Video Quality Evaluation Methodologyand Verification Testing of HEVC

Compression Performance

Under the guidance of:

Mr. Justin GopinathAssociate professor , Dept of CSE,CIT, Gubbi, Tumakuru.

Presentation by:

Rajath K1CG12CS074

Overview of Presentation • Introduction

• Performance measurements • HEVC verification methods

• HEVC verification test results • Conclusions

These video coding standards are the joint work of the same two bodies

• ISO/IEC Moving Picture Experts Group (MPEG)

• ITU-T Video Coding Experts Group (VCEG),through the JCT-VC.

Major Video Coding Standards

Mid 2010s: HEVC

Mid 1990s: MPEG-2

Mid 2000s: H.264/AVC

INTRODUCTION

HEVC version 1 was completed in January 2013 • published by ISO/IEC as MPEG-H Part 2

• published by ITU-T as H.265

For formal evaluation of HEVC performance, the JCT-VC performed a subjective evaluation of resolution varying from 480p up to UHD with frame rates up to 60 Hz.

Performance Measurements Two different types of measurement of compression performance

Objective evaluation

PSNR (Peak signal to noise ratio)

• PSNR is defined as the ratio between the maximum possible power of the signal and the power of noise.

• PSNR computed as:

• For the HEVC verification test a degradation category rating (DCR) test method was selected.

• It was used to evaluate the quality with a quality rating scale.

• The numerical scale helps to avoid misinterpretations.

Subjective evaluation

• Mean Opinion Score (MOS) from human test subjects

• Requires a large number of test subjects to give good confidence intervals

• Expensive and time-consuming formal subjective tests

JCT-VC Verification Testing of HEVC

Verification testing compared HEVC and AVC standards

• Test sequences were compressed using two encoding

• HEVC Main profile• AVC High profile

• The HEVC verification tests were carried out for fourcategories of resolutions:

• UHD• 1080p• 720p • 480p

Example of UHD-1 Sequence

-UHD test sequence.

-Subjective and objective evaluation results for UHD content;subjective results, with associated 95% confidence intervals

Verification Test Results

•Subjective test results require careful analysis

• Mean Opinion Score (MOS) calculated for each test point

• In this HEVC verification test, a correlation index greater than or equal to 0.75 is considered as valid for the acceptance of the viewer’s scorings; otherwise, the viewer

is considered as an unreliable.

• Revised MOS were then plotted with 95% confidence intervals

• Each HEVC test point categorized by compared to AVC points

• Bit rate required for HEVC was

(a) Less than half that of AVC

(b) About half that of AVC

(c) More than half that of AVC

Example of test point categories

Estimated efficiency improvement

Average bit rate savings

Conclusions

• HEVC required no more than half bit rate of AVC in 86% of cases

• Implies that HEVC target of doubling the compression efficiency has been met or exceeded

• Bjøntegaard Delta calculations indicate greater bit rate savings at the higher resolutions

•52% for 480p •56% for 720p •62% for 1080p •64% for UHD-1 (2160p)

• This confirms that the subjective quality improvements of HEVC are typically greater than the objective.

THANK YOU