MPEG-4/3GPP Timed Text Subtitles?

[Teetrinker]

..., but seeing how Apple actually have been part of founding the mp4 container, and that they're quite ahead in the MPEG-4 support, I'd say that their word is to count on.

I wouldn't say that apple is ahead in the MPEG-4 support. I would say their MPEG-4 support is poor. The Quick Time Player is one of the worst players for mp4 files, IMO. But the player is honest, if it comes to mp4 content that he doesn't support.

Dependent from the MPEG-4 part, I would trust other people more than apple.

Apples player is like the most players around, more or less, a mov player. But that is my opinion and I am have a favor for MPEG-4 Systems.

Back to the SUBs, I would prefere subtitle realized through a BIFS animation stream. The animation stream would be more flexible if you want to use effects. The text in the animation stream don't have to be real text, it could be a vector graphic.
But for compatibility reason I would use timed text. It is more likely that this will supported by more players.

[Elias]

..., but seeing how Apple actually have been part of founding the mp4 container, and that they're quite ahead in the MPEG-4 support, I'd say that their word is to count on.

I wouldn't say that apple is ahead in the MPEG-4 support. I would say their MPEG-4 support is poor. The Quick Time Player is one of the worst players for mp4 files, IMO. But the player is honest, if it comes to mp4 content that he doesn't support.

Dependent from the MPEG-4 part, I would trust other people more than apple.

Apples player is like the most players around, more or less, a mov player. But that is my opinion and I am have a favor for MPEG-4 Systems.

I know that Apple's MPEG-4 support sucks. Hell, their MPEG-4 Part 2 doesn't even support Advanced Simple Profile. I was comparing them more with DivX, and even though DivX gives better encoding quality, and supports more advanced features like B-Frames/GMC/QPel etc, let's face it: DivX doesn't follow the MPEG-4 standard very well at all; they've pretty much concocted up their own standard. The QT Player sucks a lot (it has some nifty editing features though), but my take on it is that if an mp4 file works in QT, it generally works everywhere else. But yeah, back to the subs.

[The DJ]

Should be working now btw in the development tree (since today)

[Elias]

Should be working now btw in the development tree (since today)

Awesome! Care to give any link to the latest development tree that can handle it?

Edit: I tried it out now, and it does work. However, there are still some minor issues that need to be worked on.

1. Wrong fourcc is being displayed in the stream and media info window. It should be tx3g and not subt.
2. MPEG-4/3GPP Timed Text is only encoded in either UTF-8 or UTF-16. Apparently, the latest VLC trunk cannot handle displaying characters like å ä ö since they're b0rked here when I tried it with the sample.

[Teetrinker]

2. MPEG-4/3GPP Timed Text is only encoded in either UTF-8 or UTF-16. Apparently, the latest VLC trunk cannot handle displaying characters like å ä ö since they're b0rked here when I tried it with the sample.

At SUSE 9.2 I have no problems with special characters. The subtitle coding is set to "System Default" (somewhere hidden in the VLC settings), and the system use UTF-8 .

[Elias]

2. MPEG-4/3GPP Timed Text is only encoded in either UTF-8 or UTF-16. Apparently, the latest VLC trunk cannot handle displaying characters like å ä ö since they're b0rked here when I tried it with the sample.

At SUSE 9.2 I have no problems with special characters. The subtitle coding is set to "System Default" (somewhere hidden in the VLC settings), and the system use UTF-8 .

That seems to be the case for you. I have it on ISO 8859-1, and most Windows users do. However, MPEG-4 Subtitles should be decoded as UTF-8 or UTF-16 by default (depending on what they were encoded with), because that's what the subtitles are encoded in. Here in Windows, it's not working with those non-latin letters (not for me at least).

