H264 Adaptive Q. mode explanation

[starcy]

Hi Elecard team.

I recently start to using H264 encoder, and i suprise with quality and speed.

Every option is known to me, except strengh of AQ, because can be a negative value.

Any suggestion?

I suppose, this is usual useful for low-mid bitrate encoding (500-1000kbps) but i am very confused about this settings, aslo how many is different between AQ modes (Luma, Contrast, Complex)

Thanks

[starcy]

Anybody to answer?

[Dmitry Teplyakov]

Sorry for the delay,

Adaptive Q allows you to use various quantizers  when quantizing. At that just one of three algorithms are used: Luminance, Contrast, Complexity. Each algorithm is based on analysis of brightness, contrast and complexity of macroblocks.

For each algorithm ‘strength’ is specified.  ‘strength’ is a conditional diapason of quantizers while quantazing  in a frame. The signs ‘+’ or ‘-’ in strength regulate  which quantizer will be used for a macroblock that has higher brightness, contrast or complexity.

Hope my explanation makes sense…

[starcy]

If I understood you correctly, using negative values for strength, will incrase quality on for example dark scenes, where encoder use mostly higher quants to low quants on that macroblock, and on scenes where use low quants will use higher quants?

[Dmitry Teplyakov]

at negative volumes of strength the maximal quantizer will be set to:
at the simpliest macroblocks (Complexity mode)
at the brightest  macroblocks (Luma mode)
at the most contrasting macroblocks (Chroma mode)

and, on the contrary, at positive volumes of strength the maximal quantizer will be at:
the most complex  macroblocks (Complexity mode)
the most dark macroblocks (Luma mode)

[starcy]

So i need to use negative values to incrase quality of dark scenes right?

I just need that answer : :idea: