag is
MaxTransformSizeIndex, a minimum transformation unit size is
MinTransformSize, and a transformation unit size is RootTuSize when
the TU size flag is 0, then a current minimum transformation unit
size CurrMinTuSize that can be determined in a current coding unit,
may be defined by Equation (1):
CurrMinTuSize=max(MinTransformSize,RootTuSize/(2
MaxTransformSizeIndex)) (1).
[0176] Compared to the current minimum transformation unit size
CurrMinTuSize that can be determined in the current coding unit, a
transformation unit size RootTuSize when the TU size flag is 0 may
denote a maximum transformation unit size that can be selected in
the system. In Equation (1), RootTuSize/(2 MaxTransformSizeIndex)
denotes a transformation unit size when the transformation unit
size RootTuSize, when the TU size flag is 0, is split a number of
times corresponding to the maximum TU size flag, and
MinTransformSize denotes a minimum transformation size. Thus, a
smaller value from among RootTuSize/(2 MaxTransformSizeIndex) and
MinTransformSize may be the current minimum transformation unit
size CurrMinTuSize that can be determined in the current coding
unit.
[0177] According to an exemplary embodiment, the maximum
transformation unit size RootTuSize may vary according to the type
of a prediction mode. For example, if a current prediction mode is
an inter mode, then RootTuSize may be determined by using Equation
(2) below. In Equation (2), MaxTransformSize denotes a maximum
transformation unit size, and PUSize denotes a current prediction
unit size:
RootTuSize=min(MaxTransformSize,PUSize) (2).
[0178] That is, if the current prediction mode is the inter mode,
the transformation unit size RootTuSize when the TU size flag is 0
may be a smaller value from among the maximum transformation unit
size and the current prediction unit size:
[0179] If a prediction mode of a current partition unit is an intra
mode, RootTuSize may be determined by using Equation (3) below. In
Equation (3), PartitionSize denotes the size of the current
partition unit:
RootTuSize=min(MaxTransformSize,PartitionSize) (3).
[0180] That is, if the current prediction mode is the intra mode,
the transformation unit size RootTuSize when the TU size flag is 0
may be a smaller value from among the maximum transformation unit
size and the size of the current partition unit.
[0181] However, the current maximum transformation unit size
RootTuSize that varies according to the type of a prediction mode
in a partition unit is just an example, and it is understood that
another exemplary embodiment is not limited thereto.
[0182] FIG. 14 is a flowchart illustrating a method of encoding a
video, according to an exemplary embodiment. Referring to FIG. 14,
in operation 1210, a current picture is split into at least one
maximum coding unit. A maximum depth indicating a total number of
possible splitting times may be predetermined.
[0183] In operation 1220, a coded depth to output a final encoding
result according to at least one split region, which is obtained by
splitting a region of each maximum coding unit according to depths,
is determined by encoding the at least one split region, and a
coding unit according to a tree structure is determined.
[0184] The maximum coding unit is spatially split whenever the
depth deepens, and thus is split into coding units of a lower
depth. Each coding unit may be split into coding units of another
lower depth by being spatially split independently from adjacent
coding units. Encoding is repeatedly performed on each coding unit
according to depths.
[0185] Also, a transformation unit according to partition types
having a minimum encoding error is determined for each deeper
coding unit. In order to determine a coded depth having the minimum
encoding error in each maximum coding unit, encoding errors may be
measured and compared in all deeper coding units according to
depths.
[0186] In operation 1230, encoded image data corresponding to the
final encoding result according to the coded depth is output for
each maximum coding unit, with encoding information about the coded
depth and an encoding mode. The information about the encoding mode
may include at least one of information about a coded depth or
split information, information about a partition type of a
prediction unit, a prediction mode, and a size of a transformation
unit. The encoding information about the encoding mode may be
transmitted to a decoder with the encoded image data.
[0187] FIG. 15 is a flowchart illustrating a method of decoding a
video, according to an exemplary embodiment. Referring to FIG. 15,
in operation 1310, a bitstream of an encoded video is received and
parsed.
[0188] In operation 1320, encoded image data of a current picture
assigned to a maximum coding unit, and information about a coded
depth and an encoding mode according to maximum coding units are
extracted from the parsed bitstream. The coded depth of each
maximum coding unit is a depth having a minimum encoding error in
each maximum coding unit. In encoding each maximum coding unit, the
image data is encoded based on at least one data unit obtained by
hierarchically splitting the maximum coding unit according to
depths.
[0189] According to the information about the coded depth and the
encoding mode, the maximum coding unit may be split into coding
units having a tree structure. Each of the coding units having the
tree structure is determined as a coding unit corresponding to a
coded depth, and is optimally encoded as to output the least
encoding errors. Accordingly, encoding and decoding efficiency of
an image may be improved by decoding each piece of encoded image
data in the coding units after determining at least one coded depth
according to coding units.
[0190] In operation 1330, the image data of each maximum coding
unit is decoded based on the information about the coded depth and
the encoding mode according to the maximum coding units. For
example, the decoded image data may be reproduced by a reproducing
apparatus, stored in a storage medium, or transmitted through a
network.
[0191] Now, video encoding and decoding performed using coding unit
pattern information regarding a coding unit according to a tree
structure, according to another exemplary embodiment of, will be
described in detail with reference to FIGS. 16 to 29.
[0192] FIG. 16 is a block diagram of a video encoding apparatus
1400 using coding unit pattern information, according to an
exemplary embodiment. Referring to FIG. 16, the video encoding
apparatus 1400 includes a maximum coding unit splitter 1410, a
coded unit determiner 1420, and an output unit 1460. The output
unit 1460 includes an encoded image data output unit 1430, an
encoding information output unit 1440, and a coding unit pattern
information output unit 1450.
