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3D bluray mkv letterboxing

Posted: Tue May 15, 2018 4:32 am
by buttabean
I noticed recently that playback of ripped 3d frame packed movies have an issue with playing back in 2D where the aspect ratio changes, scene to scene. Is this a bug? Or a known issue? Any marvel movie with the opening title sequence will show what i mean.

I searched to see if anyone had this issue but nothing came up.

Re: 3D bluray mkv letterboxing

Posted: Tue May 15, 2018 4:39 am
by buttabean
1.png
1.png (3.19 MiB) Viewed 21532 times
Pic 1 shows the letterbox correctly, then is movies to this position in pic 2

Re: 3D bluray mkv letterboxing

Posted: Sun May 20, 2018 9:40 pm
by buttabean
I attempted to rerip the first captain america without the 3d frame and it also did the same thing with a older version of makemkv. 1.10 i think. So i guess this is an issue with 3d movies which do not allow 2D playback on bluray players i'm thinking.

Re: 3D bluray mkv letterboxing

Posted: Tue May 29, 2018 12:19 am
by preserve
Not a big. You are only seeing one eye when you watch it in 2D. Depending on the distance, you'll get horizontal offset like that. A 3D disc really isn't meant for watching in 2D. That's why 3D movies, except for some of the earliest ones, always come in a combo pack together with the regular Blu-ray.

Re: 3D bluray mkv letterboxing

Posted: Thu May 31, 2018 12:33 pm
by LuekG
Expanding on what was said above;

This is perfectly normal for a 3D Bluray especially with a movie that was post converted into 3D.

Sometimes with 3D photography the parallax needs to be corrected for more comfortable viewing. With parallax correction, the images will need to be cropped so that objects at the edge of the screen don't appear only in one eye's view but not the other, which can cause discomfort to the viewer, whose brain goes, "wtf? I'm only seeing object x at the edge of the screen with one eye but not the other.

As you watch it in 3D each eye is sent different information and you don't notice it cause your brain does it automatically, but your eyes move independently left and right dependent on what is being shown on the screen to trick the brain into the illusion of depth on a flat surface.

Depending on the depth and initial framing both the left and right images will move left and right leaving a black void (as pointed out) on the edge of the screen.

Some older post conversions are a lot worse. Beowulf, A Christmas Carol, Clash of the Titans and Alice in Wonderland are horrendous for this.

You will have the issue from time to time on native 3D, but not as much as usually they film with this in mind and are able to crop it in post production.

If you have an overscan option on your display, it's best you use it when watching 3D films directly converted to 2D as neither the left or right image will remain static.

Re: 3D bluray mkv letterboxing

Posted: Wed Jun 06, 2018 9:12 pm
by buttabean
Thanks for the details response Luekg. I wasn't aware that this is primarily a 2D to 3D conversion artifact. I figured since it was only noticeable on the left that maybe it was related to one of the channel creating the depth effect which was possibly the left channel since the right side never moved. Good to know i'm totally wrong :). I'll have to check those titles out and compare. Thanks again

Re: 3D bluray mkv letterboxing

Posted: Thu Jun 07, 2018 6:49 pm
by buttabean
I ended up ripping a movie that offered 2d playback on the same disk and noticed that there's two playlists. One is the 3D segment map which has pairs and the other doesn't have 3D as an option which doesn't have paired segments.

Re: 3D bluray mkv letterboxing

Posted: Sat Mar 13, 2021 4:20 pm
by preserve
Super old thread, but I figured I'd add this for clarification, and for anyone randomly running across this topic via Google.

There are 3 options when it comes to playing 3D Blu-rays as 2D:

- In the screenshot shown above for My Bloody Valentine, you can see that the 2D playlist is using just one eye of the 3D segments. So you're not getting the original 2D movie, but you can watch the movie this way in 2D if you don't care. (In this Jurassic Park example comparing one 3D eye to the original 2D film, look at wisps of hair removed from Ellie and Malcolm's heads, the background being zoomed in, the foreground seat cushion being stretched, and heavy DNR.)

- The second option is that the disc will put both the 3D version and the 2D version on the same disc, all with their own separate segments. This is the least desirable option because it probably means that the 3D version was more compressed than it otherwise would have been, to make room for the 2D version.

- And the third and best option is when movies include the 2D version on its own separate disc.