[ogg-dev] liboggplay and overlay video

ogg.k.ogg.k at googlemail.com ogg.k.ogg.k at googlemail.com
Mon Aug 18 02:51:48 PDT 2008


I've eventually released the first version of my rendering library for
Kate streams,
and I've recently been hacking away at adding it to liboggplay. That was the
missing "overlay" mode to the browser_plugin patch I sent a while ago.

Now, I'm not too sure how to expose those overlays to liboggplay users: the
obvious solution is to add a RGBA video type, and expose the render of this,
which the client can then overlay onto the video. I've done that, and it works
(modulo bugs). However, it's slow, both because of the two renders (once to
render the overlay in liboggplay, the second to overlay it onto the video in the
client code), and because libtiger (my rendering lib) only draws what's needed,
whereas liboggplay exposes a full size buffer (would need at least a bounding

Another solution would be to let liboggplay overlay Kate tracks onto the video
directly - but this would seem contrary to the design, where each track feeds
data to the client. Here, a track would pipe its data onto another track's data.

I suppose I'm asking for input on whether this would be OK, or if someone can
think of another better way.

For the interested, here's a Theora render of libtiger rendering the demo.kate
stream from the libkate distribution:


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