default and forced track flags for matroska subtitles

[ranpha]

Originally Posted by Chetwood

I do understand English but being no native speaker, some actors are hard to understand so I always rip the movie with English subs as well and usually watch English/English. With friends we either watch English/German or German/none (some are too lazy to read subs and prefer the dubbed version).

Well, that's why the closed-caption track will come in play.

[Chetwood]

Originally Posted by ranpha

Well, that's why the closed-caption track will come in play.

Why closed-caption when I can use the regular subs just as well? I'm still not convinced that's the right term for any BD sub.

Originally Posted by sneaker_ger

I'm saying that with your examples the Elbish dialog is included in at least two tracks, with one of them being marked as a forced track inside Matroska. That means when you select the non-forced track, a player following the Matroska spec will display the Elbish dialog twice, because it mustn't unselect the forced track ever but will have to display both tracks simultaneously.

I'm not sure I understand what you mean. What in the specs makes you think that the manual selection of a track during playback should be overwritten by any flag of the container? When you start playback, the player selects the sub according to the flags of the container but the moment you cycle to another sub, only the selected one has to be displayed.

How about you check this sample and tell us if it's compliant and how you think it should be played back.

Originally Posted by sneaker_ger

A Blu-Ray or DVD player cannot automatically select the correct subtitle without parsing the menu.

Of course it can by parsing the IFO. All my DVDs and BDs are ripped without a menu. I can use the SETSTN command to make the DVD play back the track that I want (which a standalone can choose to ignore). I also don't see the relevance in your distinction between subtitle lines and tracks. If there's no menu/navigational commands, the player will fall back to the flags of the PGS stream, YMMV.

[sneaker_ger]

Originally Posted by ranpha

I think you have just replaced the functionality of a menu with what of a playlist. We are not talking about computer-based players that doesn't have Blu-ray menu support here

Let me get this straight: you are trying to proof your point by saying that players with menu support do correctly and automatically select the correct tracks/playlists? That's an argument supporting my stance - not yours.

And no, without parsing the menu you don't even know what the "main playlist" is. Players without menu support (like LAV) usually just load the longest playlist, but that does not always work correctly and may require manual interference. For example a making-of might be longer than the main movie.

Originally Posted by ranpha

Please do not drag the MPC-HC + LAV Splitter Source combination here. Both are not smart enough yet to automatically select the correct subtitles yet in a BD disc.

Yes, because they do not parse the menus. Nev would've long since implemented correct automatic track/playlist selection for Blu-Ray if it would be possible without parsing the menus.

Originally Posted by ranpha

BTW, look at what I have said before and think about it:

PGS subtitles tracks doesn't have the forced flag option, more often than not, forced lines are line-based, not track-based, unlike DVDs.

Yes, I know that and wrote so more than once. Both DVDs and Blu-Rays have the concept of forced lines. Saying "more often than not" is meaningless in this context. That's like saying "more often than not, Blu-Rays use DTS instead of AC3, unlike DVDs". It does not tell us anything about the automatic selection.

Originally Posted by ranpha

Try it with KMPlayer, you will see ONLY ONE Elvish line. Actually, there are TWO of them, but you will only see one. This doesn't work with OCR-ed DVD subtitles of course, which is a flaw in the implementation.

No, that is not a flaw in the implementation. You rely on players behaving in a way that is not described in the specs. Then you call your non-spec-behavior "canon" and complain when it doesn't work.

Originally Posted by ranpha

If you do this in MPC-HC, naturally you will see ONLY ONE Elvish line. Mainly because the forced track isn't loaded when the player is supposed to load it.

Yes, I know. But the Matroska specs have nothing to do with MPC-HC, DirectShow or any other specific framework/player. If a framework is limited in a certain way it does not change the Matroska specs.

Originally Posted by ranpha

If course I mean what I said. You never rip BDs with forced subtitles right?

It looks like this:


Several English audio and subtitle tracks. No information about what is what. Also, the option to only extract forced lines does not guarantee that the alien language lines are actually marked as forced, so you might end up with an empty "forced" track.

Originally Posted by Chetwood

Of course it can by parsing the IFO. All my DVDs and BDs are ripped without a menu. I can use the SETSTN command to make the DVD play back the track that I want (which a standalone can choose to ignore). I also don't see the relevance in your distinction between subtitle lines and tracks. If there's no menu/navigational commands, the player will fall back to the flags of the PGS stream, YMMV.

Yes, I consider this IFO programming a part of the menu system, even though you can program it without click-actions on buttons.

