Full Parallax 3D Video Content Compression - Novel 3D Media Technologies - page 64

number of views. The proposed structure Central2D provides final BD-rate gains
up to 8.2% and 29.1% against the basic anchor, in the 3 3 and 11 5 views

configuration, respectively.

4.3.3 Adaptation and Improvements of Inter-view
Coding Tools

4.3.3.1 Merge Candidate List Improvement

A normative modification of NBDV and IVMP is also proposed in [ 52 ]. NBDV and
IVMP coding tools are specifically implemented to work in the Common Test
Conditions [ 53 ], with only one horizontal inter-view reference picture, which is the
central baseview (with view index 0). First an adaptation is done that enables the
use of several inter-view reference pictures, possibly horizontal or vertical, and
with a view index different from 0 (not central).
In addition to this adaptation, we further improve NBDV. The modified NBDV
searches for two DVs (one for each inter-view reference picture) when encoding a B
view that uses one horizontal and one vertical inter-view reference pictures. This
search for a second DV does not provide BD-rate gain in itself but is meant to be
used for IPMC and DMV as follows. The new second DV allows to insert a second
IPMC at the second place of the merge candidate list. Inter-view bi-prediction in
both directions at the same time is enabled for the DMV merge candidate by using
the couple of DVs.

4.3.3.2 Inter-view Derivation of the Second DV

In order to improve the efficiency of modified IPMC and DMV candidates, we
propose to increase the likelihood of finding a second DV with NBDV. Figure 4.17
shows the steps of this method. For the current coding view, NBDV first finds a
horizontal DV pointing to a reference CU in an inter-view reference picture. If this
horizontal reference picture uses itself a vertical inter-view reference picture, and if
the reference CU is coded by inter-view prediction, then the vertical DV used for
the prediction is derived (i.e., copied) as a second DV for the current coding CU,
and then used by IPMC and DMV as described in the previous section. This method
can be applied to B views with one horizontal and one vertical references, which
makes the Central2D structure the most adequate for these coding tools.

4.3.3.3 Experimental Results

The proposed adaptation and improvements of NBDV and IVMP coding tools are
tested in this section. Experiments are performed under 3D-HEVC reference