Le 18/12/2014 05:11, Dan Dennedy a écrit :
On Wed, Dec 17, 2014 at 6:26 PM, Christophe Thommeret <hf...@free.fr
<mailto:hf...@free.fr>> wrote:
Hi all,
I use Shotcut to edit some things (MachinTruc doesn't support
interlace yet)
and i notice that there is no gpu based rotation filter.
The soft one is damn slow and too much aliased to my taste.
I have one in MachinTruc that could be ported to MLT.
It's implemented in a 'Size Position Rotation" filter for efficiency,
so i guess it should go in MLT's movit.rect.
Question: should the fragment shader be harcoded in movit.rect or
is there
any way for MLT to install a shader file system wide ?
Every MLT module has a directory in /usr/share/mlt/opengl that you can
put it into. See the module's Makefile to see how it installs the .yml
files. You can put it into the same directory. Then, to load it use do
something like:
string(mlt_environment("MLT_DATA")) + string("/opengl/rotate.frag")
opengl module' Makefile already creates MLT_DATA/opengl/movit
Could it go here or is it for other purpose?
I wonder how to make a multi Effect Filter, I mean a Mlt::Filter that
would combine several Movit::Effect ?
In the case of rotation, we need first to apply a PaddingEffect to
center the input image on a
square texture of size sqrt(input_width² + input_height²) + 1 (adding 1
makes sure we have transparency
all around the image since we don't want the edges to be copied on empty
parts of the output, and also
gives us antialiasing with bilinear interpolation.)
Then we have to apply a RotationEffect.
And finally the result must be cropped (auto padding should take care of
this i guess?).
Additionnaly, resampling (if any) must be done prior to rotation in case
of non square pixels
(and the RotationEffect shader needs to know this SAR)
--
Christophe Thommeret
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