HDMI video src

[Nicolas Dufresne]

Le jeudi 11 février 2021 à 10:13 -0600, yasoua a écrit :
> Thank you for your answer.
> 
> Actually i am working on a module based on NXP imx8 processor. ( linux)
> The module includes also two microdisplays which are managed by MachXO2
> fpga. Data or images displayed in the microdisplays come from hdmi input. 
> 
> I have lenses in front of each microdispaly, so we see deformations.
> 
> When i asked this question i thougth that the deformations seen come from
> the source ( hdmi video input) thas is why i was looking for a way to
> capture the HDMI video input and apply cameracalibte and cameraundistort
> filters to it. 

I own an USB / HDMI capture device that is UVC and works just fine with v4l2src.
I'm also working on some other adapters, which in fact required a tad of work on
GStreamer side for my use case:

https://gitlab.freedesktop.org/gstreamer/gst-plugins-good/-/merge_requests/870

But with some v4l2-ctl calls and v4l2src it worked otherwise. On IMX8, an HDMI
receiver would be hooked to the "camera" interface, hence should be very similar
to using RPi HDMI capture. Though v4l2src (or gstreamer-imx equivalent) is
likeky the right GStreamer elements.


> 
> UPDATE : i realized that the deformations are due to lenses placed in front
> of each microdisplay. When i removed them i didn't see any distortion.
> The issue or the question : is there  any way to correct this distortion
> using gstreamer elements  while keeping my optic (lenses).

My best bet would be:

https://gstreamer.freedesktop.org/documentation/opencv/cameracalibrate.html?gi-language=c
https://gstreamer.freedesktop.org/documentation/opencv/cameraundistort.html?gi-language=c

Hopefully you have access to an accelerated version of OpenCV (e.g. through
OpenCL or such). I know there was some lense correction done in GL too, for some
VR use case, but that does not seems to be in the upstream GStreamer. Hopefully
real experts on the subject will reply here.

> 
> I tried to be clear so that you could understand my issue and you could help
> me.
> 
> For the deckvidosrc , do you mean decklinkvideosrc ? i didn't find any
> deckvidosrc in gstreamer documentation.
> 
> Best regards 
>  
> 
> 
> 
> --
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