Introducing Ogg Kate, the next generation subtitle format

In a time when free formats are finally gaining some terrain over their counterparts, there was a niche in Ogg that had not been properly tapped yet: captioning.

Well, sure, those who have been paying attention to the last few years may have heard of attempts like CMML or the vaporware Writ. You might even have heard of the SRT mapping. But I would say that none of them cover today’s needs when it comes to a simple format that does subtitles, lyrics and even Karaoke with all the neat stuff subbers — or caption authors, if you will — expect; from basic text to complex animations; from simples notes in English to entire books in Sanskrit or Chinese. To paraphrase the cliché, it’s only limited by your imagination, and even that I’m unsure of as the format is extendable.

But in an article where we introduce Kate it wouldn’t make sense to just stop there, would it? Sure, Unicode is good. Sure, extensibility with backward- and forward-compatibility is good, but what about the REALLY neat features? Mayhap streamability? MPEG-4 Part 17 has that and nobody uses it for that feature alone. A simple syntax, then? Certainly. Not having one was what killed USF.

Hm, you want more? Why, such a demanding audience we have today. Well, imagine this: you downloaded a large film in a foreign language — say, Korean — and Kate subtitles are available in your language, but turns out those aren’t complete yet. Fast-forward some days and, what you know, there’s been an update! Finally you can watch the whole thing — it just sucks that you’ll have to download the entire file again. Right? Nah. Just get the Kate script and use an application to merge it with the film you already have. You can go as far as leave the two versions in to compare them while playing. And in an age of wiki collaboration, what stops you and your friends from botching improving the script?

But let’s leave the snarkiness aside for a bit. If you want a free format for captioning you’ll find Kate good enough for all your needs, and with Ogg’s multiplexing you can in one file add a simple transcript of a Speex track, which you had there in the first place for the blind, then add a translation caption of the original dialog (for the people who don’t speak French or Japanese or whatever) and finally add a copy of that one but with pretty colors and animations for those who would rather have that.

“Ah”, but you say, “there’s a catch somewhere, innit? I’m pretty sure no applications work with Kate.”

I’d say it’s a fair point, but considering Kate just started this year, we already have playback support in VLC and Cortado, with output available from vorbis-tools and ffmpeg2theora, plus a bunch of patches to more software than you can count with your two hands just waiting for the developers to commit them, I think we have a solid base here.

The future looks bright. Help us make it so.

Oh, and happy new year!

6 Responses to “Introducing Ogg Kate, the next generation subtitle format”

  1. 1 rm

    An unfortunate choice of name, considering that Kate is a well-known KDE text editor (

  2. 2 Lex

    lol, agreed rm. although, I thought that this had something to do with Quanta+/KDE WebDev team as well as the KDE advanced text editor.

    I’ve been using Matroska *.mvs for subtitles, so it’s good to see OGG get this too.

  3. 3 Pham

    Can this allow DVD subtitles ?
    Unicode does good. But DVD using images, and not text, so Unicode
    can not be used.
    Kate has images ?
    Theora is great, but no subtitles means English movies are nogo for foreigners.

  4. 4 Ivo

    Pham, there is a patch for Thoggen waiting for approval. Ogg Kate cannot be used directly in DVD video, since that media uses an MPEG-specific subtitle format, but you can convert from Kate to DVD subtitles.

  5. 5 Giom

    In order to gain acceptance, Kate needs to work its way into other projects such as Subtitle Editor, Gnome Subtitles, KSubtile, Gaupol, Perl libs ( and even Media Subtitler) - besides the playback software.
    This is important for popular creation and conversion.

  1. 1 Boycott Novell » Links 02/01/2009:

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