[MPlayer-dev-eng] [PATCH] Add support for rotating the video via OpenGL.

[Reimar Döffinger]

On Thu, May 09, 2013 at 08:27:22AM -0400, compn wrote:
> On Thu,  9 May 2013 08:59:09 +0200, Reimar Döffinger wrote:
> >My thinking was that this probably could be implemented by some of the
> >other vos, too, so I thought it make sense like this.
> 
> i think it makes sense. we have -flip and -vf flip.

We need flip for video formats that are upside-down.

> >But I don't mind changing it if you think it is better as something
> >gl specific.
> 
> do you think other vo's can handle rotating osd as well?
> -flip does not flip osd. maybe we should make a note of that in the
> manual. is -flip done in vo or decoder? i mean is it faster/slower
> than -rotate ? would it make sense to make flip an alias of -rotate 2 ?

Flip only changes the stride. For gl it's the same basically as
rotate 2, but as you said it does not affect the OSD.
Maybe this needs more thought, but currently -flip is meant
for correcting upside-down videos, whereas -rotate is meant
for rotated displays.
-vf rotate can be used for either, depending on where you place
it relative to the osd filters, however if you want gl's
high-resolution OSD/subtitles you can't use the rotate filter
to have them rotated...
Maybe it would make sense to have separate flags for OSD
and video rotation.

> >+.B \-rotate <0-3> (experimental)
> >+Rotate display by 90, 180 or 270 degrees.
> 
> how about
> +Rotate display by 0 (0), 90 (1), 180 (2) or 270 (3) degrees.
> 
> i remember long ago trying to put -vf rotate=270 ... and having it work
> based on some bug or other.
> 
> i ust like to make things complicated. :P

Well, there is an argument for marking the rotation in degrees,
especially since -vo gl could support it without too much effort.
I was just wondering what to do if certain values are unsupported.
It also would no longer match -vf rotate then.