[vlc-devel] Re: [PATCH] USF subtitles enhancements

Bernie Purcell b.purcell at adbglobal.com
Thu May 24 01:35:24 CEST 2007

On Wed, 2007-05-23 at 17:26 +0200, Steve Lhomme wrote:
> Bernie Purcell wrote:
> > This patch brings the USF subtitle support more in line with the spec by
> > adding support for additional features. It is still not complete, but
> > the patch was quite big enough already at this point. :-/
> > It does the following:
> > * Add a control method to mkv.cpp to allow retrieval of attachments
> > within the MKV container.
> > * Add a shortname to sdl_image so we can do a module_Exists() on it
> > * Add support for <image> tags in the subtitles to display graphical
> > images embedded as attachments as part of the subtitles
> > * Add support for multiple text / image regions within the one sub
> > picture plane - all with different alignments
> > * Allow style information to be overridden by explicit alignment tags
> > * Make USF styles relative to Default, as per spec, and allow font sizes
> > to be relatively changed by + and - in the attribute
> > * Patches to vout_subpictures.c to allow for regions within the
> > subpicture to have different alignments to one another, and minor
> > patches to everything else that tried to setup subpicture alignment, so
> > that it now sets this up on the subpicture_region instead.
> > * Extensive changes to freetype.c to correct a problem with styled
> > bi-directional text not being implemented correctly the first time
> > round.
> >
> > I am aware of a problem that is occurring at the moment, when the video
> > area is resized to be less than 1:1 - everything swaps to a centre
> > alignment (see sample mkv file). I haven't managed to work the cause
> > yet, but as it is getting difficult to continue working on a monolithic
> > patch this size with other contributions impacting it I thought I'd
> > submit now before anything else changes. Perhaps some of it at least
> > could be committed and alleviate this issue?
> > The attached mkv showcase the new features added. Not all the features
> > requested by the file are implemented, but it's another step towards
> > full compliance.
> >
> > Bernie
> >   
> I think there might be a problem with attachment_t being a class and not 
> a struct. Since it's used in vlc_demux it might be used in other 
> containers too (M4A can have images for example).
> I can only comment on the MKV part, dunno about the rest.
There's actually a struct, which is exposed in the standard includes,
and a class which is used internally (more to try to be the same as all
the other existing functions in the code than anything else). The
control message copies the fields from the class to the struct in order
to provide it to other modules, which are usually written in C.
> Steve

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