[0193] The maximum coding unit splitter 1410 and the coded unit
determiner 1420 correspond to the maximum coding unit splitter 110
and the coded unit determiner 120 included in the video encoding
apparatus 100 illustrated in FIG. 1, respectively. The operations
of the encoded image data output unit 1430 and the encoding
information output unit 1440 may be the same as or similar to at
least some of the operations of the output unit 130 included in the
video encoding apparatus 100 of FIG. 1. An exemplary embodiment in
which the coding unit pattern information output unit 1450 encodes
coding unit pattern information will now be described.
[0194] In the current exemplary embodiment, the maximum coding unit
splitter 1410 splits a current picture of an image, based on a
maximum coding unit for the current picture. The coded unit
determiner 1420 determines at least one coded depth by encoding
image data in coding units according to depths in each maximum
coding unit and selecting a depth having the least encoding errors.
Thus, the coded unit determiner 1420 may determine coding units
having a tree structure included in each maximum coding unit.
[0195] The encoded image data output unit 1430 outputs a bitstream
of the image data encoded according to the coded depth in each
maximum coding unit. The encoding information output unit 1440
encodes and outputs information regarding encoding modes according
to coded depths in each maximum coding unit.
[0196] The coding unit pattern information output unit 1450 encodes
and outputs coding unit pattern information indicating whether
texture information for each of the maximum coding units has been
encoded. The texture information includes, for example, at least
one of a quantization parameter, a transformation coefficient, and
a transformation index for a data unit.
[0197] If the video encoding apparatus 1400 according to the
current exemplary embodiment corresponds to the image encoder 400
of FIG. 4, then motion estimated/compensated data is generated from
image data corresponding to a current coding unit by using the
intra predictor 410, the motion estimator 420, and the motion
compensator 425 of FIG. 4. The motion estimated/compensated data is
transformed by the transformer 430 and is then quantized by the
quantizer 440, thereby generating a transformation coefficient of
the current coding unit.
[0198] The coding unit pattern information regarding the current
coding unit may be set based on whether all transformation
coefficients of the current coding unit are 0. The transformation
coefficients of the current coding unit that are set to be encoded
according to the coding unit pattern information may be input to
the entropy encoder 450 to be output in a bitstream.
[0199] The coding unit pattern information is used so as to
determine whether encoded texture is to be transmitted when the
texture information is not to be encoded in coding units or when
the texture information is to be encoded in coding units. For
example, if all transformation coefficients in the coding units are
0, then the coding unit pattern information is set so as to
indicate that the texture information is not to be encoded.
However, if any one of the transformation coefficients in the
coding unit is not 0, then the coding unit pattern information is
set so as to indicate that the texture information has been
encoded.
[0200] According to an exemplary embodiment, examples of the coding
unit pattern information include coding unit pattern information
corresponding to a coded depth, and hierarchical coding unit
pattern information.
[0201] The coding unit pattern information corresponding to a coded
depth is set for coding units corresponding to at least one coded
depth in a maximum coding unit, and indicates whether texture
information of a coding unit corresponding to a coded depth has
been encoded. For example, the coding unit pattern information
corresponding to a coded depth may indicate whether all
transformation coefficients in coding units according to depths up
to a coded depth, are 0.
[0202] Hierarchical coding unit pattern information is set for at
least one transformation depth, respectively. A transformation
depth of a maximum transformation unit is an uppermost
transformation depth, and a transformation unit splits as a
transformation depth becomes deeper. Also, a transformation unit of
a current transformation depth may include four transformation
units, the depths of which are lower by one layer than the current
transformation depth.
[0203] Hierarchical coding unit pattern information corresponding
to a current transformation depth indicates whether hierarchical
coding unit pattern information regarding transformation units of
the one-layer lower depths have been encoded. The coding unit
pattern information output unit 1450 sets and encodes hierarchical
coding unit pattern information for each of transformation depths
ranging from an uppermost transformation depth to a lowermost
transformation depth or to a predetermined depth.
[0204] For example, hierarchical coding unit pattern information
may be set for each of transformation depths, and texture
information of a transformation unit corresponding to the lowermost
transformation depth may be encoded.
[0205] A transformation depth of a transformation unit may be
linked to a depth and a coded depth of a corresponding coding unit.
For example, a transformation depth may be set to be fixedly equal
to or lower by one layer than a depth of a coding unit. Otherwise,
a transformation depth may be set to be different from a depth of a
coding unit.
[0206] According to an exemplary embodiment, in the video encoding
apparatus 1400, whether only one of or both the coding unit pattern
information corresponding to a coded depth and the hierarchical
coding unit pattern information are to be encoded may be
selectively set in at least one data unit selected from among a
GOP, a picture, a slice, and a maximum coding unit.
[0207] For example, if both the coding unit pattern information
corresponding to a coded depth and the hierarchical coding unit
pattern information are used, then the coding unit pattern
information output unit 1450 may set hierarchical coding unit
pattern information for each of depths ranging from an uppermost
depth to a current coded depth, and may set and encode coding unit
pattern information corresponding to a coded depth for a coding
unit corresponding to the current coded depth.
[0208] The coding unit corresponding to the coded depth may include
at least one transformation unit. Transformation unit pattern
information indicating whether texture information has been
encoded, may be set for the at least one transformation unit,
respectively. For example, the transformation unit pattern
information indicates whether a current transformation unit
includes a transformation coefficient other than 0.
[0209] When texture information of transformation units is to be
encoded, the coding unit pattern information output unit 1450 may
set transformation unit pattern information for each of the
transformation units, and may set and encode coding unit pattern
information corresponding to a coded depth of a coding unit that
includes the transformation units.
