Game Development Reference
In-Depth Information
Fig. 7.9
Syntax parsing flow of SAO
in the bit-stream to reduce the latency (Chen et al.
2013b
). In each LCU, the syntax
element parsing flow diagram is in Fig.
7.9
.
For each LCU, there are three options for SAO parameters, reusing SAO para-
meters of the left LCU, reusing SAO parameters of the up LCU, or transmitting
new SAP parameter. The SAO merging information (named SAO_merge_mode) is
shared by three color components. Thus if the current LCU selects SAO merge-left
or SAO merge-up, all SAO parameters of the left or up LCU are copied for reuse,
and no more information is sent.
The SAO parameters of one LCU are the EO, BO, or OFF indications for three
color components respectively. If BO is selected, four offset and two positions are
signaled, and if EO is selected, four offsets followed by the classification patterns
are signaled. Which mode is used in one LCU is determined by the rate-distortion
performance. These flexible mode designs make the SAO efficiently improve the
compression performance by reducing distortions with few bits transmitted.
7.4 Adaptive Loop Filter
The adaptive loop filter introduces the Wiener filter in the coding loop and also aims
to reduce coding error of both output pictures and reference pictures for nonboundary
pixels as well as boundary ones. It can not only improve the quality of the current
