Game Development Reference
In-Depth Information
Fig. 3.9
Architecture of AVS2 smart scene video coding
et al.
2013
), which is illustrated in Fig.
3.9
. G-pictures and S-pictures are defined to
further exploit the temporal redundancy and facilitate video event generation such
as object segmentation and motion detection. The G-picture is a special I-picture,
which is stored in a separate backgroundmemory. The S-picture is a special P-picture,
which can be only predicted from a reconstructed G-picture or a virtual G picture
which does not exist in the actual input sequence but is modeled from input pictures
and encoded into the stream to act as a reference picture.
The G-picture is initialized by background initialization and updated by back-
ground modeling with methods such as median filtering, fast implementation of
Gaussian Mixture model, etc. In this way, the selected or generated G-picture can
well represent the background of a scene with rare occluding foreground objects
and noise. Once a G-picture is obtained, it is encoded and the reconstructed pic-
ture is stored into the background memory in the encoder/decoder and updated only
if a new G-picture is selected or generated. After that, S-pictures can be involved
in the encoding process by S-picture decision. Except that it uses a G-picture as
a reference, the S-picture owns similar utilities as the traditional I-picture such as
error resilience and random access. Therefore, the pictures which should be coded
as traditional I-pictures can be candidate S-pictures, such as the first picture of one
GOP, or scene change, etc. Besides bringing about more prediction opportunity for
those background blocks which normally dominates a picture, an additional benefit
from the background picture is a new prediction mode called background difference
