كليدواژه :
H.264/AVC , Rate-distortion optimization , split/merge , similar predicted-pixels , intra- and inter-prediction
چكيده فارسي :
Summary: H.264/AVC, the latest video coding standard, adopts rate-distortion optimization (RDO) technique to obtain the
best intra- and inter-prediction, while maximizing visual quality and minimizing the required bitrate. However, the full RD
cost calculation for all intra-prediction modes, the exhaustive searches for finding optimal motion vectors for all block sizes,
and the multiple references frame procedure considerably increase its computational complexity with the allowed number
of prediction modes. In order to reduce the complexity, the authors have previously proposed an approach for both interand
intra-mode decisions that takes into account the several effective parameters, image content type, quantization
parameter, correlation of motion vectors and motion details of video objects. In order to reduce the complexity, here we
propose a new two-step adaptive search range decision by developing a combination of previous algorithm. The first step of
our adaptive search range decision determines the search range for current MB according to the motion vectors of the
previous MBs. In the second step, the motion vector obtained in the current frame is used to adaptively searching the
window size of the previous reference frame for multi-frame motion estimation. As such, only a subset of inter- and intramodes
is chosen for RDO calculation. Experimental results show that the proposed algorithm reduces the total encoding
cost with negligible loss in PSNR and a slightly increase in the required bitrate, when compared to our previous algorithm
and other algorithms reported in the literature.
