First of all: do we need another, new, audio video container? Well, before I thought about these things, I didn’t think so…
There are some features which are not implemented (yet?) that could be useful, in particular for movies, and their avid collectors.
Let’s start with the obvious points:
1) It should be open source
2) It must be able to contain every open source audio video subs codecs
3) Everything should be contained in one file
and now the new features:
4) Menu support: I’m aware that MP4 has a basic menu support, and MKV has plans to introduce it – and almost everything that a menu do could be done via the player interface; but a DVD-like kind of menu could still be a welcome addition; it could be quite simple and must be compatible with software and hardware players – at the contrary of what happens with BD menus
5) Multiple luma/chroma planes: different possible combinations of luma and chroma planes that could be used, for example, to have different color gradings, or different contrast/brigthness – like Mad Max: Fury Road Black & Chrome edition, that is NOT simply the color version desaturated… I know that it’s possible to do something similar using different video tracks, but with this method, to have a movie with two color gradings will take twice the space, while with 1 luma and 2 chroma planes it will take only 33% more space (at max, 4:2:0)
6) Matte mask: to allow an open matte, and a letterboxed version in the same file – I know for sure that is possible to do that via a modified subtitle, but it’s always a trick; it will be great to have a “matte” option in the proper menu, and in the software settings
7) Video objects: a sort of seamless branching, but aimed to eventually replace just part of the image – for example, main titles are overlaid on the movie, and use the same language of the selected audio track, or allow to add or replace characters, vehicles, monsters etc. – like Jabba in EP4…
8) Joint audio/subs/titles/branch actions: if the user select a given language, a given subtitle track (for example forced) are selected, along with the eventual proper titles, credits, shots
9) Discrete dialogs: the main track is without dialogs, and they are added “on the fly” on the right channels; so every track for a different language will contain only dialogs, and the size could be greatly reduced; its also possible to have more sound only tracks, and more effects track.
10) Seamless branching and angles: present on DVD and BD, don’t know if any single file container has implemented them yet; great opportunity to have two or more cuts on the same file; combined with different luma/chroma planes, we could have, for example, a theater cut, and a director’s cut with added/cut scenes, different contrast and color grading
11) Audio or video random branching: allowing to play a certain shot/scene at random; an interesting way to watch a movie that will be never the same every time; for example, selecting different takes of the same shot, or characters, or just dialog.
I don’t know if some (of all) of these features are possible, but I think so; if they will be implemented, the way we could watch a movie will certainly be changed…
Of course one could also think that studios will never adopt this container; they will not lose the chance to release multiple times the same title with just a slightly different color grading, improved master, new audio mix… but I think they will sell more if the latest edition will include all the previous ones, all in just one file!