[0210] If all the transformation coefficients in the encoding unit
of the coded depth are not 0, then the encoded image data output
unit 1430 may not output encoded texture information. According to
an exemplary embodiment, if all transformation units belonging to a
coding unit corresponding to the coded depth do not include
transformation coefficients other than 0, then the coding unit
pattern information output unit 1450 does not encode the
transformation unit pattern information for the coding unit
corresponding to the coded depth. Rather, the coding unit pattern
information output unit 1450 may set and encode coding unit pattern
information corresponding to a coded depth, which indicates the
texture information of the coding unit corresponding to the coded
depth is not to be encoded, for the coding unit corresponding to
the coded depth.
[0211] The coding unit pattern information corresponding to the
coded depth may be set according to color components of the image
data. For example, the coding unit pattern information
corresponding to the coded depth may be set for both of a luma
component and a chroma component, or may be set for each of the
luma component, the chroma component, a first chroma component, and
a second chroma component (see FIGS. 18 to 26 for a more detailed
description).
[0212] Coding unit pattern information to which one or more bits
are assigned may be set in one of coding units according to depths
and transformation units for each of maximum coding units.
[0213] FIG. 17 is a block diagram of a video decoding apparatus
1500 using coding unit pattern information, according to an
exemplary embodiment. Referring to FIG. 17, the video decoding
apparatus 1500 includes a receiver 1501, an extractor 1505, and an
image data decoder 1540. The extractor 1505 includes an image data
obtaining unit 1510, a encoding information extractor 1520, and a
coding unit pattern information extractor 1530.
[0214] The receiver 1501 and the image data decoder 1540 correspond
to the receiver 210 and the image data decoder 230 included in the
video decoding apparatus 200 of FIG. 2, respectively. The
operations of the image data obtaining unit 1510, the encoding
information extractor 1520, and the image data decoder 1540 are the
same as or similar to at least some of the operations of the image
data and encoding information extractor 220 of the video decoding
apparatus 200 of FIG. 2. A method of performing decoding by using
coding unit pattern information extracted by the coding unit
pattern information extractor 1530 according to an exemplary
embodiment will now be described with reference to FIG. 17.
[0215] The receiver 1501 receives and parses a bitstream of encoded
video. The extractor 1505 extracts various types of encoding
information from the result of parsing the bitstream. The image
data obtaining unit 1510 may obtain image data that has been
encoded in units of maximum coding units, from the result of
parsing the bitstream. The encoding information extractor 1520
parses the bitstream and then extracts information regarding a
coded depth and a encoding mode for each of the maximum coding
units, from a header of a current picture.
[0216] The coding unit pattern information extractor 1530 extracts
coding unit pattern information indicating whether texture
information of a maximum coding unit has been encoded, for each of
the maximum coding units. The coding unit pattern information
extractor 1530 may extract coding unit pattern information
corresponding to a coded depth and hierarchical coding unit pattern
information regarding a current maximum coding unit, as the coding
unit pattern information.
[0217] Whether only one of or both the coding unit pattern
information corresponding to a coded depth and the hierarchical
coding unit pattern information are to be extracted may be set in
units of a GOP, a picture, a slice, or a maximum coding unit.
[0218] For example, one unit of coding unit pattern information
corresponding to a coded depth may be extracted with respect to one
coding unit according to a coded depth, or one unit of hierarchical
coding unit pattern information may be extracted with respect to
each of depths ranging from an uppermost depth to the coded depth.
One unit of the coding unit pattern information may be
predetermined bits. For each of the maximum coding units, one or
more bits of coding unit pattern information may be set in either
coding units according to depths or a transformation unit. For
example, if the coding unit pattern information is in the form of
flags, then one unit of the coding unit pattern information may be
one bit.
[0219] The image data decoder 1540 reconstructs the current picture
by decoding the image data that has been encoded in units of
maximum coding units, based on the information regarding coded
depths and encoding modes of the maximum coding units and the
coding unit pattern information.
[0220] According to an exemplary embodiment, the image data decoder
1540 may check at least one coded depth of the current maximum
coding unit, and may detect hierarchical structures of coding units
according to depths of a tree structure included in the current
maximum coding unit, based on the information regarding coded
depths and encoding modes of the maximum coding units.
[0221] Also, the image data decoder 1540 may decode the encoded
image data by performing an inverse transformation on a
transformation coefficient included in the texture information of
the maximum coding unit extracted by the coding unit pattern
information extractor 1530, based on the coding unit pattern
information regarding the maximum coding unit.
[0222] If the image data decoder 1540 corresponds to the image
decoder 500 of FIG. 5, then the transformation coefficient included
in the texture information of coding units may be inversely
transformed into time-domain data by using the inverse quantizer
530 and the inverse transformer 540.
[0223] That is, if the coding unit pattern information indicates
that the texture information of the current coding unit has been
encoded according to the coding unit pattern information, then the
image data decoder 1540 may receive a transformation coefficient
that has been entropy decoded from the entropy decoder 520 of the
image decoder 500 of FIG. 5, and perform inverse transformation on
the transformation coefficient to obtain spatial-domain data.
Time-domain data may be reconstructed into a reconstructed frame by
using the intra predictor 550, the motion compensator 560, the
deblocking unit 570, and the loop filtering unit 580 of the image
decoder 500 of FIG. 5.
[0224] The coding unit pattern information extractor 1530 may
detect at least one of coding pattern information of a coded depth
and hierarchical coding pattern information, as coding unit pattern
information regarding coding units according to coded depths for
the current maximum coding unit.
[0225] If the coding pattern information according to a coded depth
is detected, then the image data decoder 1540 may determine a
method of decoding the coding unit corresponding to the current
coded depth, based on the detected coding pattern information
according to a coded depth.
