MPEG-4/3GPP Timed Text Subtitles?

[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.