VLC should support forced subs for DVD

I have been looking at this. Tested with Lotr:fotr

There are some forced subs at 1:15:00 trough 1:17:00 where some elvish is spoken. These are shown by Apple DVD player, even if I disable all subtitle tracks. These subs are alway English.

Analyzed with VLC and they seem to be in a separate track (pid in the "normal" subtitle range). I'm assuming we can only detect this track, by looking up the subtitle attributes for this track http://dvd.sourceforge.net/dvdinfo/ifo.html

The IFO subtitle attributes have an extension byte named SPRM #19 (closed). This can signal the following values: 0=not specified, 1=normal, 2=large, 3=children, 5=normal captions, 6=large captions, 7=childrens captions, 9=forced, 13=director comments, 14=large director comments, 15=director comments for children http://dvd.sourceforge.net/dvdinfo/sprm.html

This will need implementation in the DVDnav library.

changed title from Videolan Player should support forced subs for DVD to VLC should support forced subs for DVD

changed milestone to %1.1 feature freeze

See #2452 (closed)

changed milestone to %2.0 feature freeze

And still noone does care...

changed milestone to %Features paradize

No you dumbasses! This is an important feature. Let me get this straight: You just moved it to the "features paradize" graveyard just because nobody has taken interest yet? Didn't it cross your mind that now that it has been moved there, nobody will EVER care, because nobody will see it?

Anyway, why not move all the unassigned "1.2 Feature Freeze" tickers to "Features paradize", and all unassigned "1.2 Bugs" to "Bugs Paradize", and ship 1.2 tomorrow? What's the point of having milestones if you scrap all the major targets of said milestone, and implement only the minor stuff that could have been shipped as point releases?

There are the joys of open source for you.

VLC: 13 years since the introduction of the DVD-Video format, and we still don't have a complete implementation(tm)

PS: No I can't submit a patch because nobody has ever produced a guide to introduce newcomers to VLC's codebase

Original author: kurkosdr

@kurkosdr: 1) An infantile reply isn't really going to help in any case.

The importance of a thing is really opinable (for example I really didn't consider DVD support important at all although it is nice to have it).
The milestone isn't really an absolute thing, a developer can fix things in "Features paradize"/"Bug paradize" (I have seen it happens) and developers aren't paid.

PS: If you pay a developer you can see a feature implement immediately, but you should avoid infantile replies :D

Well, after getting my own copy of VLC source as well as libdvdnav source, I had a smalll digg:

dvdnav.c has the following function:

uint16_t dvdnav_spu_stream_to_lang(dvdnav_t *this, uint8_t stream) {
  subp_attr_t  attr;

  if(!this->started) {
    printerr("Virtual DVD machine not started.");
    return -1;
  }

  pthread_mutex_lock(&this->vm_lock);
  attr = vm_get_subp_attr(this->vm, stream);
  pthread_mutex_unlock(&this->vm_lock);

  if(attr.type != 1)
    return 0xffff;

  return attr.lang_code;
}

Question: IS this the place where it all happens? I see in VLC source that if that function is called and it is returning 0xffff the stream is not used. If this "1" here is indeed the type of the attribute you are talking of, why not also allow "9" here and return the language code?

Wouldn't then the subtitle track register with VLC and be available in the menu?

However, then we still have no info that this is a "forced" subtitle track. I think the two-digit language code is all that is passed to VLC and VLC then maps this to fancy language names.

So possible would be:

patch libdvdnav to also return "9"-type subtitles
patch libdvdnav to provide a function "is this track forced" - by looking at the code in dvdnav.c, this seems feasible to me

I have read elsewhere that libdvdnav can be told to automatically show forced subs if none selected, but I highly doubt this.

Is there someone who has a DVD with test material? and a VLC source tree with contribs where he could add a simple

&& attr.type != 9

to the if-statement in dvdnav.c and see if VLC picks up MORE subtitle tracks? I have sold my LOTR:FOTR DVD when switching to BlueRay.

I do not know if VLC has the ability to add some strings to track names, which can be passed from access modules. btw. I have not found a decent developer introduction as to how the code is structured at all, very hard to get an overview what happens where and why...

I think this is part of a more general problem, that VLC doesn't support forced subs in any container (MKV, MP4 etc).

Here is a really easy solution: Just make VLC detect the forced subtitle track (in VOB, MKV and MP4 containers), and then create a new language called "(forced)" and have it as default in the "Subtitles and OSD" settings.

A little harder solution, but a bit better:

-Currently VLC does the folowing: If no external subtitle exists, try to find an internal subtitle track that matches the default language (as set in "subtitles and OSD"). If no such track exists, select no subtitle.

-Here is the fix: If no external subtitle exists, try to find an internal subtitle track that matches the default language (as set in "subtitles and OSD"). If no such track exists, try to find a forced subtitles track. If no such track exists, select no subtitle.

This should be really easy to implement. Much easier than trying to do it by modifying nav, and it would be a more general solution.

PS: Please reply if you didn't understood my fix for further explanations.

PPS: Why VLC doesn't have a drop-down menu for selecting default subtitle track? MKV merge has a really nice list with lots of languages you could use.

Original author: pic889

This is not exactly true. VLC supports forced subs if the track is set as enabled+default in MKV, especially in 2.0.3.

About libdvdnav, if we have the info exported, it could be fixed in VLC, but so far, I have not seen that.

@pic889

A dvd can have more than one language of forced subs.

but i agree this is a huge omission.

District9 is a good DVD for this.

I don't know about DVDs but this is still an issue for Blu-rays. It's been bugging me for years from Breaking Bad to Game of Thrones, and now even certain scenes from The Crown.

I spoke to a couple of guys at the VLC FOSDEM stand last weekend, sorry I don't know who they were, but they seemed surprised that this was not working for me and urged me to file a bug if it really was still an issue. I hadn't looked this bug up previously as I believed it was actually a libbluray issue. By the sound of it, the necessary code may be missing from both libbluray and VLC. I know that forced subtitles also do not work in MPV but that may also be because it doesn't support menus.

DVD and Blurays are very very different, in this regard. So new bugreport, if you want.

added Component::Input: optical media label

However, there are several things to it and none are existing:

establish the concept of „forced subs“ in videolan UI - it is Not there Right now - e.g. what language should be used?
implementation via libbluray
implementation via libdvdnav
implementation in other formats? MKV?

mentioned in issue #2452 (closed)

mentioned in issue #14405 (closed)

VLC should support forced subs for DVD

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