Graphics Reference
In-Depth Information
rqt_root_cbf=1
cbf_cb=1,
cbf_cr=1
RQT
depth = 0
split_transform_flag=0 split_transform_flag=0
split_transform_flag=1 split_transform_flag=0
cbf_cb=1,
cbf_cr=0
cbf_cb,
cbf_cr,
cbf_luma
cbf_cb,
cbf_cr,
cbf_luma
cbf_cb,
cbf_cr,
cbf_luma
RQT
depth = 1
split_transform_flag=1 split_transform_flag=0
split_transform_flag=0
cbf_cb
cbf_luma
cbf_cb
cbf_luma
cbf_cb
cbf_luma
RQT
depth = 2
cbf_cb=1
split_transform_flag=1
split_transform_flag=0
for each
TB
split_transform_flag=0
cbf_cb
RQT
depth = 3
cbf_cb
cbf_luma
cbf_cb
cbf_luma
cbf_cb
cbf_luma
RQT
depth = 4
cbf_luma
cbf_luma
cbf_luma
cbf_luma
Fig. 8.11 Illustration of signaling of split_transform_flag , cbf_luma , cbf_cb ,and
cbf_cr for an RQT with depth 4. Note that at RQT depth = 0, no split_transform_flag
is signaled since an implicit transform split occurs for CU of 64 as n max
32. cbf_luma is only
signaled for leaf transform blocks (highlighted in red ). cbf_cb and cbf_cr are signaled for the
root node and all nodes where the corresponding CBF at the parent node is non-zero, except for
the nodes related to TrafoSize
D
D
4
cbf_cb and cbf_cr , four contexts are used such that the corresponding context
increment depends on the RQT depth (with admissible values between 0 and 3, since
for the case of TrafoSize D 4 no chroma CBFs are transmitted), whereas for cbf
_luma only two contexts are provided with its discriminating context increment
depending on the condition RQT depth D 0. For more background on the use of
RQT and related syntax elements, please refer to Chap. 3 .
8.6.4
Significance Map
In H.264/AVC, the significance map for each transform block is signaled by
transmitting a significant_coeff_flag (SIG) for each position to indicate
whether the coefficient is non-zero. The positions are processed in an order based
on a zig-zag scan. After each non-zero SIG, an additional flag called last
_significant_coeff_flag (LAST) is immediately sent to indicate whether
 
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