Hot news:

If you find a spelling error, please select an incorrect text and press Ctrl+Enter. Thank you!

[an error occurred while processing this directive] Compression project >> Video Area Home [an error occurred while processing this directive]
RUSSIAN VERSION

MSU Subjective Comparison of Modern Video Codecs

MSU Graphics & Media Lab (Video Group)

Project head: Dr. Dmitriy Vatolin
Organization of assessment: Alexander Parshin, Petrov Oleg
Refinement, translation: Oleg Petrov
Verification: Alexander Parshin, Artem Titarenko


About comparison


Tested codecs:

Bitrates:

Number of sequences: 4

Number of experts: 50

Download MSU Subjective Comparison of Modern Video Codecs (32 pages in PDF, 1.38 MB)


Goal of subjective comparison


During last few years many comparisons of video, audio and image codecs were carried out by our Graphics & Media Lab at Moscow State University. All of them used objective metrics like PSNR, VQM or SSIM. This fact has raised reasonable questions on adequacy of objective measures to the subjectively perceived quality, which is the main parameter of a codec's performance. Goals of our assessment are subjective comparison of new versions of popular videocodecs, comparison of results with objective metrics and subjective assessment technology testing.

Main comparison parts:

  1. Subjective comparison of videocodecs.
  2. Comparison of results with objective metrics.


Subjective comparison


Main quality parameter for a codec - subjective impressions of a viewer of a compressed video. Latter is the main idea of subjective comparison methods - quality score for a compressed sequence is the average opinion of a group of experts on its quality (MOS, Mean Opinion Score).
There are lots of methodologies of subjective assessment, many of them are implemented in MSU Perceptual Video Quality tool that was used for the assessment. Our comparison is using SAMVIQ - method that was recently developed by EBU (European Broadcasting Union), PDF with the comparison contains its description. On a graph below you can see average MOS for all codecs, the higher the better. Probably, XviD results could be improved by switching on deblocking algorithm (this algorithm isn't used by default).

average MOS
Average MOS for all codecs

Following graph illustrates average MOS for each codec and bitrate and its' 95% confidence intervals.

average MOS
Average MOS for all codecs and bitrates


Evaluation of objective metrics


PSNR, VQM and SSIM were measured for each sequence with MSU Video Quality Measurement tool, description of these metrics can be found on this page. Note, that "VQM" metric refers to algorithm of Feng Xiao, not proposed by VQEG objective quality metric. The following graphs illustrate relation between subjective opinion and an objective metric: if set of points is close to a straight line, then the metric is adequate to the subjectively perceived quality (values of PSNR and SSIM were mapped on MOS scale, see PDF with the comparison for more details).

PSNR VQM
SSIM
On our test set SSIM was far more adequate to the subjective opinion than PSNR and VQM

Content of HTML version


  • Introduction
  • Gratitude
  • Comparison abstract
  • Overview
  • Rules and goals
  • Sequences
  • Codecs
  • Results of subjective comparison
  • Analysis of objective and subjective results
  • MOS+PSNR/bitrate graphs
  • MOS+PSNR graphs, grouped by bitrate
  • Evaluation of objective metrics
  • Correlation of objective metrics and subjective scores
  • Conclusions
  • Average MOS for all codecs
  • General conclusions

  • Download


    E-mail: 

    Call for codecs 2013
    See all MSU Video Codec Comparisons

    MSU video codecs comparisons resources:


    Other resources


    Video resources:

    Bookmark this page:   Add to Del.icio.us Add to Del.icio.us     Digg It Digg It     reddit reddit


     
    Last updated: 10-March-2011

    Search (Russian):
    Server size: 8069 files, 1215Mb (Server statistics)

    Project updated by
    Server Team and MSU Video Group


    Project sponsored by YUVsoft Corp.

    Project supported by MSU Graphics & Media Lab

    Rambler's Top100 [an error occurred while processing this directive] @Mail.ru