DVD Specifications

[EuropeanMan]

I hope this is the right forum...

Where can I find information on DVD Specs...

For example, SPECIFICALLY...I'd like to know if the "Root Menu" of a DVD (NTSC/PAL) must have a subtitle stream, and WHY...

Thanks in advance...

Reason why is that I've encoded a movie and made my own menu...and when I open this VIDEO_TS folder in PGCEdit, it says a subtitle stream must be 'defined'...

[setarip_old]

Hi!

Reason why is that I've encoded a movie and made my own menu...Does it play properly (standalone player and software player)?

[EuropeanMan]

^ yes of course it does...but i want to know if there is a SPECIFICATION as such for a DVD ROOT MENU to have a subtitle stream present..that's all. AND if it DOES, I'd like to see documentation.

[setarip_old]

yes of course it doesMind-reading is not a requirement for trying to aid those who post questions ;>}

Nothing in your initial post indicates that your homebrewn DVD actually played...

[mpucoder]

^ yes of course it does...but i want to know if there is a SPECIFICATION as such for a DVD ROOT MENU to have a subtitle stream present..that's all. AND if it DOES, I'd like to see documentation.
Yes it does, in fact, according to the hard-to-get specification, any menu is required to have 1 and only 1 subpicture stream. But the spec over-uses the term "stream". In this sense "stream" means a group of encoded streams for different display modes that are related and referenced together. (DVD Specifications for Read-Only Disc, Part 3 Video Specifications, 4.2.1 BP 340 "When VTSM VOBs exist, the number of Subpicture Streams should be '1' ")

[rik1138]

Does it specifically say 'should be 1', or 'should not be more than 1'... Does it give more specific details? *Looks for spec book... in storage damn it...* :rolleyes: I can't imagine this ever causing a problem in a player (not having a stream), but since the intent of the spec was for menu space to hold _menus_, the authors assumed that functionality would be the only purpose, and as such, 'should' have a subpicture stream.

I know you can't have more than one (well, you can't access more than one), but having a still or video with no subpicture streams is quite common, and I've never heard of it causing a problem on a player. Things like intro animations and transitions frequently don't have subpicture streams on them, even on A-list Hollywood titles.

But, as mentioned, the purpose of the subpicture is the graphics used for the buttons. If you want a button on the video (even an invisible one), you need a subpicture stream. If you just want to play a piece of video in 'menu space', you don't need to have the subpicture stream...

From your example 'I've encoded my own menu', if you want that menu to 'work', you will need a subpicture stream... Do you have buttons on the menu? If you do (and they work), then you have a subpicture stream. When it's saying it needs to be 'defined', maybe it means the language of the subpicture stream? In general, this doesn't matter, but I noticed a while back that Scenarist changed from always defaulting menus to 'not-specified' to 'English' as the default menu subpicture language. I'm not sure why this matters, but that might be what PGCEdit is complaining about...

[mpucoder]

The spec is referring to the ifo declaration of subpicture streams. Even in menus with transitions there eventually should be a menu with buttons, therefore the ifo will define the stream.
btw, you can have more than one stream (or set of streams) in the VOBs, but each menu can use only one. Also the ifo will define only one (with no language)(there is only one slot for menu subpicture attributes in the ifo). This allows for different subpictures for different language units (the PGC is where the mapping to VOB stream numbers takes place).

I doubt the absence of a subpicture stream would cause any problems, but it isn't spec, so it could if the player was strict.
However if highlights (button hotspots) are present there must be a corresponding subpicture.

Menu subpicture stream attributes (again, in the ifo) have no language (but menus do as they belong to a language unit)

[rik1138]

The spec is referring to the ifo declaration of subpicture streams. Even in menus with transitions there eventually should be a menu with buttons, therefore the ifo will define the stream.

Well, in the case I'm referring to the intro and transitions are separate pieces of video (separate PGCs) that just play and then jump to the PGC with the menu and active buttons...

I've also seen menu space used to store actual video clips when the author doesn't want the resume information of the main video to be lost. That way you can menu out of a feature, play a few other video clips, and resume back to the feature exactly where you left...

You can, of course, just put a dummy subpicture on everything so it's always there. I've seen people do that too...

Menu subpicture stream attributes (again, in the ifo) have no language (but menus do as they belong to a language unit)

Yeah, that's interesting... I never bothered to look, but you can assign a language to the audio and subpicture streams in Scenarist (even for assets used in menu space), and you can see those languages selected in the PGCs in menu space... But when I open the IFO in IFOEdit, it shows 'Not Specified' for them both... I guess that information really isn't used. I suppose it's there because when you are building a Track in Scenarist, it doesn't know where you intend to use it yet... I've seen players report the 'language' of a menu, but it's probably just reading what language unit it's playing...

[mpucoder]

Yeah, that's interesting... I never bothered to look, but you can assign a language to the audio and subpicture streams in Scenarist (even for assets used in menu space), and you can see those languages selected in the PGCs in menu space... But when I open the IFO in IFOEdit, it shows 'Not Specified' for them both... I guess that information really isn't used. I suppose it's there because when you are building a Track in Scenarist, it doesn't know where you intend to use it yet...

Right, Scenarist and most others associate a language with every stream which is then used to determine which streams belong to each language unit.

[Ghitulescu]

... I'd like to see documentation.

No problem, fork 5000$ to http://www.dvdfllc.co.jp/format/f_nosbsc.html and you can see the specs with your own eyes.

[EuropeanMan]

^ LOL - thanks alot Ghitu...that's what I wanted to see! :) And thanks to mpucoder for answering my question...much appreciated.

Wonder why a free list of DVD Specs isn't readily available in a PDF for something :(

[rik1138]

No problem, fork 5000$ to http://www.dvdfllc.co.jp/format/f_nosbsc.html and you can see the specs with your own eyes.

Wow, it's still that much? I figured they'd at least lower the price... The Blu-ray books are cheaper, although you have to get a couple of them to be complete, and I think they charge per book...

[Ghitulescu]

Wonder why a free list of DVD Specs isn't readily available in a PDF for something :(

One having access to the doom9's forum also has access to google (or any other search engine) and would find the answer in the first 10 hits, but not as PDF I'm afraid. Pgcedit also points to relevant web pages if one is in doubt about a particular issue.

Besides, free info is not always 100% accurate, being mostly obtained using observations, commercial software behaviors and their documentation (scenarist & co), DVD players behaviors, reverse engineering, patents and standards, and probably sneak peeks in the "forbidden books". The standard itself is sometimes unclear or self-contradicting, or simply lets the manufacturer the choice of a particular implementation. This is why a serious publisher usually tests the DVD against a "farm" of DVD players (in addition to the software analysers), just to be sure.