[0226] For example, if it is determined based on the detected
coding pattern information according to a coded depth that texture
information of the coding unit corresponding to the current coded
depth has not been encoded, then the image data decoder 1540 may
decode the coding unit corresponding to the current coded depth by
referring to information regarding a data unit adjacent to the
coding unit corresponding to the current coded depth.
[0227] Also, if it is determined based on the detected coding
pattern information according to a coded depth that the texture
information of the coding unit corresponding to the current coded
depth has been encoded, then the image data decoder 1540 may decode
the coding unit corresponding to the current coded depth by
performing inverse transformation on a transformation coefficient
included in the encoded texture information of the coding unit
corresponding to the current coded depth.
[0228] Furthermore, if the hierarchical coding pattern information
is detected, the image data decoder 1540 may determine whether
hierarchical coding pattern information regarding a lower
transformation depth of a current transformation depth is present,
and determine a method of decoding a transformation unit
corresponding to the current transformation depth based on the
detected hierarchical coding unit pattern information.
[0229] For example, if it is determined based on the detected
hierarchical coding unit pattern information corresponding to the
current transformation unit corresponding to the transformation
depth that hierarchical coding pattern information regarding the
lower depth of the current transformation depth is present, then
the image data decoder 1540 may check the hierarchical coding
pattern information regarding the lower transformation depth.
However, if it is determined based on the detected hierarchical
coding unit pattern information corresponding to the current
transformation unit that hierarchical coding pattern information
regarding the lower depth of the current transformation depth is
not present, then the image data decoder 1540 may decode the
current transformation unit corresponding to the current
transformation depth.
[0230] If both the coding unit pattern information corresponding to
a coded depth and the hierarchical coding unit pattern information
are detected, then the image data decoder 1540 may check whether
hierarchical coding pattern information regarding a lower
transformation depth of the current transformation depth has been
encoded, based on the hierarchical coding unit pattern information
regarding the current transformation depth.
[0231] If it is determined that hierarchical coding pattern
information regarding the lower transformation depth is present,
then the hierarchical coding pattern information regarding the
lower transformation depth may be checked. If it is determined
based on the hierarchical coding unit pattern information
corresponding to the current transformation depth that hierarchical
coding pattern information regarding the lower transformation depth
is not present, then the image data decoder 1540 may decode the
transformation unit corresponding to the current transformation
depth, based on coding unit pattern information related to the
transformation unit corresponding to the current transformation
depth.
[0232] Also, if the current transformation depth is a lowermost
depth or a preset final depth, then the transformation unit
corresponding to the current transformation depth may be set to be
decoded regardless of hierarchical coding pattern information
according to transformation depths. If the transformation unit
corresponding to the current transformation depth is decoded, then
the texture information, e.g., a quantization parameter, a
transformation coefficient, a transformation index, etc., may be
decoded.
[0233] The coding unit corresponding to the coded depth may include
at least one transformation unit, and may be decoded by performing
inverse transformation based on transformation unit pattern
information that is set in each of the at least one transformation
unit. That is, whether texture information of a desired
transformation unit has been encoded may be determined based on the
transformation unit pattern information.
[0234] Thus, if it is determined based on the coding unit pattern
information corresponding to the coded depth that the coding unit
has encoded texture information, then the image data decoder 1540
checks transformation unit pattern information of each of
transformation units of the coding unit.
[0235] If it is determined based on the transformation unit pattern
information that the desired transformation unit has encoded
texture information, then the image data decoder 1540 may perform
an inverse transformation on a transformation coefficient of the
desired transformation unit. If it is determined based on the
transformation unit pattern information that the desired
transformation unit does not have encoded texture information, then
the image data decoder 1540 may decode encoded image data of the
desired transformation unit by using information regarding a
transformation unit adjacent to the desired transformation
unit.
[0236] If it is determined based on the coding unit pattern
information corresponding to the coded depth that the desired
transformation unit does not have encoded texture information, then
transformation unit pattern information regarding all
transformation units of the desired coding unit has not been
encoded. In this case, the image data decoder 1540 may not detect
transformation unit pattern information for each of the
transformation units of the desired coding unit.
[0237] In the video encoding apparatus 1400 and the video decoding
apparatus 1500 according to exemplary embodiments, coding unit
pattern information or transformation unit pattern information that
has been encoded based on coding units according to tree structures
and transformation units may be used. Thus, it is possible to
determine whether transformation unit pattern information of each
of the transformation units has been encoded, based on coding unit
pattern information that is set for a coding unit having a
plurality of transformation unit groups. Since the number of coding
units is less than that transformation units, setting coding unit
pattern information for each of the coding units reduces the amount
of data than when setting transformation unit pattern information
for each of all the transformation units, thereby improving bit
transmission efficiency.
[0238] Coding unit pattern information corresponding to a coded
depth that is set according to color components of image data
according to exemplary embodiments will now be described with
reference to FIGS. 18 to 26. It is assumed in the following
exemplary embodiments that one unit of coding unit pattern
information is 1 bit, but it is understood that another exemplary
embodiment is not limited thereto.
[0239] FIGS. 18 to 20 are block diagrams illustrating coding unit
pattern information corresponding to a coded depth when a coding
unit corresponding to a coded depth includes one transformation
unit, according to one or more exemplary embodiments.
[0240] Referring to FIGS. 18 to 20, a first coding unit of color
image data according to the YCbCr color standards includes a luma
component coding unit 1600, a first chroma component coding unit
1610, and a second chroma component coding unit 1620 having a
second chroma component.
[0241] If a transformation unit of the first coding unit is equal
to the first coding unit in size, then the first coding unit
includes only one transformation unit. Thus, the transformation
unit of the first coding unit includes a luma component
transformation unit 1605, a first chroma component transformation
unit 1615, and a second chroma component transformation unit 1625.
