[ogg-dev] Ogg/Kate preliminary documentation

ogg.k.ogg.k@googlemail.com
Thu, 07 Feb 2008 05:29:45 -0000

Hi,

I recognize the main name behind CMML here :)

Does the redesigning of CMML allow overlapping clips ?
This is the main reason of my current ramblings about seeking.

While karaoke was one of the initial goals behind kate, it is just
a way the format can be used with (in fact, the format itself does
not refer to karaoke at all, but styles and motions).
At the moment, it is a fairly versatile text based presentation/video
composition that can be superimposed onto a video (or not).
This includes overlapping events, and animations, which I think
CMML doesn't do (and which I didn't see it do, due to it being
metadata about other data, and thus not "changing" in itself). But
it seems to be changing goals, based on docs Conrad sent me
links to.

About requirements from Ogg itself, I don't think there is anything
really - I've just listened to Ralph's talk about seeking in Ogg, and
what I'm getting from it is "well, though, a multiple seek is
required",
so that's just the way it is. Otherwise, everything sits just fine within
Ogg.

You're quite right about CSS too. It's awfully complicated (but then
I originally thought the same about CMML including HTML bits),
and I made a simpler (and of course much less versatile) style setup.
I wonder if this is a mistake.

I didn't know you could time CSS changes however, unless you just
refer to replacing the text by another text with the same actual visible
string but css markers placed differently ?

Anyway, seeking is the only bit that's really left now, it all works fine
(from the encoder/decoder lib point of view anyway), and I didn't hit
any showstoppers from ogg, hence no extra requirements. What did
you have in mind when you referred to those issues that came up when
you designed CMML ?

As a bit of background, so you understand what I'm talking about, one
of the things I can do with kate is to have (eg):
- a (TV station ?) logo in a corner
- a scrolling transcript of what is being said
- a digital time in another corner
- a channel number in a third
- and whatever else you'd need
all at the same time on screen, optionally moving around.

It's not really showable now because you need a patched version of xine
to actually view a video with the kate bitstream rendered on top of it, but
you get the idea.
Unless the changes to CMML are geared towards allowing this kind of
things too ?

Thanks