Originally Posted by Chetwood

I'm not sure I understand what you mean. What in the specs makes you think that the manual selection of a track during playback should be overwritten by any flag of the container? When you start playback, the player selects the sub according to the flags of the container but the moment you cycle to another sub, only the selected one has to be displayed.

Matroska spec concerning forced track flag:

Set if that track MUST be active during playback.

It does not say, "must be active, unless the user chooses otherwise", but "MUST be active" - period - with a "MUST" in capital letters. This also seems to be the interpretation by Mosu, one of the main devs behind Matroska and the de-facto standard implementation.
The spec also has other things that are explicitly defined as to not be made accessible to the end user, like e.g. hidden chapters/editions.

That basically means that the "full" subtitle track would have to exclude the forced lines. Now, no one does that because 1. many players can only play one track at a time, 2. it is different from what peple find on their DVD/Blu-Ray sources and 3. they don't know about the spec anyways.

[Chetwood]

Originally Posted by sneaker_ger

Also, the option to only extract forced lines does not guarantee that the alien language lines are actually marked as forced, so you might end up with an empty "forced" track.

No, you're not. When a stream has been parsed entirely and no forced flags were found (which puts the blame on whoever did not author the disc properly), MakeMKV will remove the track from the MKV.

Originally Posted by sneaker_ger

It does not say, "must be active, unless the user chooses otherwise", but "MUST be active" - period - with a "MUST" in capital letters.

I think that's an overly strict interpretation. Gonna ask Mosu about this.

[sneaker_ger]

Originally Posted by Chetwood

No, you're not. When a stream has been parsed entirely and no forced flags were found (which puts the blame on whoever did not author the disc properly), MakeMKV will remove the track from the MKV.

Oh, I didn't know that makemkv does that automatically. But this is not a fault of the authoring house - the Blu-Ray spec does not dictate anyone to put forced lines into every track.

[ranpha]

Originally Posted by sneaker_ger

Let me get this straight: you are trying to proof your point by saying that players with menu support do correctly and automatically select the correct tracks/playlists? That's an argument supporting my stance - not yours.

No, what I want to say is that STBs can select audio/video language that the owner has set in the STB without fail. There is NO SUCH THING such as correct tracks/playlists when it comes to Blu-rays. In an unconfigured STB, the video player will always load the first movie edition, first audio track and no subtitles when a video is played. By configuring the STB to what the owner desire, the player can override the menu and straight to play the movie with the owner's audio/subtitle language preferences EVEN WITHOUT accessing the menu.

Originally Posted by sneaker_ger

Yes, because they do not parse the menus. Nev would've long since implemented correct automatic track/playlist selection for Blu-Ray if it would be possible without parsing the menus.

MPC-HC + LAV Splitter can already choose the correct track/subtitles language, as long as you configure LAV Splitter to do so. Only the playlist selection will still need work.

Originally Posted by sneaker_ger

No, that is not a flaw in the implementation. You rely on players behaving in a way that is not described in the specs. Then you call your non-spec-behavior "canon" and complain when it doesn't work.

No, it is the flaw in KMPlayer's subtitle renderer when it comes to OCD-ed DVD subtitles. Why is that then KMPlayer doesn't have any problems with playing multiple PGS subtitles at the same time? KMPlayer is spec-compliant, unlike MPC-HC is. KMPlayer will not have problems with the Case B if the user select track 5.

Originally Posted by sneaker_ger

It looks like this:

Come on man, please do not compare MakeMKV with an STB. MakeMKV will not know what those tracks are. Any decent STB knows exactly what those tracks are. And as pointed Chetwood, many of those checkboxes are created automatically by MakeMKV. Manual inspection is always a necessity for any BD rippers worth its salt.

Why closed-caption when I can use the regular subs just as well? I'm still not convinced that's the right term for any BD sub.

Because that's actually is the correct use for the closed-caption track for those situations.

[Mosu]

Originally Posted by Chetwood

I'm not sure I understand what you mean. What in the specs makes you think that the manual selection of a track during playback should be overwritten by any flag of the container? When you start playback, the player selects the sub according to the flags of the container but the moment you cycle to another sub, only the selected one has to be displayed.

You're assuming two things: 1. players can only ever display one subtitle track at a time and 2. we meant different things than what we actually did we we wrote the specs.

Citing the specs for "forced":

Set if that track MUST be active during playback. There can be many forced track for a kind (audio, video or subs), the player should select the one which language matches the user preference or the default + forced track. Overlay MAY happen between a forced and non-forced track of the same kind.

Two things to note here:

1. "must be active during playback". Not at the start of it, but during. The whole time.
2. The specs mention explicitly that a forced and a non-forced track of the same kind can be played at the same time.

Yes, our intention had indeed been that players would have to display more than just one subtitle track at the same time in certain situations.

