[x265] Slice decision (x264 vs x265)

[Divya Manivannan]

The expected behavior is the number of I-slices will increase with increase
in scenecut-bias.

How are you identifying the reference (ground truth)?

Thanks,
Divya M.

On Tue, Feb 28, 2017 at 8:33 PM, Rainer M. Engel <engel at endime.de> wrote:

> ... 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
> >
>
> _______________________________________________
> x265-devel mailing list
> x265-devel at videolan.org
> https://mailman.videolan.org/listinfo/x265-devel
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.videolan.org/pipermail/x265-devel/attachments/20170301/4d136f86/attachment.html>