Question when run yolov3 with camera on-board

Robotics & Edge Computing Jetson & Embedded Systems Jetson TX2
1

Hi,
I have flashed my jetson TX2 with Jetpack4.3.

and I tried to run yolov3 on the TX2, it works with image detection, and then I would like to do with the camera on-board, I used this command :

./darknet detector demo cfg/coco.data cfg/yolov3.cfg yolov3.weights " nvarguscamerasrc ! 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"

And in terminal I got the follwing message :

video file:  nvarguscamerasrc ! 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
[ WARN:0] global /home/nvidia/host/build_opencv/nv_opencv/modules/videoio/src/cap_gstreamer.cpp (711) open OpenCV | GStreamer warning: Error opening bin: could not link nvarguscamerasrc0 to nvvconv0, nvarguscamerasrc0 can't handle caps video/x-raw(memory:NVMM), width=(int)1280, height=(int)720, format=(string)I420, framerate=(fraction)30/1
[ WARN:0] global /home/nvidia/host/build_opencv/nv_opencv/modules/videoio/src/cap_gstreamer.cpp (480) isPipelinePlaying OpenCV | GStreamer warning: GStreamer: pipeline have not been created
[ERROR:0] global /home/nvidia/host/build_opencv/nv_opencv/modules/videoio/src/cap.cpp (116) open VIDEOIO(CV_IMAGES): raised OpenCV exception:

OpenCV(4.1.1) /home/nvidia/host/build_opencv/nv_opencv/modules/videoio/src/cap_images.cpp:253: error: (-5:Bad argument) CAP_IMAGES: can't find starting number (in the name of file):  nvarguscamerasrc ! 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 in function 'icvExtractPattern'

and “Video-stream stoppped” repeated.

I looked the solution on the internet, I got one here : https://devtalk.nvidia.com/default/topic/1042892/jetson-agx-xavier/nvarguscamerasrc-opencv-solved-/

./darknet detector demo cfg/coco.data cfg/yolov3.cfg yolov3.weights " nvarguscamerasrc ! video/x-raw(memory:NVMM), width=(int)1920, height=(int)1080,format=(string)NV12, framerate=(fraction)30/1 ! nvvidconv flip-method=0 ! video/x-raw, format=(string)BGRx ! videoconvert ! video/x-raw, format=(string)BGR ! Appsink"

I have just changed “format=(string)I420” to “format=(string)NV12”
This command works on my Jetson TX2, and the vedio output is about 4 FPS.

So my question is why the format I420 doesn’t work but the NV12 dose, I think normally it should be ok with I420, is there any idea to make it?

thanks,

2

Hi,

nvarguscamerasrc only support NV12 format.
You can find this information with gst-inspect-1.0:

$ gst-inspect-1.0 nvarguscamerasrc
...
Pad Templates:
  SRC template: 'src'
    Availability: Always
    Capabilities:
      video/x-raw(memory:NVMM)
                  width: [ 1, 2147483647 ]
                 height: [ 1, 2147483647 ]
                 <b>format: { (string)NV12 }        <- only NV12 here</b>
              framerate: [ 0/1, 2147483647/1 ]

Thanks.