[sneaker_ger]

Originally Posted by ranpha

No, what I want to say is that STBs can select audio/video language that the owner has set in the STB without fail. There is NO SUCH THING such as correct tracks/playlists when it comes to Blu-rays. In an unconfigured STB, the video player will always load the first movie edition, first audio track and no subtitles when a video is played. By configuring the STB to what the owner desire, the player can override the menu and straight to play the movie with the owner's audio/subtitle language preferences EVEN WITHOUT accessing the menu.

I'm not denying that a player could override the menu (though I haven't seen that done on an STB before myself). But this selection is a hit-and-miss operation. What I consider correct would be to play e.g. the Lord of the Rings on a player configured to English. The movie would then start with the English lossless audio track and only the Elbish subtitle lines. Now, there is no way without parsing the menu to correctly and reliably do that. The Elbish lines could be in the second English subtitle and not be marked as forced lines.

This is how people usually watch their Blu-Rays:
1. Put Blu-Ray in player
2. Wait till the menu has loaded
3. Press the "play" button of the menu
4. Enjoy the movie with the audio and the forced subtitles in your language.

The selection has been done by the menus in accordance to the player's preferences.

Originally Posted by ranpha

MPC-HC + LAV Splitter can already choose the correct track/subtitles language, as long as you configure LAV Splitter to do so.

No, it cannot. Let's pick up the example from above: the Elbish lines are in the second English subtitle and not marked as forced lines. You're screwed then, because LAV has no idea that it should play the second instead of the first English subtitle and it has no idea that the Elbish lines are not marked as forced. Each of these reasons alone would be enough to make LAV fail.

Originally Posted by ranpha

No, it is the flaw in KMPlayer's subtitle renderer when it comes to OCD-ed DVD subtitles. Why is that then KMPlayer doesn't have any problems with playing multiple PGS subtitles at the same time? KMPlayer is spec-compliant, unlike MPC-HC is. KMPlayer will not have problems with the Case B if the user select track 5.

Because I don't think displaying subtitles twice is non-spec-compliant. It is just your interpretation that it shouldn't, although it doesn't say that anywhere in the spec. You have been relying on your personal idea of a canon that does not exist.

Originally Posted by ranpha

Come on man, please do not compare MakeMKV with an STB. MakeMKV will not know what those tracks are. Any decent STB knows exactly what those tracks are. And as pointed Chetwood, many of those checkboxes are created automatically by MakeMKV. Manual inspection is always a necessity for any BD rippers worth its salt.

You brought up ripping, not I. Still, why do you think that sophisticated softwares like makemkv and LAV are not able to correctly detect and categorize the subtitles if it was so easy? The answer is: because it is not easy. Blu-Ray players don't need any subtitle categories and authoring houses do not need to categorize them. They just mux the streams together and then program a selection (partly automatic, partly through the graphical buttons of the menu) for the job. And of course the viewer can switch tracks freely (unless UOPs are in place) while viewing with the audio and subtitle buttons of the remote.

[nevcairiel]

Originally Posted by ranpha

Any decent STB knows exactly what those tracks are.

Actually, it has no clue what those tracks are. It relys on the BDMV or Java menu to let the user select the one he wants to play, the STB itself could not make any better choice as LAV or MakeMKV could.
Its all hidden in programmable logic, and extracing any track information from that is virtually impossible. It could make guesses on the main feature track, but not much more.

Regarding stream selection, the Blu-ray spec outlines how the player should select streams (if the menu doesn't overwrite), without checking i believe it was as simple as "first in the list which matches the wanted language". This may however be slightly weird for those tracks with dedicated forced subtitle lines, since the STB also can't distinguish between those without the menu.

[Chetwood]

Originally Posted by sneaker_ger

But this is not a fault of the authoring house - the Blu-Ray spec does not dictate anyone to put forced lines into every track.

Of course not. But it mandates flagging items as forced when the track is supposed to be forced, right?

Originally Posted by Mosu

You're assuming two things: 1. players can only ever display one subtitle track at a time

Because so far I haven't seen any that could display more.

Originally Posted by Mosu

2. The specs mention explicitly that a forced and a non-forced track of the same kind can be played at the same time.

Yes, our intention had indeed been that players would have to display more than just one subtitle track at the same time in certain situations.

Thanks for clearing that up, I stand corrected. Still, an odd choice, IMHO. I mean, what about a BD with one regular subtitle track, that has 10 or so items flagged as forced? Since the MKV container has to flag the entire track, the only way for me to watch with forced subs only, is to extract those items to a separate track. And if I don't remove the flagged items from the regular track, playing it, the player will show the forced items twice which might look weird?!