Edit: I just switched to UTF-8 in the VLC settings, and the non-latin letters work now. An auto-detect MPEG-4 text encoding for VLC would rule, because you never know what people living in Japan use for text encoding on their operating systems, and besides, UTF-8 is a nice Unicode standard

By the way: thanks a lot for this update! It was really the only thing I found missing with VLC

[bond]

Should be working now btw in the development tree (since today)

great stuff, thx a lot!

i have some questions:
- does vlc support any of the more advanced features, like color, font, italic aso...? you can find a list of what all is possible here
- does vlc support timed text in .3gp? i have the 3gpp timed text reference sample and vlc doesnt display any text in them
- does vlc take things like subtitle positioning into account?
- is the timed text creation code of vlc fixed now too? i tried the following cmdl on a .mkv and .ogm with a srt subtitle stream but the output .mp4 doesnt have a timed text stream (with old versions of vlc it worked):

Code: Select all

vlc input.mkv :sub-track=0 :sout=output.mp4

[Elias]

does vlc take things like subtitle positioning into account?

Yes:

settings>preferences>input/codecs>other codecs>subtitles>subtitles justification> change position to your preferable position.

[bond]

does vlc take things like subtitle positioning into account?

Yes:

settings>preferences>input/codecs>other codecs>subtitles>subtitles justification> change position to your preferable position.

no, i meant the positioning of the subs stored in .mp4 (yeah when creating a timed text stream in mp4 you can define where it should be displayed)

[Elias]

no, i meant the positioning of the subs stored in .mp4 (yeah when creating a timed text stream in mp4 you can define where it should be displayed)

I knew that I just thought that you meant when watching.

[Scorp1us]

...,

Back to the SUBs, I would prefere subtitle realized through a BIFS animation stream. The animation stream would be more flexible if you want to use effects. The text in the animation stream don't have to be real text, it could be a vector graphic.
But for compatibility reason I would use timed text. It is more likely that this will supported by more players.

If I was not concerned about compatibilty, how would I go about adding in vector graphics? I'd like to do a Madded-like annotation in my video that can be turned on or off.

[Elias]

Just for the record, I did not write that.

[The DJ]

- no vlc does not support any of the advanced option
- no vlc does not support writing Timed Text
- yes vlc should theoretically support timed text in 3gpp if it uses the same atom
- positioning IS one of the advanced options of Timed Text and vlc doesn't support this for ANY of the subtitle formats that it supports.

If you want this, you are welcome to implement it.

(Or pay me ridiculously much to do it for you )

[Elias]

Well, I just want to say thanks for implementing this neat feature in VLC

[bond]

The DJ, there seems to be a small problem described here:
http://forum.doom9.org/showthread.php?t=104251

[Teetrinker]

The DJ, there seems to be a small problem described here:
http://forum.doom9.org/showthread.php?t=104251

Any news about the problem mentioned by bond? somebody took a look at it?

[The DJ]

Basically it's a dirty trick/hole in the specification of Timed Text.

The behaviour of empty subtitles is not specified. We do not draw subs in ephemer mode (when a new one appears the old ones disappear). However most clients seem to use this, and then use empty subs to mark the "end time" of a previous subtitle.

This cannot have been the intent of a specification as advanced as the Timed Text spec. I refuse to implement this retarded and KB wasting method. Subs should have end times.

If someone else wants to implement, that's fine, but i'm not doing it.

[Teetrinker]

Thanks for the answer.

They way this is done in ISO/IEC  14496-17, looks to me very MPEG 4 alike. If you have a scene(BIFS), with some node, the node will shown until you remove it.

In ISO/IEC 14496-17 you can find this text:

An empty text sample, that is a text sample without data (hence without a text string and modifiers), may be used to terminate the display of a text string prior to the start of the display of the next text sample in the stream. Such empty text sample shall be carried in a TTU[1] as a separate access unit.

So it seems that the use of empty text sample is defined by the standard.

[The DJ]

Mmm, this was not part of the original 3GPP specifications that i have. Apparently they changed some things.

I still think it's a stupid design mistake......
It's a bit busy atm, i'm not sure if and when i'll get around to it.

DJ

[TonyC]

This is the single issue holding me back from using VLC to play mp4 files with Timed Text subtitles, something I and the company I work for are looking into for the future.

Are there any updates on this issue? It,s pretty important to us.

[TonyC]

Please, any info on when this is planned to be fixed? I think correctly working subtitles is quite an important issue.