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Configuring playback to crop black bars for use with an anamorphic lens

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mattkhan:
just revisiting zooming black bars away


--- Quote from: Hendrik on October 16, 2021, 02:40:12 am ---Right Click during Playback, the Window menu. If I take a typical cinema movie in 2.35:1 with letterboxing (eg. 16:9 in 1920x1080 or 3840x2160):

- Crop Black Bars -> 2.35
- Crop Black Bars -> Untick "Crop Sides of Video to Fill Screen"

This should just allow the video to fill the screen if there is room without any bad cropping or scaling.

--- End quote ---
the "Crop Sides of Video to Fill Screen" option behaves v erratically

it appears that the tag saved for the above is

    "Playback Info": "(1:1)(11:AspectRatio)(36:(1:4)(1:0)(1:0)(7:1310767)(1:0)(1:0))"

if I paste this into an item and click play, it zooms the black bars away and the option is checked

if I then start playback and check that item via the UI, the zoom changes
if I uncheck it (via the ui), the zoom disappears completely and I'm back to having black bars
stop playback and start it again, it's zooming again as expected

I'd think this must be a bug

Hendrik:
I can't reproduce this, with that info copy-pasted the option starts off (its the second to last zero), and toggling it on doesn't change the image even on my ultra-wide resolution, since the sides are not being cropped anyway.

mattkhan:
(split to new thread)

I remembered discussing this in the past and thought I'd found the right post, is this not the right way to do it?

i.e. equivalent of madvr zoom'ing away black bars and changing the aspect ratio (for subsequent correction by an anamorphic lens)

EDIT: actually it's probably this post/thread - https://yabb.jriver.com/interact/index.php/topic,131214.msg923650.html#msg923650

just to recap from that thread



--- Quote from: mattkhan on June 16, 2022, 05:13:35 pm ---1) Set Aspect Ratio Correction in advanced options + set Window > Crop in the right click menu during playback
2) Don't see any advanced options, use the Window menu only with Stretch + Crop Black Bars > Video within Black Bars is 2.35

--- End quote ---
I think the former would require use of zones which, given that I already use zones for DSP config, is unpleasant (small combinatorial explosion in no of zones... NB: this is a longstanding problem with zones for me, they're too "big", it would be better to be able to override just some particular bit of config)

Hendrik notes in the other thread that stretch is "dumb" in that it blindly stretches as you tell it to, I suspect that this will be ok though if it's driven by black bar detection as that detection, if it detected correctly, has the brains and so stretch and just do as it is told.

and one other point I notice there


--- Quote from: Hendrik on June 16, 2022, 10:47:03 pm ---I don't think video playback settings are synced across devices, but i'm not 100% right now.

--- End quote ---
they do appear to be (confirming, if it needed to be confirmed, that this needs to be supported by jrvr profiles)

mattkhan:

--- Quote from: Hendrik on April 23, 2023, 05:14:24 pm ---I can't reproduce this, with that info copy-pasted the option starts off (its the second to last zero), and toggling it on doesn't change the image even on my ultra-wide resolution, since the sides are not being cropped anyway.

--- End quote ---
I was testing with a 30.0.87 linux client (so streamed from server) with a 1080p screen, it definitely zooms with those config options

on a 31.0.2 windows client playing the file directly to a 4k screen, it does not zoom with same options

options > video > advanced has nothing set for aspect ratio correction in either case

Hendrik:

--- Quote from: mattkhan on April 24, 2023, 02:43:13 am ---Hendrik notes in the other thread that stretch is "dumb" in that it blindly stretches as you tell it to, I suspect that this will be ok though if it's driven by black bar detection as that detection, if it detected correctly, has the brains and so stretch and just do as it is told.

--- End quote ---

You should never use stretch, really, unless you very carefully selected your videos and all other settings, as its not designed to retain the proper aspect ratio.
With black bar cropping set properly, even today, preserve aspect ratio should just do the job, safely. Right now black bar cropping is just entirely manual, per video, and limited to a few presets. (well, depending on what you are after, both Preserve and Crop can be valid, depending on if you want constant width or constant height, showing all image content or never showing black bars)

If you throw in anamorphic rendering, you get other concerns of course. I don't assume you just setup a custom resolution with the right aspect ratio, but rather need actually "distorted" output in a standard resolution, so the lens can un-distort it? Which I believe is also possible today, just not very intuitive in the options.

Note that I'm likely to look at how all of these interact as I add support for automatic black bar cropping, and maybe move/duplicate some of it into JRVR profiles. I imagine the existing "aspect ratio override" option sees very little use, because its from a time when screens had non-square pixel, and the descriptions it uses still reflect that. Not many would ever get to the conclusion that it can be used for anamorphic lenses, although thats really quite the same thing as a display with non-square pixel.

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