A fast CU size decision algorithm for HEVC

Jaeho Lee, Seongwan Kim, Kyungmin Lim, Sangyoun Lee

Research output: Contribution to journalArticlepeer-review

82 Citations (Scopus)


High Efficiency Video Coding (HEVC) employs a coding unit (CU), prediction unit (PU), and transform unit (TU) based on the quadtree coding tree unit (CTU) structure to improve coding efficiency. However, the computational complexity increases greatly because the rate-distortion (RD) optimization process should be performed for all CUs, PUs, and TUs to obtain the optimal CTU partition. In this paper, a fast CU size decision algorithm is proposed to reduce the encoder complexity of HEVC. Based on the statistical analysis, three approaches with SKIP mode decision (SMD), CU skip estimation (CUSE), and early CU termination (ECUT) are considered. In SMD, it is determined that the remaining modes except for SKIP mode are preformed or not. CUSE and ECUT determine that larger CU sizes and smaller CU sizes are coded or not, respectively. Thresholds for SMD, CUSE, and ECUT are designed based on Bayes' rule with a complexity factor. Update process is performed to estimate the statistical parameters for SMD, CUSE, and ECUT considering the characteristic of RD cost. The experimental results demonstrate that the proposed CU size decision algorithm significantly reduces computational complexity by 69% on average with 2.99% Bjontegaard difference bitrate (BDBR) increase for random access. The complexity reduction and BDBR increase for low delay are 68% and 2.46%, respectively. The experimental results also show that our proposed scheme performs well for various characteristic of sequences and outperforms the two previous state-of-the-art works.

Original languageEnglish
Article number6857334
Pages (from-to)411-421
Number of pages11
JournalIEEE Transactions on Circuits and Systems for Video Technology
Issue number3
Publication statusPublished - 2015 Mar 1

Bibliographical note

Publisher Copyright:
© 1991-2012 IEEE.

All Science Journal Classification (ASJC) codes

  • Media Technology
  • Electrical and Electronic Engineering


Dive into the research topics of 'A fast CU size decision algorithm for HEVC'. Together they form a unique fingerprint.

Cite this