MeGUI and Adaptive Q parms: Any chance ?

[akupenguin]

correct me if im wrong, but rising the deblocking settings will compromise picture sharpness too.
Right, exactly the same as modifying the CQM to raise QP per bit. Except that modifying the QP per bit also confuses x264's other decisions, whereas deblocking settings only affect deblocking.

[woah!]

heres the 4 encodes of the intro for you to compare overall quality as screenshots dont tell the whole story most of the time:

720P_INTRO_EQM AVC-HR_1000BR_AQ_0.4_10.mkv
720P_INTRO_EQM AVC-HR_1000BR.CFG.mkv
720P_INTRO_M4G-V3.CFG_1000BR.CFG.mkv
720P_INTRO_Prestige_1000BR.cfg.mkv

encodes.rar (http://www.cif-forums.com/png/encodes.rar)

[Sharktooth]

Right, exactly the same as modifying the CQM to raise QP per bit. Except that modifying the QP per bit also confuses x264's other decisions, whereas deblocking settings only affect deblocking.
well the idea is exactly to force the encoder to make it assign more bits in flat areas since there is an unwanted blocking. the counter-effect is those bits should be reclaimed from other "places" but in most cases the blocking is the worst hurting thing in the picture.
i think this method is more coherent than AQ (that's assigning more bits only in blue or dark areas without distinction of flat or detailed areas) but perhaps there's a problem in x264 since this "blocking" problem seems to require workarounds for many sources.

[akupenguin]

Of course a CQM changes the distribution of bits. But what it shouldn't do is
since the matrix forces the encoder to put more bits than flat for every quantizer that will rise the QP for each encoded picture. doing that, the deblocking filter will be triggered more frequently

[Dark Shikari]

heres the 4 encodes of the intro for you to compare overall quality as screenshots dont tell the whole story most of the time:

720P_INTRO_EQM AVC-HR_1000BR_AQ_0.4_10.mkv
720P_INTRO_EQM AVC-HR_1000BR.CFG.mkv
720P_INTRO_M4G-V3.CFG_1000BR.CFG.mkv
720P_INTRO_Prestige_1000BR.cfg.mkv

encodes.rar (http://www.cif-forums.com/png/encodes.rar)
I tested these blindly with the MSU Human Visual Quality tester. Results:

Task method, Continuous quality evaluation (MSUCQE)
Method description, Two videos are shown simultaneously. During playback expert should click on video he or she dislikes at the moment.
Mark description, Mark belongs from 0 to 10, the higher the better. In pair of sequences if expert clicked on first one c1 times and on second c2 times, first sequence gets mark (10.0 * c2/(c1+c2)) and second gets (10.0 * c1(c1+c2)) or both get 5.0 if no clicks were made.

AVERAGE MARKS
720P_INTRO_EQM AVC-HR_1000BR.CFG
7.40

720P_INTRO_EQM AVC-HR_1000BR_AQ_0.4_10
9.02

720P_INTRO_M4G-V3.CFG_1000BR.CFG
5.57

720P_INTRO_Prestige_1000BR.cfg
0.02

Simple conclusion: these matrices (M4G and Prestige) tend to look worse at low bitrates, and AQ is good.

[Sharktooth]

EQM AVC-HR was not meant to be used at those bitrates...
it would be useful to have the flat matrix in that comparison too

[foxyshadis]

Sharktooth, would you care to rescale the matrix from the original coefficients to make it give approximately the same bitrate per quant? Call it the balanced version or something, I don't know.

[Sharktooth]

yes, however it depends on the source too... but i have the suspect the actual AVC-HR will look better...

[foxyshadis]

whoa, would you be willing try another encode, this time with m4g-smooth? Its scaling is a little more stronger than eqm-hr and I'd just like to see if it makes any visual difference.