How to avoid aliasing artifacts using X11/GLES2 to display interlaced YUYV camera output?

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How to avoid aliasing artifacts using X11/GLES2 to display interlaced YUYV camera output?

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vikaspatil
Senior Contributor I

Hi Community,

I have a requirement where I need to display camera capture (interlaced YUYV) using v4l2 capture/X11/GLES2.0. I am able to write a test application which captures via v4l2 capture apis and using X11/GLES able to show it. However the displayed image doesn't look smooth, instead I am seeing jaggy (saw kind)/aliasing artifacts.

Some more information:

- Camera outputs CVBS NTSC format. here it is interlaced YUYV

- I am using glTexDirectVIV() extension with GL_VIV_YUY2 input format.

See the attached bmp image with artifacts here.

artifact.bmp

If I try imx-test/mxc_4l2_tvin.out test with "-m 2 or -m 0" option, camera capture image is coming correctly (smooth).

./mxc_v4l2_tvin.out -ow 800 -oh 480 -f YUYV -m  (Result: aliasing kind artifacts)

./mxc_v4l2_tvin.out -ow 800 -oh 480 -f YUYV -m 0 (Result: Good)

./mxc_v4l2_tvin.out -ow 800 -oh 480 -f YUYV -m 1 (Result: aliasing kind artifacts)

./mxc_v4l2_tvin.out -ow 800 -oh 480 -f YUYV -m 2 (Result: Good)

Looking at the source of mxc_v4l2_tvin.c, it seems following code makes camera capture to come correctly on display. Which in turn sets required value to VDI Control register (i.e. IPU_VDI_C) when v4l2 output path is getting used.

   "output_buf.field =  V4L2_FIELD_INTERLACED_BT;"

I captured the VDI Control register value and tried to set it using devmem before running my application as follows but it didn't help.

i.e.

#devmem 0x2668004 32 0x42083332

Could anyone give some ideas/inputs/suggestions to avoid artifacts using X11/GLES2.0?

Is there anyway to use the IPU VDI functionality as above (i.e. mxc_v4l2_tvin) with the output/display pipeline with X11/GLES2.0/EGL/FB?

Thanking you all in advance and waiting for replies.

Regards,

Vikash

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Johnli
NXP Employee
NXP Employee

    FAE feedback our i.MX6X+intersil68xx source codes and test applicaiton to customer, but customer said if enable the VDI, will have green screen, disable it is ok.

    customer use the ADV7180 but we use the intersil. need AE's comments.

Br

John.li

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