[MPlayer-dev-eng] [PATCH] Fix offsetting in Theora video files

[Giorgio]

2010/3/16 Reimar Döffinger <Reimar.Doeffinger at gmx.de>:
> On Tue, Mar 16, 2010 at 01:33:59AM +0100, Aurelien Jacobs wrote:
>> On Mon, Mar 15, 2010 at 01:34:56PM +0100, Giorgio wrote:
>> > Hello :)
>> >
>> > This patch fixes offsetting in Theora video files.
>>
>> You may be interested to fix this issue also with -demuxer lavf  (and
>> thus with fftheora). This is especially interesting as now fftheora is
>> faster than libtheora.

I'd like to see this fixed in fftheora too, but I've never looked at
the code :) Plus, when I try to use -demuxer lavf I keep getting
'[VD_FFMPEG] DRI failure.' no matter what vo I use (I tried x11, xv,
gl, gl2, sdl) and this makes decoding slower.

> I don't really like doing this at the decoder level unless the cropping is
> at most 16 pixels. Anything beyond that is IMO a task for video filters.

Yes, I think using a filter would be a better idea. But, I don't
understand the '16 pixels' part... the cropping is at most 2 pixels
(in case of odd offsets and 4:2:0 files, but it is generally
recommended that the offsets and sizes should be multiples of 2, so
"good" files will not be cropped at all) if you consider that outside
the picture area there no sensible data as stated in the format
specification: "The portions of the frame which lie outside the
picture region may contain arbitrary image data, so the frame must be
cropped to the picture region before display."

I've updated the patch to handle all the cases (now both offsets and
picture sizes can be odd or even) and fixed some mistakes, so now I
was able to use several vo to export images (pnm,png) and apply
several filters (flip,mirror,rotate...).

Giorgio Vazzana
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