[FFmpeg-soc] [RFC] Frame rotation by 90 degree

[Vitor]

Hi

Bobby Bingham wrote:
> On 3 Dec 2007 07:18:11 -0000
> "Tilak Adhya" <tilakadhya at rediffmail.com> wrote:
> 
>>   
>> Hi All,
>>
>> I am new to this mailing list. My problem is to rotate a frame by 90,
>> 180 and 270 degrees by adding/changing in FFMPEG code. For 180 degree
>> rotation, I got the vf_vflip.c file under the libavfilter folder,
>> which does the flipping, that means 180 degree rotation. But for 90
> 

[...]

> This is a very special case and can be accomplished simply by changing
> the pointer to the beginning of the frame data, and by negating the
> linesize.  This does not generalize to other rotations, which will
> require that you copy data around.
> 

[...]

> 
>> Please suggest...

Continuing what Bobby said about vflip, maybe it would be a good idea to 
use as a base not vf_vflip.c but instead vf_negate.c (which do modify 
the frame data). You can first do a filter that only work with videos 
with square dimensions and then generalize.

-Vitor