[x265] Slice decision (x264 vs x265)

[Rainer M. Engel]

... sorry for replying to my own mail..

Test between x.264 and x.265 against reference (ground truth).

Reference 848 scenes (slices)

x.264.........................................................
x.264 | --min-keyint 1 --keyint 999999 --scenecut 50
found 839 slices, 766 match with reference

x.264 | --min-keyint 1 --keyint 999999 --scenecut 100
found 910 slices, 774 match with reference


x.265.........................................................
x.265 | --keyint 999999 --scenecut 80
found 762 slices, 739 match with reference

x.265 | --min-keyint 1 --keyint 999999 --scenecut 60 --scenecut-bias 15
found 799 slices, 744 match with reference

x.265 | --min-keyint 1 --keyint 999999 --scenecut 100 --scenecut-bias 15
found 799 slices, 744 match with reference

x.265 | --min-keyint 1 --keyint 999999 --scenecut 100 --scenecut-bias 30
found 795 slices, 744 match with reference


In these first tests I focussed on flexibility in setting the parameters
and aimed on more positive false detections if this increases the match
count against reference. According to that x264 produces higher rates.
Do --scenecut and --scenecut-bias already work like expected or am I
missing something here?

Regards,
Rainer



Am 25.02.2017 um 19:05 schrieb Rainer:
> Hello everyone,
> 
> I'm new to this list and very interested in the "Slice decision options"
> of x265. The tests done so far show an expected behaviour of..
> 
> --open-gop
> which is enabled by default.
> 
> --keyint
> Setting this to a very high value, one which is higher than the duration
> of the longest shot, works fine. 
> 
> I run into problems by setting up the parameters to find all slices from
> my reference (ground truth containing any flavour of slice one can
> imagine:). Increasing "--scenecut" beyond the default of 40 brought no
> significant gain of more detected slices. Also increasing
> "--scenecut-bias" (as I understood correctly) wasn't of that big impact
> in the tests I've done so far. 
> 
> Are there some dependencies between parameters which are not that
> obvious here, at least to me? I also tried other parameters with no big
> impact.
> I hoped to get a feeling how the parameters work in concert, but the
> "aggressive" placement of slices by changing "--scenecut" values could
> not be reproduced here. Am I doing anything wrong? 
> 
> AIM:
> - individual slice detection by threshold, not interval
> - detect more false positives, than less 
> 
> CSV:
> - the csv log is used for comparing/counting the slices 
> 
> Any help, hint and reply on this is much appreciated.
> I use a MSVC build for Win-x64 found here http://x265.ru/en/builds/ on a
> YUV input clip. 
> 
> Best regards,
> Rainer
> 
> --
> Rainer M. Engel, Dipl. Digital Artist
> Berlin, Germany
>