onboard camera issue on TX2

Robotics & Edge Computing Jetson & Embedded Systems Jetson TX2
1

if I change define

VideoCapture cap(“nvcamerasrc ! video/x-raw(memory:NVMM), width=(int)1280, height=(int)720,format=(string)I420, framerate=(fraction)24/1 ! nvvidconv flip-method=2 ! video/x-raw, format=(string)BGRx ! videoconvert ! video/x-raw, format=(string)BGR ! appsink”);

to

VideoCapture cap(0);

the camera can open, but can’t see anything(blackscreen).

I also try cheese, It’s blackscreen too.

python2.7 opencv3.2

2

VideoCapture cap(0) uses V4L interface with video device in /dev/video0.

The problem is that onboard camera only works with 10 bits modes, and this would give bayer frames, while opencv expects 8 bits BGR. You may check: [url]https://devtalk.nvidia.com/default/topic/1028611/jetson-tx2/is-there-a-parameter-for-enable-disable-the-tx2-on-board-camera-/post/5232247/#5232247[/url].
With nvcamerasrc, debayering (and more) is done with the ISP.

If you have USB camera, it should be /dev/video1 and you may be able to use VideoCapture cap(1) for it.

3

the camera can be converted to the type of USB camera via the video loopback module

4

Hi Andrey,

May you please give more details ? I’ve installed v4l2loopback, I’m able to create a virtual /dev/video1, but I’m not able to use it with gstreamer v4l2src plugin.

Thanks for sharing the steps you use.

5

Hi Honey_Patouceul
Thank you for your question.

1.$ sudo su
2.$ cd /usr/src/linux-headers-4.4.38-tegra
3.$ make modules_prepare
4.$ mkdir v4l2loopback
5.$ cd v4l2loopback
6.$ git clone https://github.com/umlaeute/v4l2loopback.git
7.$ cd v4l2loopback
8.$ make
9.$ make install
10.$ modprobe v4l2loopback devices=1 video_nr=2 exclusive_caps=1
11.$ echo options v4l2loopback devices=1 video_nr=2 exclusive_caps=1 > /etc/modprobe.d/v4l2loopback.conf
12.$ echo v4l2loopback > /etc/modules
13.$ update-initramfs -u
14.$ gst-launch-1.0 nvcamerasrc ! 'video/x-raw(memory:NVMM), width=(int)1920, height=(int)1080, format=(string)I420, framerate=(fraction)30/1' ! nvtee ! nvvidconv ! 'video/x-raw, format=(string)I420, framerate=(fraction)30/1' ! tee ! v4l2sink device=/dev/video2

Steps 11,12,13 apply the module load permanently while the step 10 loads the module until next reboot.
However, now it mpi camera stream is rolling under /dev/video2 as if generated by a usb camera. In my case I am able to use Internet browser web video chat with executing in a new terminal:

1. $ export DISPLAY=:0
2. $ chromium-browser

May be if you apply the step 14 you will be able to access the stream somehow.
However, my experience is bounded with “in-browser use for web-video-chat purpose”.

But I assume that video is streamed under /dev/video2 as a normal usb camera generated stream and can be accessed using “VideoCapture cap(2);” , and unless “gstreamer v4l2src plugin” conflicts with “gst-launch-1.0” being running simultaneously, it possibly can be used, somehow.

Could you define how do you call /dev/video1 with the gstreamer v4l2src plugin ?

6

Hi Andrey,

I am unable to use v4l2src plugin, but indeed I made this pipeline

gst-launch-1.0 nvcamerasrc ! 'video/x-raw(memory:NVMM), width=(int)1920, height=(int)1080, format=(string)I420, framerate=(fraction)30/1' ! nvtee ! nvvidconv ! 'video/x-raw, format=(string)BGRx, framerate=(fraction)30/1' ! videoconvert ! 'video/x-raw,format=BGR' ! v4l2sink device=/dev/video2

and then Opencv works with cv::VideoCapture cap(2);

Thanks a lot for sharing.

7

you may find some other useful tricks at jetson use cases