[theora] Choosing subtitle language

[Hakon G]

I am wondering how negotiating about text subtitles is supposed to work in Theora?

(1) Will it be like the server first transmit a list of available languages, and then it's up to the client to possibly pick a language, either automatically or by user interaction, and then ask the server for that particular subtitle stream?

(2) Or will all subtitle streams be sent simultaneously and regardless, thus fully leaving the decision to the client? That would be a waste of bandwidth though.

(3) Or will the client send a list of prefered languages, similar to the http_accept_languages header? And then the server tries from that list and sees what it can possible provide?

I'd say the fist option is better. of course, it should be possible to switch subtitle track anytime though.

I'm also thinking about such a thing as a combination of the same audio language and subtitle language would be wished for by a few users, whereas most of them would not want the subtitles in that case.
For example, English speaking users would probably want English subtitles when the audio is Spanish, bot not when audio is English.
That could easilly be handled on client side if option #1 or #2 is chosen, provided that there is also a valid audio_language coment provided.

One problem though, would be how to behave in e.g. newscasts, where there may be different spoken languages as  the clip rolls.
I'm not sure if the LANGUAGE comment for audio could be changed as the stream is running. Nevertheless, it would probably be too much to ask, expecting content providers to bother and dynamically set such flags throughout a clip.

Perhaps this issue can't easilly be solved.
Anyway, it would be imporant that the subtitles feature is promoted good, otherwise content providers would stick to the conventional methods, and just include all subtitles as part of the video image. Which is a shame when there is such good interactive possibilities coming with digital television.

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Hakon

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