Game Development Reference
In-Depth Information
pictures. QP offset is used to set the QP of current coding picture. And the number of
reference pictures and the delta COI between current picture and reference picture
are used to set up reference picture set for current picture. Meanwhile, the number of
pictures that need to remove from buffer and delta COI between pictures from buffer
and current picture are used to manage DPB.
At the encoder side, the syntax element coi is used to transmit the COI of current
picture, which is defined as follows:
coi
=
COI%256
(9.8)
By marking and transmitting the COI information, the decoder side could figure out
the actual coding order of current picture even there are some pictures lost during
transmission. Meanwhile, the
delta
_
poi
is defined to derive the POI in decoder side,
which is defined as the equation below.
delta
_
poi
=
COI
−
POI
(9.9)
The syntax element
delta
_
poi
is used to denote the only display order of current
picture. And the decoder side derives the POI of current coding picture by subtract
delta
_
poi
from COI.
In the reference picture list and removed picture list, the delta COI of reference
pictures is recorded. By deriving the COI and POI of reference pictures, the reference
pictures for current coding picture can be set.
At the encoder side, it is necessary to write the reference manage information
with additional bits. However, it is redundant to transmit RCS for each picture since
the RCS is of great similarity for the same position in the different GOP. The bits for
reference information will account for a high percentage especially for low resolution
video sequences. In our proposed scheme, several RCS sets are used and signaled in
the sequence header to save bit rate instead of writing reference configuration set of
each coding picture in picture header. And only the index of RCS is transmitted in
picture header, signaling the reference scheme that the current coding or decoding
picture takes. Meanwhile, a special RCS set can also be written into picture header if
none of the RCS scheme from the sequence header is taken for the current decoding
picture. And a flag is used to signal whether an index of sequence header is used or
a special RCS is transmitted in picture header.
9.1.2.2 Encoding Process
After the determination of RCS, the next step is to encode the information of RCS and
manage the DPB. In the proposed scheme, the encoder reads reference management
information from the configuration file and then initializes the reference information
of current picture. The COI and POI of current coding picture is configured in encoder
side. The reference list and total number of reference pictures are initializedmanually.
The whole process includes the following four aspects.
