[gst-devel] DVD Navigation progress
thaytan at mad.scientist.com
Thu Jan 22 16:58:01 CET 2004
<quote who="Ronald Bultje">
> On Tue, 2004-01-20 at 14:22, Jan Schmidt wrote:
> > * It may use wrong colours in the menu or break in other ways.
> > - This is because the mpeg2subt element relies on knowing colour
> > tables etc, which are usually sent by libdvdnav before the mpegdemuxer
> > creates the subtitle_stream_1 pad and it connects to mpeg2subt - so
> > mpeg2subt never finds out about it.
> Colour tables should be sent as init data in the GstCaps on negotiation.
> The same needs to be done for STSS data in quicktime (MPEG-4 AAC),
> WMAv1/2 audioheader extradata in asf and Vorbis-headers in Matroska.
I considered this. The problem is that the colour tables change through the
lifetime of the stream, which would mean renegotiating the caps. That would
work, it just feels messy :-
I consider the lookup table more like data that should be arriving in sequence
in the subtitle stream. The problem is that mpeg doesn't do it that way, so
dvdnav has to 'insert' an extra piece of information into the data flow.
The only mechanism for doing this in GStreamer at the moment is the Navigation
events - although I'd be happier if it weren't called that for this use case.
The solution I have in mind at the moment is to have mpegdemux cache the
subtitle colour table and issue it to any subtitle pad when it is linked -
by sending a copy of the event onward rather than via caps.
Jan Schmidt thaytan at mad.scientist.com
<stibbons> Yeah. The whole climax thing would make much more sense
if I'd paid attention.
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