# pxp\_v4l2\_test program without output on LCD display

**URL:** https://forums.digi.com/t/pxp-v4l2-test-program-without-output-on-lcd-display/19760
**Category:** Linux
**Tags:** linux, test, imx6ul, pxp
**Created:** [August 2, 2018, 2:39pm UTC](https://forums.digi.com/t/pxp-v4l2-test-program-without-output-on-lcd-display/19760 "2018-08-02T14:39:38Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![dzhou](https://avatars.discourse-cdn.com/v4/letter/d/ecd19e/32.png) [@dzhou](https://forums.digi.com/u/dzhou)
#### Post date: [August 2, 2018, 2:39pm UTC](https://forums.digi.com/t/pxp-v4l2-test-program-without-output-on-lcd-display/19760/1 "2018-08-02T14:39:38Z")

</div>

Hi,

I have imx6ul dev board. I also compiled imx\_test-5.7. In the test package, there is a program pxp\_v4l2\_test.out under the unit\_tests folder. I run :

pxp\_v4l2\_test.out -sx 350 -sy 240 -res 350:240 -dst 0:0:350:240 -a 100 -a 100 -w 5 t\_yuv420\_il.yuv BLANK

The program output:

unable to open /dev/video for output, continue searching device.  
Found v4l2 output device /dev/video0.  
V4L output 0 (0x8e100000): PxP Display Output  
Video input format: 350x240 YUV 4:2:0 Planar  
request count 6  
win.w.l/t/w/h = 0/0/350/240  
crop.c.l/t/w/h = 0/0/350/240  
PxP processing: start…  
total time for 1 frames = 2500 us, 400 fps  
complete  
VIDIOC\_STREAMOFF: Invalid argument

From the document:

Expected Result | The video streaming can be viewed on LCD.

But there is no image or video displayed on the LCD.

I also installed gstreamer. it can play back a video clip onto the v4l2sink, and video clip is successfully rendered onto the LCD screen.

For the pxp\_v4l2\_test.out, what is missing?

Thank you,

David