Why do some Blu-Ray 4K UHD Discs have more than one video file?

[tnuhnivad]

On my copy of the 4K Avatar release there are two seemingly exactly the same video files.



I pulled both files over to my PC and again I cannot tell a difference between them in any way? Whats the point of including more than one of these extra large files on the disc? Is it safe to delete one of the files?

[nissling]

The disc is constructed of a set of audio and video files which are structured in such a way that you can create multiple titles with the same source. This is primarily used in case various versions of the same film is to be used on the same disc without taking up more data than necessarily. This is great for having both theatrical and extended cuts on the same disc.

You'll see this a lot on Disney titles as they have hard coded titles for various languages. I once ripped the Mexican version of Inside Out by mistake, as it's on the American UHD-BD and looks identical to the US version when viewed in MakeMKV. Apart from that there may have been a slight change for Avatar in one of the three other regions (Mexico, Canada or Japan) and could've been carried over to the UHD.

[Radiocomms237]

From this disc's entry on TheDiscDB it appears to have two main playlist files:

00800.mpls with the following segment map:

Code: Select all

62,107,71,108,73,109,75,125,69,110,78,111,80,112,82,113,84,114,86,115,88,116,90,117,92,118,94,119,96,120,98,121,100,122,102,123,104,124,106

and 00801.mpls with this segment map:

Code: Select all

62,70,71,72,73,74,75,76,69,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106

Assuming both files have the exact same runtimes and chapters, I'd guess they may be different language versions?

If you're working from a decrypted backup you could play some of the differing segments on your PC directly from the STREAMS folder, for example, you might play 00107.m2ts and 00070.m2ts to see if you can spot any difference (as they're right at the beginning of the movie I'd hazard a guess that they may be the movie's opening titles for alternate regions)?

Quite often the 00800.mpls file is the English language version (or the US version, or the Theatrical version) of a movie, and 00801.mpls, 00802.mpls, etc. are alternate versions, but it never hurts to double-check!

Sometimes the differences can be really hard to find, for example, there may be an English version using US spelling and an English version using UK spelling!

The only shadow of doubt cast over the above theory is that, in this particular case, I know "Avatar (2009)" has (at least) three different cuts available (according to IMDb):

Theatrical: 162 min (02:41:41)*
Special Edition: 171 min (02:50:34)*
Extended Cut: 178 min (02:58:09)*

* The runtimes in brackets are from my own Blu-ray versions of the movie.

But if you say the runtimes of the files on the disc you have are identical than it likely isn't a different cut? Plus, nobody has reported more than one cut as being available on UltraHD (and I would've thought we'd hear about it if there were)!

[tnuhnivad]

Thanks for the useful information y'all. I've watch a good bit of the files to see if I can spot a difference. Again, I didnt change any selections before ripping both files. The only difference I've spotted is the 8001 file has the forced themed yellow subtitles during conversations amongst the Na'vi in their native language and oddly has a slightly smaller file size.

[Radiocomms237]

It's also interesting that your Theatrical version is 21 seconds longer than mine.

I can only assume that yours must have an additional/different distributor/production company's splash screen at the beginning and/or end? (I don't recall what my copy has either.)

[flashback8]

The only difference I've spotted is the 8001 file has the forced themed yellow subtitles during conversations amongst the Na'vi in their native language and oddly has a slightly smaller file size.

That's normal. Because different clips are used in the playlists, the sizes will be slightly different.

[soulshadow]

So I'm working with the Blu-Ray version, but it's the same story, mpls800 and mpls801 appear exactly the same except for baked in forced english subtitles. On my disc mpls800 has the english baked in and 801 does not. The easiest way to compare that I've found is at the start of chapter 4, appox 00:08:55. One version (800) includes the text "One Year Later" while the other doesn't. The entire credits sequence is identical, so I doubt there's any other differences between the two playlists.