![](https://csdnimg.cn/release/download_crawler_static/30326107/bg13.jpg)
structure. However, for I slices, the luma and chroma can have separate block tree structures. When
separate block tree mode is applied, luma CTB is partitioned into CUs by one coding tree structure, and
the chroma CTBs are partitioned into chroma CUs by another coding tree structure. This means that a CU
in an I slice may consist of
a
coding block of the luma component or coding blocks of two chroma
components, and a CU in a
P
or B slice always consists of
coding blocks of
all three colour components
unless the video is monochrome.
3.2.4 CU splits on picture boundaries
Similar to HEVC, when a portion of
a tree node block exceeds the bottom or right picture boundary, the
tree node block is forced to be split until the all samples of
every coded CU are located inside the picture
boundaries. The following splitting rules are applied in the VVC:
-
If
any portion of
a
tree node block exceeds the bottom or the right picture boundaries, TT splitting
is
not allowed.
-
If
any
portion of
a
tree node block exceeds the bottom or the right picture boundaries, and any of
QT
and BT splitting is not allowed due to block size restriction, the block is forced to be split with
QT
split
mode.
-
Otherwise if
a
portion of
a
tree node block exceeds both the bottom and the right
picture boundaries,
-
If
the block is a QT node and the size of
the block is larger than the minimum QT size, the block
is forced
to be split
with QT split mode.
-
Otherwise, the block is forced to be split with SPLITBTHOR
mode
-
Otherwise if
a
portion of
a
tree node block exceeds the bottom picture boundaries,
-
If
the block is a QT node, and the size of
the block is larger than the minimum
QT
size, and the
size of the block is larger than the maximum BT size, the block is forced to be split with
QT
split mode.
-
Otherwise, if
the block is a QT node, and the size of
the block is larger than the minimum
QT
size
and the size of
the block is smaller than or equal to the maximum BT size, the block is forced to
be split with QT split mode or SPLIT BT HOR mode and a flag split
qt
Jlag
is signalled to
specify the partitioning mode for this case.
-
Otherwise (the block is a BTT node or the size of the block is smaller than or equal to the
minimum
QT
size), the block is forced to be split
with SPLIT BT HOR mode.
-
Otherwise if
a
portion of
a
tree node block exceeds the right
picture boundaries,
-
If
the block is a QT node, and the size of
the block is larger than the minimum
QT
size, and the
size of the block is larger than the maximum BT size, the block is forced to be split with
QT
split mode.
-
Otherwise, if
the block is a QT node, and the size of
the block is larger than the minimum
QT
size
and the size of
the block is smaller than or equal to the maximum BT size, the block is forced to
be split with QT split mode or SPLITBTVER
mode and
a
flag split
qt
Jlag
is signalled to
specify the partitioning mode for this case.
-
Otherwise (the block is a BTT node or the size of the block is smaller than or equal to the
minimum
QT
size), the block is forced to be split
with SPLIT BT VER
mode.
3.2.5 Restrictions on redundant CU splits
The quadtree with nested multi-type tree coding block structure provides
a
highly flexible block
partitioning structure. Due to the types of splits supported the multi-type tree, different splitting patterns
could potentially result in the same coding block structure. In VVC, some of these redundant splitting
patterns are disallowed.
Date Saved: 2021-10-09
Page: 19