The Joint Collaborative Team on Video Coding (jct-vc) of itu-t wp3/16 and iso/iec jtc 1/ sc 29/ wg 11 held its tenth meeting during 11-20 July 2012 at the City Conference Centre (ccc), a k. a

JCTVC-J0559 AHG6: Report of ALF viewing results [T. Yamakage]

Results for an informal subjective viewing for ALF are reported. This viewing is to compare Main profile and a proposal (JCTVC-J0390 Software package 2 on top of Main profile). Results showed that ALF currently shows visual improvements in a limited set of sequences. Out of 41 test cases, 3 showed ALF is better (confidence interval not including zero line == equal), 1 is worse.

Some additional sequences outside the common test set were used.

This indicates that ALF has no visual benefit as standalone tool, except for rare cases (2x Riverbed, 1x Kimono), worse in one case of BQ Terrace. With modified deblocking, it is likely that the problem with the Riverbed cases would be solved.

Comparison of 16 bit ALF version against the ALF of HM7 was not done, but it is assumed by ALF experts that no visual difference would be visible.

In case that ALF would be put into a profile of version 1, the current 16 bit version (“JCT-J0390 software 2”) should be adopted (plus remove padding as said elsewhere).

Otherwise, it should be removed and for potential future profiles further study should be performed, including study on limited bit precision (as future profiles may not necessarily need the 16 bit restriction)

Decision (SW): Adopt JCT-J0390 software 2 (plus the software for removal of padding as from BoG).