[MPlayer-dev-eng] [PATCH] libass - fix text aspect w/ panscan and vo_gl

[Jindrich Makovicka]

On 10/10/07, Evgeniy Stepanov <eugeni.stepanov at gmail.com> wrote:
> On Saturday 06 October 2007 21:41:27 Jindrich Makovicka wrote:
> > On Sun, 30 Sep 2007 21:23:44 +0400
> >
> > Evgeniy Stepanov <eugeni.stepanov at gmail.com> wrote:
> > > This patch does not change logical to screen coordinates mapping.
> > > This way, for instance, a subtitle with \pos(0, 0) will always be
> > > placed at the left-top corner. This is wrong, subtitles placement
> > > (relative to the video) should not change with panscan, even if they
> > > will sometimes move outside the screen.
> >
> > This one should handle \pos and \move correctly.
>
> Sorry for the delay, I'm quite busy lately.
>
> With the latest patch positioned subs are sometimes cropped and sometimes not,
> and everything else (top and bottom subtitles) is never cropped (they occupy
> more lines instead). I don't think we should handle positioned subtitles
> differently here.

Can you provide a sample where the positioned titles aren't cropped?

> There is probably some misunderstanding. To me, the correct behavior is the
> one observed with vf_ass + vo_xv. Subtitles are never deformed or moved
> relative to the original video frame. Exactly like if they were encoded into
> the movie (hardsubbed). If you scale it up too much, parts of them will go
> outside the screen and will be cropped.

I dont't want to provoke another bikeshed, but this can be matter of
personal preference. I prefer that the top/bottom titles are always
fully readable and/or can utilize the black bars under the video. I
also use a custom subtitle scaling because I find most of the SSA/ASS
subtitles too small anyway, so I don't care much about subtitle
positioning precision, although I understand that the explicitly
positioned titles should stay in their place because they can relate
to the video content.

> Implementing the same with vo_gl is very simple. I didn't do much testing, but
> it seems there is nothing in the code that could not handle negative margin
> sizes. Therefore, we could have vo_gl pass exact margin sizes (like in the
> first part of your patch), negative when the image is cropped. No changes to
> libass are required.
>
> What do you think of this idea ?

See above. This is exactly what I would like to avoid, because it
defeats the advantage of vo_gl which can display the subs in the black
bars :)

Could we make this behavior tunable by some option, like 1) fixed
position for all (your way), or 2) fixed for \pos and \move, keep
others on screen (my preference), or 3) keep everything on screen?

-- 
Jindrich Makovicka