Transformation unit pattern information may be set for each of the
luma component transformation unit 1605, the first chroma component
transformation unit 1615, and the second chroma component
transformation unit 1625.
[0242] Referring to FIG. 18, coding unit pattern information
corresponding to a coded depth is not additionally encoded for the
first coding unit. In this case, the coding unit pattern
information output unit 1450 of FIG. 16 does not output coding unit
pattern information corresponding to a coded depth for the first
coding unit. The image data decoder 1540 of FIG. 17 may check only
transformation unit pattern information for each of the luma
component transformation unit 1605, the first chroma component
transformation unit 1615, and the second chroma component
transformation unit 1625 and perform an inverse transformation on
transformation coefficients of the luma component transformation
unit 1605, the first chroma component transformation unit 1615, and
the second chroma component transformation unit 1625, based on the
checking result, without checking coding unit pattern information
corresponding to a coded depth for the first coding unit.
[0243] Referring to FIG. 19, 1-bit coding unit pattern information
corresponding to a coded depth is set for a group 1630 to which a
luma component transformation unit 1600, a first chroma component
transformation unit 1610, and a second chroma component
transformation unit 1620 of a first coding unit belong. In this
case, the coding unit pattern information output unit 1450 of FIG.
16 outputs the 1-bit coding unit pattern information corresponding
to a coded depth for the first coding unit.
[0244] Referring to FIG. 20, 1-bit coding unit pattern information
corresponding to a coded depth is set for each of a group 1640 to
which a luma component coding unit 1600 of a first coding unit
belongs, and a group 1650 to which a first chroma component coding
unit 1610 and a second chroma component coding unit 1620 of the
first coding unit belong. In this case, the coding unit pattern
information output unit 1450 of FIG. 16 outputs a 2-bit coding unit
pattern information corresponding to a coded depth for the first
coding unit.
[0245] According to an exemplary embodiment, the image data decoder
1540 of FIG. 17 may determine whether a desired coding unit
includes encoded texture information by checking either the 1-bit
coding unit pattern information corresponding to a coded depth of
FIG. 19 or the 2-bit coding unit pattern information corresponding
to a coded depth of FIG. 20, for a first coding unit. If the
desired coding unit includes encoded texture information, then the
image data decoder 1540 of FIG. 17 may check transformation unit
pattern information of a corresponding transformation unit and
perform inverse transformation on corresponding transformation
coefficients, based on the checking result.
[0246] FIGS. 21 to 23 illustrate coding unit pattern information
corresponding to a coded depth when a coding unit corresponding to
the coded depth includes four transformation units, according to
exemplary embodiments. Referring to FIGS. 21 to 23, a second coding
unit of color image data according to the YCbCr color standards
includes a luma component coding unit 1700, a first chroma
component coding unit 1710, and a second chroma component coding
unit 1720.
[0247] If the second coding unit includes four transformation
units, then each of the coding units of the second coding unit,
which are categorized according to a color component, also includes
four transformation units. That is, the luma component coding unit
1700 includes four luma component transformation units 1702, 1704,
1706, and 1708, the first chroma component coding unit 1710
includes four first chroma component transformation units 1712,
1714, 1716, and 1718, and the second chroma component coding unit
1720 includes four second chroma component transformation units
1722, 1724, 1726, and 1728.
[0248] Referring to FIG. 21, 1-bit coding unit pattern information
corresponding to a coded depth is set for a group 1730 to which
only the luma component coding unit 1700 of the second coding unit
belongs. However, coding unit pattern information corresponding to
a coding depth is not set for the first chroma component coding
unit 1710 and the second chroma component coding unit 1720.
[0249] In this case, the coding unit pattern information output
unit 1450 of FIG. 16 outputs 1-bit coding unit pattern information
corresponding to the coded depth regarding the luma component
coding unit 1700. Accordingly, the image data decoder 1540 of FIG.
17 checks the 1-bit coding unit pattern information corresponding
to the coded depth regarding the luma component coding unit 1700
and determines whether encoded texture information is present in
the luma component coding unit 1700. If it is determined that the
encoded texture information is present, then the image data decoder
1540 may check transformation unit pattern information of the luma
component transformation units 1702, 1704, 1706, and 1708, and
perform inverse transformation on transformation coefficients of
the transformation units 1702, 1704, 1706, and 1708 based on the
checking result.
[0250] Alternatively, the image data decoder 1540 may check only
transformation unit pattern information of the first chroma
component transformation units 1712, 1714, 1716, and 1718 and the
second chroma component transformation units 1722, 1724, 1726, and
1728 and may perform an inverse transformation on transformation
coefficients of the transformation units 1712, 1714, 1716, 1718,
1722, 1724, 1726, and 1728 based on the checking result, without
checking coding unit pattern information corresponding to a coded
depth of the first chroma component 1710 and the second chroma
component 1720 of the second coding unit.
[0251] Referring to FIG. 22, 1-bit coding unit pattern information
corresponding to a coded depth is set for a group 1740 to which a
luma component coding unit 1700, a first chroma component coding
unit 1710, and a second chroma component coding unit 1720 of a
second coding unit belong. In this case, the coding unit pattern
information output unit 1450 of FIG. 16 outputs the 1-bit coding
unit pattern information corresponding to a coded depth for the
second coding unit.
[0252] Referring to FIG. 23, 1-bit coding unit pattern information
corresponding to a coded depth is set for each of a group 1750 to
which a luma component coding unit 1700 of a second coding unit
belongs, a group 1760 to which a first chroma component coding unit
1710 of the second coding unit belongs, and a group 1770 to which a
second chroma component coding unit 1720 of the second coding unit
belongs. In this case, the coding unit pattern information output
unit 1450 of FIG. 16 outputs a 3-bit coding unit pattern
information corresponding to a coded depth for the second coding
unit.