Given the specs I'm also quite astonished to see VLC not displaying sub tracks that are flagged as forced only.

[sneaker_ger]

Originally Posted by Chetwood

Of course not. But it mandates flagging items as forced when the track is supposed to be forced, right?

AFAIK: no. The concept of flagging lines as forced is a tool available to the authoring house, but they are free to not use it.

Originally Posted by Chetwood

Thanks for clearing that up, I stand corrected. Still, an odd choice, IMHO. I mean, what about a BD with one regular subtitle track, that has 10 or so items flagged as forced? Since the MKV container has to flag the entire track, the only way for me to watch with forced subs only, is to extract those items to a separate track. And if I don't remove the flagged items from the regular track, playing it, the player will show the forced items twice which might look weird?!

Yes, the situation is really unfortunate. You have the choice between ruining playback on most players and being spec-compliant and can't have both. In retrospect this was either a bad design decision of the Matroska team, lack of properly educating the users or the indifference of player devs.

Or maybe the spec could be extended to accommodate for this, i.e. lines that exist in both the forced and the user selected track should only be displayed once? idk...

[mindbomb]

Originally Posted by Chetwood

And if I don't remove the flagged items from the regular track, playing it, the player will show the forced items twice which might look weird?!

I don't think it would look weird. It would be identical pictures at identical positions. You shouldn't be able to tell that there were forced subtitles on... unless you chose a different language.

[Chetwood]

Originally Posted by sneaker_ger

AFAIK: no. The concept of flagging lines as forced is a tool available to the authoring house, but they are free to not use it.

I was referring to jdobb's comment:

Originally Posted by jdobbs

So in the end, there is only really only one truly forced subtitle method. The blu-ray standard spells out how forced subtitles work, not me. The standard says to set the flag.

Is there a link to the complete specs anywhere (no NDA required)?

[sneaker_ger]

Originally Posted by mindbomb

I don't think it would look weird. It would be identical pictures at identical positions. You shouldn't be able to tell that there were forced subtitles on... unless you chose a different language.

But who says they should have identical positions? The specs don't mention it and certain formats, like simple text (srt), don't have positional informations in the first place.

Originally Posted by Chetwood

I was referring to jdobb's comment

I don't know what to make of it. jdobbs seems to describe the meaning of "forced subs" in the context of the Blu-Ray spec. But it's not clear if the specs require anyone to actually use the method for alien languages. Both you and jdobbs recognize that this isn't the only method to do that.

Originally Posted by Chetwood

Is there a link to the complete specs anywhere (no NDA required)?

Unfortunately not. They are not publicly available.

[Chetwood]

Originally Posted by sneaker_ger

But who says they should have identical positions?

My example I made about having to remove the forced items from the regular track to stay spec compliant.

[TypX]

Originally Posted by Chetwood

Given the specs I'm also quite astonished to see VLC not displaying sub tracks that are flagged as forced only.

Because nobody ever bothered to tell us that it didn't work.

Anyway... fixed in 2.1

[mindbomb]

well, that is great news.

anyway, i've recently viewed Alexander Noe's version of the specifications, which can be viewed here: http://matroska.org/files/matroska.pdf

He says, "When several subtitle tracks are forced, the one matching the audio language should be chose."

so you could have multiple forced subtitle tracks? Isn't this different than what we were discussing?

[Chetwood]

Originally Posted by TypX

Because nobody ever bothered to tell us that it didn't work.

Probably because they didn't expect it to be solved any time soon, like this. I've always been annoyed by this bug too and was astonished to find a patch already existing for months that just isn't implemented.

[sneaker_ger]

Originally Posted by mindbomb

so you could have multiple forced subtitle tracks?

Yes.

Originally Posted by mindbomb

Isn't this different than what we were discussing?

I don't think we discussed what a player should do in the presence of multiple forced tracks, but only what it should do if a forced track exists and the user chooses to select a non-forced track.

[TypX]

Originally Posted by Chetwood

Probably because they didn't expect it to be solved any time soon, like this. I've always been annoyed by this bug too and was astonished to find a patch already existing for months that just isn't implemented.

If the patch hasn't been integrated, then it most likely doesn't work or work as expected.
Some bug are hard to fix, some are not, some just need people with time to fix them. But in any case to fix them we need to know about them. So please report bugs.

Originally Posted by sneaker_ger

I don't think we discussed what a player should do in the presence of multiple forced tracks, but only what it should do if a forced track exists and the user chooses to select a non-forced track.

I agree, a player shouldn't and surely won't bypass user preferences because the people that made the file wanted it.
Not to mention that players aren't really designed to play multiple tracks of same type at the same time.