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26 2 Hybrid Video Coding
2.2 Technical Evolution
Although the framework of hybrid video coding has changed little in the past few
decades, compression technologies of motion compensation, transform, quantiza-
tion, and entropy coding have been continuously improving. Furthermore, new com-
pression technologies such as intra prediction, deblocking filtering, and sample adap-
tive offset (SAO) filtering are introduced into the framework. Next, we will compare
the compression technologies used in H.261 [8], MPEG-1 [9], MPEG-2 [10], MPEG-
4 [11], H.264 [12, 13], and HEVC [14]. By the comparison, we can clearly see the
trend of the developments on video compression.
2.2.1 H.261
H.261 is the first standard based on the hybrid video coding framework,