GStreamer: Error when accessing onboard camera

Autonomous Machines Jetson & Embedded Systems Jetson TX2
1

Hey folk,

when i try to access the onboard camera with a script using opencv (not tegra version) i get the following error:

VIDEOIO ERROR: V4L: device : Unable to query number of channels
GStreamer: Error opening bin: empty pipeline not allowed

Does anyone please has a solution for me to fix that issue?

Thank you very much, tobi

2

So for example, if i excecute the following script to show the onboard camera image using opencv:

import sys
import cv2

def read_cam():
    cap = cv2.VideoCapture("nvcamerasrc ! video/x-raw(memory:NVMM), width=(int)640, height=(int)480,format=(string)I420, framerate=(fraction)30/1 ! nvvidconv flip-method=2 ! video/x-raw, format=(string)BGRx ! videoconvert ! video/x-raw, format=(string)BGR ! appsink")
    if cap.isOpened():
        cv2.namedWindow("demo", cv2.WINDOW_AUTOSIZE)
        while True:
            ret_val, img = cap.read();
            cv2.imshow('demo',img)
            cv2.waitKey(10)
    else:
       print "camera open failed"

    cv2.destroyAllWindows()


if __name__ == '__main__':
    read_cam()

I get the following error message:

Opening in O_NONBLOCKING MODE 
VIDEOIO ERROR: libv4l unable convert to requested pixfmt
Opening in BLOCKING MODE 
VIDEOIO ERROR: libv4l unable to ioctl VIDIOCSPICT

OpenCV Error: Unspecified error (GStreamer: unable to start pipeline
) in cvCaptureFromCAM_GStreamer, file /home/nvidia/src/opencv-3.4.0/modules/videoio/src/cap_gstreamer.cpp, line 890
VIDEOIO(cvCreateCapture_GStreamer(CV_CAP_GSTREAMER_V4L2, reinterpret_cast<char *>(index))): raised OpenCV exception:

/home/nvidia/src/opencv-3.4.0/modules/videoio/src/cap_gstreamer.cpp:890: error: (-2) GStreamer: unable to start pipeline
 in function cvCaptureFromCAM_GStreamer

OpenCV Error: Assertion failed (scn == 3 || scn == 4) in cvtColor, file /home/nvidia/src/opencv-3.4.0/modules/imgproc/src/color.cpp, line 11111
Traceback (most recent call last):
  File "opencv_cam_tester.py", line 11, in <module>
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
cv2.error: /home/nvidia/src/opencv-3.4.0/modules/imgproc/src/color.cpp:11111: error: (-215) scn == 3 || scn == 4 in function cvtColor

I am not very familar with GStreamer and V4L2 so it would be very helpful to get some help to fix this. Thank you very much.

3

Hi,
We have deprecated nvcamerasrc plugin in r32 releases. Do you use r28 releases? You may check if you can run

$ gst-inspect-1.0 nvcamerasrc
$ gst-launch-1.0 nvcamerasrc ! nvoverlaysink

The following command shows the release version:

$ head -1 /etc/nv_tegra_release
4

hey @DaneLLL, if i exucute the first command, i get the following error:

No such element or plugin 'nvcamerasrc'

if i than execute the second command i get the following error:

WARNING: erroneous pipeline: no element "nvcamerasrc"

Executing the third command runs without error and prints:

# R32 (release), REVISION: 2.0, GCID: 15966166, BOARD: t186ref, EABI: aarch64, DATE: Wed Jul 17 00:26:04 UTC 2019

Do you have a idea to get my issue fixed?

thank you.

5

Hi,
Please use nvarguscamerasrc.

6

dear @DaneLLL can you please give me a hint on how to install and use this? i am not very familar with camera pipeline software like this.

thank you very much

7

iam sorry, this was a little bit stupid written, what i meant is, could you give me a hint for a nvarguscamerasrc pipeline stream to use

8

I am using the following pipeline stream but it causes errors:

'nvarguscamerasrc ! '
    'video/x-raw(memory:NVMM), '
    'width=(int)%d, height=(int)%d, '
    'format=(string)NV12, framerate=(fraction)%d/1 ! '
    'nvvidconv flip-method=%d ! '
    'video/x-raw, width=(int)%d, height=(int)%d, format=(string)BGRx ! '
    'videoconvert ! '
    'video/x-raw, format=(string)BGR ! appsink'

If i run it inside opencvs VideoCapture it gives error:

Error generated. /dvs/git/dirty/git-master_linux/multimedia/nvgstreamer/gst-nvarguscamera/gstnvarguscamerasrc.cpp, execute:532 Failed to create CaptureSession

and

Unable to query number of channels
9

Hi,
we have verified below steps:
[url]https://devtalk.nvidia.com/default/topic/1057460/jetson-tx2/custom-built-opencv-3-4-0-following-nvidia-advice-not-working/post/5363355/#5363355[/url]
Please check if you can run the C code, and then adapt the pipeline to your python code.

10

Hi!
I’m working on running yolo on Tx2 Dev kit. I have installed all of requirements for yolo, OpenCV, CUDA, Cudnn.
I’ve tested if the onboard camera’s working via gstreamer : gst-launch-1.0 nvarguscamerasrc ! nvvidconv ! xvimagesink
It works properly.
Then, I tried to run yolo by your code ./darknet detector demo cfg/coco.data cfg/yolo.cfg yolo.weights “nvcamerasrc ! video/x-raw(memory:NVMM), width=(int)1280, height=(int)720,format=(string)I420, framerate=(fraction)30/1 ! nvvidconv flip-method=0 ! video/x-raw, format=(string)BGRx ! videoconvert ! video/x-raw, format=(string)BGR ! appsink”
The result is “Video-stream stopped!”
How could i track the issue?