[0253] The image data decoder 1540 of FIG. 17 may determine whether
encoded texture information is present in a coding unit by checking
either 1-bit coding unit pattern information corresponding to the
coded depth (see FIG. 22) or 3-bit coding unit pattern information
corresponding to the coded depth (see FIG. 23), for the second
coding unit. If it is determined that the encoded texture
information is present, then the image data decoder 1540 may check
transformation unit pattern information of transformation units
corresponding to the coding unit and perform an inverse
transformation on transformation coefficients of the transformation
units based on the checking result.
[0254] FIGS. 24 to 26 illustrate coding unit pattern information
corresponding to a coded depth when a coding unit corresponding to
the coded depth includes a plurality of transformation units,
according to exemplary embodiments. Referring to FIGS. 24 to 26,
third coding unit of color image data according to the YCbCr
standards includes a luma component coding unit 1800, a first
chroma component coding unit 1820, and a second chroma component
coding unit 1830.
[0255] If the third coding unit includes at least four
transformation units, then the luma component coding unit 1800 of
the third coding unit also includes at least four transformation
units. That is, the number of transformation units of the luma
component coding unit 1800 is equal to the number of transformation
units of the third coding unit. For example, if the third coding
unit includes sixteen transformation units, then the luma component
coding unit 1800 also includes sixteen luma component
transformation units 1801, 1802, 1803, 1804, 1805, 1806, 1807,
1808, 1809, 1810, 1811, 1812, 1813, 1814, 1815, and 1816.
[0256] Each of the first chroma component coding unit 1820 and the
second chroma component coding unit 1830 may include four
transformation units. That is, the first chroma component coding
unit 1810 may include four first chroma component transformation
units 1822, 1824, 1826, and 1828, and the second chroma component
coding units 1830 may include four second chroma component
transformation units 1832, 1834, 1836, and 1838.
[0257] One unit of coding unit pattern information corresponding to
a coded depth may be set as coding unit pattern information
corresponding to a coded depth for a part of the luma component
coding unit 1800, for a group to which a predetermined number of
luma component transformation units belong. For example, coding
unit pattern information corresponding to a coded depth may be set
for each of groups to which four luma component transformation
units of the luma component coding unit 1800 belong. That is, in
the luma component coding unit 1800, 1-bit coding unit pattern
information may be set for each of a group 1840 to which four
transformation units 1801, 1802, 1803, and 1804 belong, a group
1850 to which four transformation units 1805, 1806, 1807, and 1808
belong, a group 1860 to which four transformation units 1809, 1810,
1811, and 1812 belong, and a group 1870 to which four
transformation units 1813, 1814, 1815, and 1816 belong.
[0258] Referring to FIG. 24, coding unit pattern information
corresponding to a coded depth is not set for the first chroma
component coding unit 1820 and the second chroma component coding
unit 1830.
[0259] In this case, the coding unit pattern information output
unit 1450 of FIG. 16 outputs 4-bit coding pattern information
corresponding to the coded depth for the groups 1840, 1850, 1860,
and 1870 of the luma component coding unit 1800. The image data
decoder 1540 of FIG. 17 checks the 4-bit coding pattern information
corresponding to the coded depth, and determines whether encoded
texture information is present for each of the groups 1840, 1850,
1860, and 1870.
[0260] Alternatively, the image data decoder 1540 may check
transformation unit pattern information of the first chroma
component transformation units 1822, 1824, 1826, and 1828 and the
second chroma component transformation units 1832, 1834, 1836, and
1838 without checking pattern information corresponding to the
coded depth for the first chroma component 1820 and the second
chroma component coding unit 1830.
[0261] Referring to FIG. 25, in a third coding unit, 1-bit coding
unit pattern information corresponding to a coded depth is set for
each of a plurality of luma component coding unit groups 1840,
1850, 1860, and 1870, a group 1880 to which a first chroma
component coding unit 1820 belongs, and a group 1885 to which a
second chroma component coding unit 1830 belongs. In this case, the
coding unit pattern information output unit 1450 of FIG. 16 outputs
6-bit coding unit pattern information corresponding to the coded
depth, for the third coding unit.
[0262] Referring to FIG. 26, in a third coding unit, 1-bit coding
unit pattern information corresponding to a coded depth is set for
each of a plurality of luma component coding unit groups 1840,
1850, 1860, and 1870, and a group 1890 to which a first chroma
component coding unit 1820 and a second chroma component coding
unit 1830 belong. In this case, the coding unit pattern information
output unit 1450 of FIG. 16 outputs 5-bit coding unit pattern
information corresponding to the coded depth, for the third coding
unit.
[0263] The image data decoder 1540 of FIG. 17 determines whether
encoded texture information is present for the coding unit by
checking either the 6-bit coding unit pattern information
corresponding to the coded depth (see FIG. 25) or the 5-bit coding
unit pattern information corresponding to the coded depth (see FIG.
26) for the third coding unit. If it is determined that the encoded
texture information is present, the image data decoder 1540 may
check transformation unit pattern information of a transformation
unit included in the coding unit, and perform an inverse
transformation on transformation coefficients of the transformation
units based on the checking result.
[0264] As described above, according to one or more exemplary
embodiments, coding unit pattern information may be set for each of
color components, and a plurality of pieces of coding unit pattern
information of the same coding unit, which are categorized
according to a color component, may be combined and encoded.
[0265] In a video encoding apparatus 100 and a video decoding
apparatus 200 according to exemplary embodiments, a plurality of
pieces of coding unit pattern information that are categorized
according to a color component may be encoded or decoded in an
integrated manner, based on the relationship among coding unit
pattern information regarding a luma component, first chroma
component, and second chroma component of the same coding unit and
the relationship among coding unit pattern information of the same
color component regarding neighboring coding units.
