Avisynth script help?

[PeterNL]

I need to get the max Y-value per frame and just got stuck with all that runtime stuff.

So, how do I get a variable for the maximim Y value and (depending on that variable) do something to the clip:

if Y > 16 --> autolevel

else

--> do nothing

[poisondeathray]

Runtime filters (eg AverageLuma, YPlaneMax) can only be used with runtime functions (eg conditional filter, scriptclip)

src=last

src
#your filter here
filtered=last

ConditionalFilter(src, filtered, src, "YPlaneMax", ">", "16", show=true)

Just replace #your filter here, with whatever filter e.g. autolevels() . To debug it , use show=true to show the value of the conditional. You might have to adjust the 16 value slightly. Change it to show=false for the real thing

[PeterNL]

Thanks poisondeathray!

It works. Not perfect but result is much better than before. The problem I'm having with all "autolevels" scripts/plugins is that they also
"crank-up" black fades and crossfades, which looks really bad.
After setting the Y-level to 40 almost every frame in the fade/crossfade remains dark except a few at the start and end.
I can live with that though.

Thanks again for your help!

[poisondeathray]

Have you tried the other "autolevels" plugins ? (there are a few variations of "autolevels", and a different one called "autogain" by lato) . Lato's works the best overall IMO, but "auto" anything is prone to problems in general . It has a dark_exclude parameter which allows you to exclude a percentage of the darkest pixels in the minima calulation

[PeterNL]

I tried all of them. From ColorTuv(autogain=true) to several VD-filters. Also Lato's.
They all fail when handling fades-in or crossfades thru black.

But when using your script and setting the minY level to 75, the results are quite acceptable.

Thanks again PDR!

[newpball]

PeterNL, out of curiosity why do you need this?

[PeterNL]

I got some old super8 homevideos laserscanned to lossless AVI.
The luma-levels are not constant and vary a lot because of the lousy camera i had at that time
Beside that, I will put them only on my Dune mediaplayer so there is no need for studio-levels either and I prefer 0-255 levels.
Doing this manually is a nogo so autolevels is my way to go.
I edit them, render the complete project to some lossless codec and push them thru avisynth/virtualdub to get the right levels which worked well, except for the fades/crossfades. Finally I render to X264.