[MPlayer-dev-eng] [PATCH] demux lavf: Print rotate information as identify msg

[Xidorn Quan]

On Fri, Nov 16, 2012 at 2:10 PM, Reimar Döffinger
<Reimar.Doeffinger at gmx.de>wrote:

>
>
> On 16 Nov 2012, at 02:37, Xidorn Quan <quanxunzhen at gmail.com> wrote:
>
> > Hi,
> >
> > This patch print rotate information in metadata of mov file as
> > identify message with tag "ID_VID_<vid>_ROTATE" to enable frontends
> > to rotate the video themselves. I'm not sure if adding such output
> > will break something, so I sent this patch here. Please comment.
> >
> > I tried to make mplayer automatically rotate video according to this
> > information by inserting vf like vf_ass, but I found that vf_rotate
> > is too tricky to be used here: it can only rotate 90 and 270, but
> > the angle may be 90, 180, or 270. I don't have any idea of the right
> > way to implement this feature. Any suggestion?
>
> 180 degree is done via flip flag, which does not need any software
> processing.
>

180 degree rotation is not the same as flipping. Flipping just make
images upside-down. vf_flip + vf_mirror or vf_rotate * 2 are two
feasible method to implement 180 degree rotation.


> vo gl and some others could also support arbitrary rotation via hardware,
> so it might be interesting to also later add a VFCTRL like for ass to avoid
> software processing where unnecessary.


Sounds good.