[0266] For example, for variable-length coding (VLC) of a current
coding unit, coding unit pattern information regarding a luma
component, coding unit pattern information regarding a first chroma
component, and coding unit pattern information regarding a second
chroma component may be combined and encoded using one
codeword.
[0267] Furthermore, by way of example, a VLC table may be set in
such as manner that different unary codewords correspond to
combinations of a plurality of pieces of coding unit pattern
information, which are categorized according to a color component,
respectively. Accordingly, the plurality of pieces of coding unit
pattern information may be encoded in an integrated manner. A VLC
table may be selected in such a manner that the shorter a unary
codeword, the higher probabilities of the combinations of the
plurality of pieces of coding unit pattern information.
[0268] As described above, it is possible to improve encoding
efficiency by encoding or decoding a plurality of pieces of coding
unit pattern information, which are categorized according to a
color component, in an integrated manner, based on the relationship
among a plurality of pieces of coding unit pattern information of
the same coding unit that are categorized according to a color
component and the relationship among a plurality of pieces of
coding unit pattern information of the same color component of
neighboring coding units.
[0269] According to an exemplary embodiment, coding unit pattern
information corresponding to a coded depth is set in a coding unit
corresponding to the coded depth, hierarchical coding unit pattern
information is set in transformation units according to
transformation depths, which are divided from the coding unit
corresponding to the coded depth, and transformation unit pattern
information is set in a final transformation unit.
[0270] Thus, the coding unit pattern information corresponding to
the coded depth, the hierarchical coding unit pattern information,
and the transformation unit pattern information may be defined
continuously, based on the hierarchical structures of a coding unit
and a transformation unit according to an exemplary embodiment.
[0271] Accordingly, in the video encoding apparatus 100 and the
video decoding apparatus 200 according to exemplary embodiments, it
is possible to determine whether a texture component that is not 0
and that is included from a coding unit to a transformation unit
has been encoded by using one piece of data unit pattern
information that is hierarchically set according to a
transformation depth, without differentiating the coding unit
pattern information corresponding to the coded depth, the
hierarchical coding unit pattern information, and the
transformation unit pattern information from one another.
[0272] FIG. 27 is a diagram illustrating hierarchical coding unit
pattern information according to an exemplary embodiment. Referring
to FIG. 27, transformation units 1912, 1914, 1916, 1918, 1920,
1930, 1942, 1944, 1946, 1948, 1954, 1956, and 1958, the sizes of
which are determined according to corresponding transformation
depths, respectively, are set for a maximum coding unit 1900.
[0273] For example, a transformation unit corresponding to the
transformation depth of 0 is equal to the maximum coding unit 1900
in size, though the maximum coding unit 1900 illustrated in FIG. 27
does not include the transformation unit corresponding to the
transformation depth of 0.
[0274] The transformation units 1920 and 1930 are equal to the
result of splitting the height and width of the transformation unit
corresponding to the transformation depth of 0 into two equal
parts, and correspond to a transformation depth of 1. Similarly,
the transformation units 1912, 1914, 1916, 1918, 1954, 1956, and
1958 correspond to a transformation depth of 2, and transformation
units 1942, 1944, 1946, and 1948 correspond to a transformation
depth of 3.
[0275] The hierarchical coding unit pattern information indicates
whether hierarchical coding unit pattern information regarding a
lower transformation depth is to be encoded. Furthermore, the
hierarchical coding unit pattern information may reveal whether
texture information of the lower transformation depth has been
encoded.
[0276] The maximum coding unit 1900 does not include the
transformation unit corresponding to the transformation depth of 0,
and uses texture information of a transformation unit corresponding
to the transformation depth of 1 which is lower than the
transformation depth of 0. Thus, 1-bit hierarchical coding unit
pattern information 1960 is set for the transformation depth of
0.
[0277] Regarding the transformation depth of 1, the transformation
unit 1920 and the 1930 are decoded in the transformation depth of
1, and thus, texture information of a transformation unit
corresponding to the transformation of depth 2 which is lower than
the transformation depth of 1 may not be encoded. Also,
hierarchical coding unit pattern information regarding the
transformation depth of 2 may not be set. Thus, 1-bit hierarchical
coding unit pattern information regarding the transformation depth
of 1, which indicates that texture information of hierarchical
coding unit pattern information regarding the transformation depth
of 2 may not be encoded, is provided for each of the transformation
units 1920 and 1930.
[0278] However, texture information of a transformation unit
corresponding to the transformation depth of 2 which is lower than
the transformation depth of 1 is to be encoded for each of a group,
corresponding to the transformation depth of 1, to which the
transformation units 1912, 1914, 1916, and 1918 corresponding to
the transformation depth of 2 belong, and a group, corresponding to
the transformation depth of 1, to which the transformation units
1942, 1944, 1946, 1948, 1954, and 1956, and 1958 belong. Thus,
coding unit pattern information regarding the transformation depth
of 2 may be encoded, and 1-bit hierarchical coding unit pattern
information regarding the transformation depth of 1 may be set for
each of the groups so as to indicate this fact.
[0279] Accordingly, a total of 4-bit hierarchical coding unit
pattern information 1970 is set for the transformation depth of
1.
[0280] Regarding the transformation depth of 2, the transformation
units 1912, 1914, 1916, 1918, 1954, 1956, and 1958 may be decoded
in the transformation depth of 2. For this reason, texture
information of a transformation unit corresponding to the
transformation depth of 3 which is lower than the transformation
depth of 2 may not be encoded, and thus, hierarchical coding unit
pattern information regarding the transformation depth of 3 may not
be set. Thus, 1-bit hierarchical coding unit pattern information
regarding the transformation depth of 2 may be set for each of the
transformation units 1912, 1914, 1916, 1918, 1954, 1956, and 1958
so as to indicate that hierarchical coding unit pattern information
regarding the transformation depth of 3 may not be encoded.
