Debayering (bayer 2 rgb) with opengl glshader gst-1.5.1

[Christian Sell]

Hi,
 
I am not the ultimate expert on GL shader programming, but I dont think you can
do without a vertex shader at all. In the particular case of the debayering
stuff, the vertex shader computes the values of xCoord, yCoord and center based
on the previously mentioned input parameters. These values are then used by the
pixel shader. So unless the input parameters are correctly set, nothing will
work.
 
chris

> Hamdi Rakkez <hamdi.rakez.selotec at gmail.com> hat am 19. August 2015 um 13:26
> geschrieben:
> 
>  Great explanation Christian.
>      * Actually I am using only the pixel shader file.
>      * The source is successfully entered from gstreamer to the shader.
>      * SourceSize and first red are in the vertex shader which I am not using.
>  Question :
>      * Is it necessary, for the debayering to work, to use both files (vertex
> and pixel shader). If yes, is it possible to have them both in one file so I
> can deal with input parameters statically.
>  thanks.
>   
>  Best,
>  Hamdi
>   
> 
>  On Wed, Aug 19, 2015 at 12:15 PM, Christian Sell <christian at gsvitec.com
> <mailto:christian at gsvitec.com> > wrote:
>    > >    Hello,
> >     
> >    I am not sure how the glshader element works, but I do know how that
> > shader program works, because we are successfully using it. Actually, we are
> > using the GL variant for client-side debayering (outside of gstreamer,
> > immediately before the data is displayed) and the CL variant for debayering
> > inside the gstreamer pipeline with a custom element.
> >     
> >    There are 2 things I am doubtful with regard to the glshader element:
> >     
> >    1. the debayering code consists of a vertex and a pixel (aka fragment)
> > shader. How are these integrated into glshader?
> >    2. the code expects several parameters to be set from the outside, namely
> > "source" (input buffer), "sourceSize" (an array with values width, height,
> > 1/width, 1/height) and "firstRed" (a 0/1 combination describing the bayer
> > pattern in use)
> >     
> >    I dont see how these prerequistes would be met by glshader..
> >     
> >    regards,
> >    Chris
> >     
> > 
> >     > > > Hamdi Rakkez <hamdi.rakez.selotec at gmail.com
> >     > > > <mailto:hamdi.rakez.selotec at gmail.com> > hat am 19. August 2015 um
> >     > > > 12:06 geschrieben:
> > > 
> > > 
> > >     Hi,
> > >      
> > >     I am trying to use shaders to decode bayer images to RGB images.
> > >      
> > >     I don't want to use the bayer2rgb element.
> > >      
> > >     So, according to this
> > > http://graphics.cs.williams.edu/papers/BayerJGT09/#shaders it is possible
> > > to user gl shaders for demosaicing a bayer image.
> > >      
> > >     I have used the shader file along with glshader in a pipeline like
> > > this :
> > >      
> > >       > > > > ​gst-launch-1.0 -v filesrc location=bayer_file.avi !
> > >       > > > > avidemux ! ​glupload ! glshader location=bayerRGB.GLSL !
> > >       > > > > glimagesink​
> > > >     > > >      
> > >      
> > >     But, I have a very noisy result, and an image of the result is
> > > attached to this Email.​
> > >      
> > >     Any ideas why such behavior.
> > >      
> > >     Thank you
> > >     _______________________________________________
> > >     gstreamer-devel mailing list
> > >     gstreamer-devel at lists.freedesktop.org
> > > <mailto:gstreamer-devel at lists.freedesktop.org>
> > >     http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
> > > 
> > >    > > 
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> 

 
Christian Sell

GS Vitec GmbH
Im Ziegelhaus 6-8
D-63571 Gelnhausen

mail: christian at gsvitec.com
mobil: +49 (0) 173 5384289

Tel: +49 (0) 6051 601.26-90
Fax: +49 (0) 6051 601.26-91
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