A block level adaptive MV resolution for video coding
The latest video coding standard, HEVC, uses quarter pixel motion vector (MV) resolution for motion compensation. The adaptation of MV resolution supported by PMVR (progressive MV resolution) brings further improvement of the performance, by progressively adjusting the resolution according to the distance between the MV and the MV predictor (MVP). In this work, we propose to improve PMVR by adapting MV resolution at the prediction unit (PU) level relying on its size and its average absolute gradient. We additionally perform a smarter motion estimation around multiple MV predictors to fully take advantage of the proposed scheme. Compared to HEVC reference software (HM-16.6), the proposed method provides 1.2%, 3.2% and 1.2% average BD rate savings respectively for random access (RA), low-delay P (LP) and low-delay (LD) configurations.