[vlc-devel] Re: Adjusting VCD subtitle offsets

R. Bernstein rocky at panix.com
Sat Jan 8 18:41:56 CET 2005

Gildas Bazin writes:
 > I would prefer a global option (which is why the code was dropped during the 
 > port). 

So considerate of you to mention after the fact. ;-) Before dropping
the code it would have been nice if you had said something, like I
just asked. Or even afterwards such as in a CVS commit. 

There seems to be a habit seems to be to wait for someone to notice
breakage and ask to find out what others have been thinking. I don't
know how other developers feel, but learning the views and intentions
after the fact and after breakage, lessens my enthusiasm for working
on vlc. 

This is partly why I've been slow to pay attention (let alone fix) the
CD-DA, VCD, or SVCD/CVD subtitle breakage. Another part is the lack of
any sort of formal documentation on the major upheaval that have gone
on. (Don't get me wrong, I think overall they are good and needed -
just very heavy handed.)

 > There is actually already an option that does part of that 
 > (--spumargin) so it might be worth basing your code on that.

So what are your thoughts on why you this wasn't used when you ported?

The name spumargin is I think a little weird. SPU is jargon and
somewhat DVD (or is it MPEG?) -ish. Just parsing the name is weird. Is
SPU what is generally used to refer to subtitle? Wouldn't
"subtitle-margin" or, if this is too long, "submargin" be clearer?

Would a die-hard VLC developer just go change this option everywhere,
probably miss a couple of spots and wait for people to notice? 

Perhaps some of this discussion goes on in IRC. But if it does none of
this great ideas and decisions seems to make it either to vlc-devel or
any sort of developer documentation.

I've heard the explanation that all you gotta do is ask, and maybe
someone at sometime if they feel like it will answer. The thing about
having documentation is the answers can get better, more detailed,
more accurate over time. People can build on the explanations of
others. Neither IRC discussions nor vlc-devel posting really are
suited for this.

 > As for the aspect-ratio this should be relatively easy to fix since the 
 > subpicture core supports rescaling, I'll have a look at it.

Last I looked, the aspect ratio is set 1:1 which, according to my
understanding, is correct. So either the code handling the scaling is
faulty or hooks in at the wrong place. The expedient (ugly) approach
is to *reverse* scale. So a the usual 4:3 aspect ratio would mean
scaling the subtitle by 3:4. Somewhere in the old code I think I had a
way to get the aspect ratio. And idea behind the code on line
442 which I think is hoaky

    p_subpicture->i_x *=  3 / 4; /* FIXME: use aspect ratio for x? */

makes use of this.

Finally, has does anyone know what's with the transparency the in new
rendering system? Is there it there but just somehow not making it for
CVD/SVCD?  (The old code in fact did have some handling of CVD/SVCD

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