[vlc-devel] Dynamic rendering for Kate streams

ogg.k.ogg.k at googlemail.com ogg.k.ogg.k at googlemail.com
Thu Nov 13 13:52:33 CET 2008


I have rendering working using an external lib (see attached patch for
However, I can't find a good way to get notified when preferences get changed
in order to reconfigure the renderer. Either the callback is set in
the add_integer
and friends lines, and we don't get a pointer to the decoder in the
callback (there
could be multiple ones), or we create the vars using var_Create and friends plus
var_AddCallback, in which case the callback doesn't get called (I
think the var is
just a copy, and thus useless for this purpose). Any idea how to get this ?

Also, I've looked at the libass code Fenrir pointed to, and I don't
see what's the
use of the pf_re_render function: it's called just before pf_update_regions, and
the test for the final_spu buffer puzzles me. It should not be needed,
what is the
purpose of this ?

Last, rendering doesn't look as good as it does in GStreamer as I have
to draw to
a SPU that then gets merged onto a subsampled YUV video. This means chroma
bleeding. Pure green text looks not very nice, though white looks good. Fiddling
with the blend.c function that gets used, I managed to get rid of that
bleeding, but
at the cost of other artifacts, and it doesn't look better all in all,
so I'll leave it as
is unless there's a known trick to get colored rendering looking better.

See attached patch for info. It's ready to go, but I thought I
wouldn't send it as a
[PATCH] yet, pending these niggles.

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