Abstract
Google has recently been developing a next generation opensource
video codec called
VP9, as part of the
experimental branch of the libvpx repository included in the WebM project (http://www.webmproject.org/). Starting
from the VP8 video codec released by Google in 2010 as the baseline, a number of enhancements and new tools have
been added to improve the coding efficiency. This paper provides a technical overview of the current status of this
project along with comparisons and other stateoftheart
video codecs H.
264/AVC and HEVC. The new tools that
have been added so far include: larger prediction block sizes up to 64x64, various forms of compound INTER
prediction, more modes for INTRA prediction, ⅛pel
motion vectors and 8tap
switchable subpel interpolation filters,
improved motion reference generation and motion vector coding, improved entropy coding and framelevel
entropy
adaptation for various symbols, improved loop filtering, incorporation of Asymmetric Discrete Sine Transforms and
larger 16x16 and 32x32 DCTs, frame level segmentation to group similar areas together, etc. Other tools and various
bitstream
features are being actively worked on as well. The VP9 bitstream
is expected to be finalized by earlyto
mid2013.
Results show VP9 to be quite competitive in performance with mainstream stateoftheart
codecs.