[0281] However, information of a transformation unit corresponding
to the transformation depth of 3 may be encoded for a group,
corresponding to the transformation depth of 2, to which the
transformation units 1942, 1944, 1946, and 1948 belong. Thus, the
coding unit pattern information regarding the transformation depth
of 3 may be encoded, and 1-bit hierarchical coding unit pattern
information regarding the transformation depth of 2 may be set so
as to indicate this fact.
[0282] Accordingly, a total of 8-bit hierarchical coding unit
pattern information 1980 may be set for the transformation depth of
2.
[0283] The transformation depth of 3 is a final transformation
depth, and therefore, 1-bit hierarchical coding unit pattern
information regarding the transformation depth of 3 may be set for
each of the transformation units 1942, 1944, 1946, and 1948 so as
to indicate that hierarchical coding unit pattern information
regarding a lower transformation depth may not be encoded. Thus, a
total of 4-bit hierarchical coding unit pattern information 1990
may be set for the transformation depth of 3,
[0284] FIG. 28 is a flowchart illustrating a method of encoding
video data by using coding unit pattern information, according to
an exemplary embodiment. Referring to FIG. 28, in operation 2010, a
current picture is split into at least one maximum coding unit. In
operation 2020, a coded depth to output a final encoding result
according to at least one split region, which is obtained by
splitting a region of each of the at least one maximum coding unit
according to depths, is determined by encoding the at least one
split region, and a coding unit according to a tree structure is
determined.
[0285] In operation 2030, a result of encoding image data according
to one coded depth for each of the at least one maximum coding
unit, and a result of encoding information regarding the coded
depth and an encoding mode are output.
[0286] Coding unit pattern information corresponding to a coded
depth, which indicates whether texture information of coding units
according to coded depths of the at least one maximum coding unit
has been encoded, may be encoded as coding unit pattern information
of the at least one maximum coding unit. If hierarchical coding
unit pattern information is hierarchically encoded according to a
transformation depth, then each of a plurality of pieces of
hierarchical coding unit pattern information corresponding to
transformation depths indicates whether the hierarchical coding
unit pattern information regarding a transformation depth that is
lower than the corresponding transformation depth has been
encoded.
[0287] FIG. 29 is a flowchart illustrating a method of decoding
video data by using coding unit pattern information, according to
an exemplary embodiment. Referring to FIG. 29, in operation 2110, a
bitstream of encoded video is received and parsed.
[0288] In operation 2120, image data of a current picture assigned
to at least one maximum coding unit, information regarding a coded
depth of a coding unit according to a tree structure for each of
the at least one maximum coding unit, and information regarding an
encoding mode, are extracted from the parsed bitstream. Also, the
coding unit pattern information indicating whether texture
information of a maximum coding unit has been encoded is extracted
on a basis of the at least one maximum coding unit. Coding unit
pattern information corresponding to a coded depth regarding coding
units according to coded depths of each maximum coding unit, and
hierarchical coding unit pattern information may be extracted as
coding unit pattern information of the at least one maximum coding
unit.
[0289] In operation 2130, encoded image data corresponding to the
at least one maximum coding unit is decoded, based on the coded
depths of the at least one maximum coding unit, information
regarding an encoding mode, and information regarding the coding
unit pattern information, thereby reconstructing the image data. It
is possible to determine whether texture information of the coding
unit corresponding to the coded depth has been encoded based on the
coding unit pattern information corresponding to the coded depth.
Also, it is possible to determine whether the hierarchical coding
unit pattern information regarding a lower transformation depth has
been encoded based on the hierarchical coding unit pattern
information regarding each of the transformation depths.
[0290] In the coding unit corresponding to the coded depth, data
encoded in a transformation unit may be decoded by performing an
inverse transformation on a transformation coefficient based on
transformation unit pattern information of the transformation
unit.
[0291] In general, in a related art video encoding/decoding method,
a 16.times.16 or 8.times.8 macroblock is used as a transformation
unit when transformation or inverse transformation is performed on
image data. Coded block pattern information is encoded and
transmitted on a macro block basis during an encoding process, and
is used for a decoding process.
[0292] In contrast, according to the above-described exemplary
embodiments, coding unit pattern information based on a
hierarchically structured coding unit and transformation unit is
used. Thus, the coding unit pattern information may be encoded in a
coding unit which is greater than a macroblock or is a variously
sized data unit. Also, the coding unit pattern information may be
encoded in a coding unit, which includes a plurality of
hierarchical structured transformation units according to a tree
structure, in an integrated manner. Accordingly, the efficiency of
encoding/decoding and transmitting the coding unit pattern
information can be improved.
[0293] One or more exemplary embodiments may be embodied as a
computer program. The computer program may be stored in a computer
readable recording medium, and executed using a general digital
computer. Examples of the computer readable medium include a
magnetic recording medium (a ROM, a floppy disc, a hard disc,
etc.), and an optical recording medium (a CD-ROM, a DVD, etc.).
[0294] While exemplary embodiments have been particularly shown and
described, it will be understood by those of ordinary skill in the
art that various changes in form and details may be made therein
without departing from the spirit and scope of the present
inventive concept as defined by the appended claims. The exemplary
embodiments should be considered in descriptive sense only and not
for purposes of limitation. Therefore, the scope of the present
inventive concept is defined not by the detailed description of
exemplary embodiments, but by the appended claims, and all
differences within the scope will be construed as being included in
the present inventive concept.
* * * * *