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

[Hamdi Rakkez]

Very very interesting information.

The question is :

Is it possible to use both files with glshader gst element ?
Do glshader go along with vertex files ?

thank you.

On Wed, Aug 19, 2015 at 1:05 PM, Christian Sell <christian at gsvitec.com>
wrote:

> I have verified it: to do any rendering at all, a GL program must consist
> of at least a vertex and a fragment shader. These work together. Roughly
> speaking, the vertex shader determines the working position, and the
> fragment shader determines the work to be done at that position.
>
>
> Christian Sell <christian at gsvitec.com> hat am 19. August 2015 um 13:58
> geschrieben:
>
>
> 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>
> 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> 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
> <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
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>
> Christian Sell
>
> GS Vitec GmbH
> Im Ziegelhaus 6-8
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>
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>
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>
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