Forced Subs

[Kez]

I've also been wrestling with getting forced subtitles to work properly for some time on both DVD and BD. Looking at all the posts in the forums about forced subs, it seems it's not all that straight forward.

Below is my current understanding of how forced subs work. It'd be great if others more knowledgeable than me could add to this, fill in any gaps, and correct any errors.

Maybe the end result could become a sticky or tutorial for handling forced subs?

Any help in sorting out the different scenarios and the appropriate steps to take for each one when copying or ripping to a file format for DVD and BD is greatly appreciated.

Thanks!

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From my experiences with several different movies there seem to be a number of different scenarios:

Case 1
The forced subs are rendered directly onto the video frames on the disc. Ripping without selecting any subtitle streams still allows the forced subs to display as they are part of the video itself. This is probably the least common case. I've only seen it with older DVDs.

Case 2
The forced subtitles are contained in a completely separate subtitle stream on the disc (i.e. the stream contains ONLY the forced subtitles).

The forced only subtitle stream should be displayed by default, but for some reason this only seems to be the case when you copy the disc with menus intact. When copying without the menus (e.g. main movie only) it seems that the forced only subtitle stream can no longer be properly identified by players.

When copying without menus, to get the forced subs to always display, check the box for the appropriate subtitle stream and also make it the default stream by turning on the blue arrow indicator.

If ripping to a file format (e.g. mkv, mp4, mpg), the forced subs stream can then either be:
a) rendered to the video so forced subs always show. However do not select 'display only forced subs' in this case as the subtitles in the stream are not 'marked' as forced (though possibly the stream itself is??), or
b) extracted to a file, in which case depending on how you set up your player the external forced subs file can display by default, or may need to be selected to display the forced subs, or
c) the subtitle file can be muxed into the container and set as the default stream (e.g. mkv).

I'm not sure if there is a way for DVDFab to determine which subtitle stream contains only the forced subs so it can be automatically selected and also made the default.
- Maybe the stream is 'marked' in some way to indicate it is the forced subs stream? (Is this how hardware players identify a separate forced sub stream?)
- Or would it be possible to compare it in size to the other subtitle streams and make a determination that way? I figure the forced sub stream would be considerably smaller than any full subtitle stream in the vast majority of cases.

Case 3
The forced subtitles are part of a full subtitle stream, but are specially marked as forced within the stream so that a player can detect them as forced and will then always display them.

When ripping it is necessary to select the stream in which the forced subtitles are appropriately marked as forced. Do not mark the stream as the default subtitle stream (blue arrow) when copying the disc, else all subtitles in the stream will display, not just the forced ones. Players should detect the subs marked as forced and display them without the stream needing to be specifically selected.

As above, when ripping to a file format the forced subtitles within the full subtitle stream can be:
a) rendered to the video directly. In this case DO check 'display only forced subs' as the subs in the stream are marked as forced.
b) extracted to a file
c) subtitle file muxed into container.


If you have already copied discs where the forced subs don't display correctly, you can usually correct the situation using an editor as long as you have copied the subtitle streams needed. Precisely for this reason I usually copy all the subtitle streams for my language (English).

I then use IFOEdit to add a (SetSTN) Set Subpicture Stream Nr pre-command to the PGC Command Table for the stream I want to be the default. If it is a forced subs only stream, I then set the ON/OFF value in IFOEdit for the pre-command to ON (display all subs). If it is a full subs stream with forced subs appropriately marked, I set the ON/OFF value in IFOEdit to OFF (display only the forced subs).

There are other editors that may be easier to use than IFOEdit, but I'm not familiar with them.


Thanks,
Kez

[90312]

So far I've selected all english subtitles, when more that one is present, and turn them off with the player's remote and the forced go ahead and display. I hope this holds up cause it is easy.

[signals]

There are indeed many different ways to display subtitles. The ones we are talking about here I refer to as translation subs, since this is the most common use for them (supplying translated dialog that is not spoken in the native language of the Region or country for which the disc is intended).

Case 1 in post#1 is not really a forced sub since it is optically or digitally printed into the film and encoded along with and as part of the video. There is no subpicture stream for it and nothing to manipulate.

Case 2 may or may not be true forced subs either, it is (in most cases) defaulted to display by the menu system or the default arrow in DVDFab re-author modes (Main Movie, Merge and in some cases, Customize). An example of this technique is the title Apocalypto, at least the R1 version.
On older discs and a few current ones, the forced subs are contained in a standalone stream like this, so be careful with the Ripper settings for "Display only forced.." since default-play streams will not display if you check the box.

Case 3 are true forced start subs, examples of this technique are DaVinci Code and many others. If they are included when the original disc is processed, they will display automatically even if the menus are not included.

You can quickly test a DVD for forced subs, and change them from forced to normal or normal to forced using the free DVDSubEdit, a great tool that operates on the sub streams within the VOB files. It also lets you change colors, position and timing for any individual subpicture or the entire stream.

[Deklin]

How do you turn on the blue arrow indicator when ripping a BluRay? There is no area next to the 'subpicture' checkbox on the bottom to add a blue arrow. It appears on the top part where my Audio selection occurs, but only if I do mkv.remux otherwise I do mkv.h264.ac3 which only gives me a single selection option for audio. What i'm trying to do is rip my BD to burn in the forced subtitles but still allow me to enable full subtitles when needed.

[IPopov50]

@Deklin
"blue arrow" you are referring to is a "default" designator. Otherwise, stream with "blue arrow" next to it is a default stream. Naturally, you would need at least two streams, one of which could be designated as default.
mkv.remux profile supports multiple streams and you have a choice for "default stream".

What i'm trying to do is rip my BD to burn in the forced subtitles but still allow me to enable full subtitles when needed

what you need to do is select desired subtitles stream and do not check "forced subtitles only" box. As a result you will have subtitles stream that either extracted as separate file(s) or rendered in and become part of the picture (you can't turn them off). If you want to have option to turn subs on and off, you have to choose to extract subs and re-mux them back using different software, e.g. mkvmuxer.