如何解决无法在 Jetson Xavier 的 python 中使用 OpenCV 捕获视频
我正在尝试在 Jetson Xavier (ubuntu 18) 上读取相机图像。我正面临一个问题。当我运行以下代码时,它会发出警告并显示黑色(完整)图像。
[ WARN:0] global /home/nvidia/host/build_opencv/nv_opencv/modules/videoio/src/cap_gstreamer.cpp (933) 打开 OpenCV | GStreamer 警告:无法查询视频位置:状态=0,值=-1,持续时间=-1
cam=cv2.VideoCapture(0)
if cam.isOpened():
grab,img = cam.read()
if grab is True:
cv2.imshow('sample image',img)
else:
print(f"Image not found")
else:
print("Camera not openedd")
cv2.waitKey(0) # waits until a key is pressed
cv2.destroyAllWindows() # destroys the window showing image
如果我使用 'dev/video0' 来读取图像,即
cam=cv2.VideoCapture('dev/video0')
[ WARN:0] global /home/nvidia/host/build_opencv/nv_opencv/modules/videoio/src/cap_gstreamer.cpp (711) 打开 OpenCV | GStreamer 警告:打开垃圾箱时出错:没有元素“dev” [ WARN:0] global /home/nvidia/host/build_opencv/nv_opencv/modules/videoio/src/cap_gstreamer.cpp (480) isPipelinePlaying OpenCV | GStreamer 警告:GStreamer:尚未创建管道 相机未打开
然后我创建了 gstream 字符串并将其传递给视频捕获,如下所示。 字符串如下
gstr = 'varguscamerasrc ! video/x-raw(memory:NVMM),width=(int)1920,height=(int)1080,format=(string)NV12,framerate=(fraction)60/1 ! nvvidconv flip-method=0 ! video/x-raw,width=(int)1280,height=(int)720,format=(string)BGRx ! videoconvert ! video/x-raw,format=(string)BGR ! appsink'
cap = cv2.VideoCapture(gstr,cv2.CAP_GSTREAMER)
我收到以下错误
Error generated. /dvs/git/dirty/git-master_linux/multimedia/nvgstreamer/gst-nvarguscamera/gstnvarguscamerasrc.cpp,execute:645 No cameras available
(python3:15402): GStreamer-CRITICAL **: 19:08:54.835: gst_mini_object_set_qdata: assertion 'object != NULL' Failed
[ WARN:0] global /home/nvidia/host/build_opencv/nv_opencv/modules/videoio/src/cap_gstreamer.cpp (933) open OpenCV | GStreamer warning: Cannot query video position: status=0,value=-1,duration=-1
Traceback (most recent call last):
我是 jetson 的新手,请指导我。谢谢
解决方法
您可以尝试以下代码。还要确保您已从源代码安装 OpenCV,而不是使用 pip,因为当您从 pip 安装 OpenCV 时,Jetson Nano 和 Xavier 会出现一些问题。
import numpy as np
import cv2
cap = cv2.VideoCapture(0)
while(True):
# Capture frame-by-frame
ret,frame = cap.read()
# Our operations on the frame come here
gray = cv2.cvtColor(frame,cv2.COLOR_BGR2GRAY)
# Display the resulting frame
cv2.imshow('frame',gray)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
# When everything done,release the capture
cap.release()
cv2.destroyAllWindows()
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