Jetson 学习笔记(六):cv2调用CSI摄像头(jetson nx/nano)、打开海康摄像头、打开电脑摄像头

海康摄像头

import cv2
import multiprocessing as mp

num = 0
def image_put(q, name, pwd, ip, channel):
    #cv2.namedWindow(ip, cv2.WINDOW_NORMAL)
    global url
    url="rtsp://%s:%s@%s:%s//Streaming/Channels/1" \
                           % (name, pwd, ip, channel)
    cap = cv2.VideoCapture(url)
    # 获取视频帧率
    fps = cap.get(cv2.CAP_PROP_FPS)
    print('fps: ', fps)
    if cap.isOpened():
        print('HIKVISION1')
        print('camera ' + ip + " connected.")
    while cap.isOpened():
        ret, frame = cap.read()
        # 抓取图片不成功再重新抓取
        if not ret:
            cap = cv2.VideoCapture("rtsp://%s:%s@%s:%s//Streaming/Channels/1" \
                                   % (name, pwd, ip, channel))
            print('HIKVISION2')
            ret, frame = cap.read()
            frame = cv2.resize(frame, (800,600))
        cv2.imshow(ip,frame)
        # Press esc on keyboard to  exit
        if cv2.waitKey(1) & 0xFF == 27:
            break
    cap.release()
# 解决进程问题
def run_multi_camera():
    user_name, user_pwd = "admin", "a12345678"
    camera_ip_l = ["10.16.14.151",]
    ports = ['556']
    mp.set_start_method(method='spawn')  # init
    queues = [mp.Queue(maxsize=2) for _ in camera_ip_l]
    processes = []
    for queue, camera_ip,port in zip(queues, camera_ip_l,ports):
        processes.append(mp.Process(target=image_put, args=(queue, user_name, user_pwd, camera_ip,port)))
    for process in processes:
        process.daemon = True
        process.start()
    for process in processes:
        process.join()
if __name__ == '__main__':
    run_multi_camera()

电脑摄像头

import cv2
cap = cv2.VideoCapture(0)
while cap.isOpened():
    cv2.namedWindow('Pc-camera', cv2.WINDOW_NORMAL)
    ret, frame = cap.read()
    frame = cv2.resize(frame, (800,600))
    cv2.imshow('Pc-camera',frame)
    # Press esc on keyboard to  exit
    if cv2.waitKey(1) & 0xFF == 27:
        break
cap.release()
cv2.destroyWindow()

Jetson NX/Nano-CSI

方法1

使用Gstreamer读取CSI摄像头主要分为3个步骤：创建Gstreamer管道；将管道绑定opencv的视频流；逐帧提取和显示。下面首先给出基于Python的详细代码：

import cv2

# 设置gstreamer管道参数
def gstreamer_pipeline(
    capture_width=1280, #摄像头预捕获的图像宽度
    capture_height=720, #摄像头预捕获的图像高度
    display_width=1280, #窗口显示的图像宽度
    display_height=720, #窗口显示的图像高度
    framerate=60,       #捕获帧率
    flip_method=0,      #是否旋转图像
):
    return (
        "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"
        % (
            capture_width,
            capture_height,
            framerate,
            flip_method,
            display_width,
            display_height,
        )
    )


if __name__ == "__main__":
    capture_width = 1280
    capture_height = 720
    display_width = 1280
    display_height = 720
    framerate = 60
    flip_method = 0

    # 创建管道
    print(gstreamer_pipeline(capture_width,capture_height,display_width,display_height,framerate,flip_method))

    #管道与视频流绑定
    cap = cv2.VideoCapture(gstreamer_pipeline(flip_method=0), cv2.CAP_GSTREAMER)

    if cap.isOpened():
        window_handle = cv2.namedWindow("CSI Camera", cv2.WINDOW_AUTOSIZE)

        # 逐帧显示
        while cv2.getWindowProperty("CSI Camera", 0) >= 0:
            ret_val, img = cap.read()
            cv2.imshow("CSI Camera", img)

            keyCode = cv2.waitKey(30) & 0xFF         
            if keyCode == 27:# ESC键退出
                break

        cap.release()
        cv2.destroyAllWindows()
    else:
        print("打开摄像头失败")

方法2

通过jetcam来运行CSI摄像头(jetcam是用于NVIDIA jetson的易于使用的python摄像头界面)
安装过程：
https://blog.csdn.net/weixin_45569617/article/details/113934118
具体运行代码

from jetcam.csi_camera import CSICamera
import cv2

camera0 = CSICamera(capture_device=0, width=224, height=224)
#camera1 = CSICamera(capture_device=1, width=224, height=224)
image0 = camera0.read()
print(image0.shape)
#image1 = camera1.read()
#print(image1.shape)
print(camera0.value.shape)
#print(camera1.value.shape)
while 1:
    image0 = camera0.read()
    #image1 = camera1.read()
    cv2.imshow("CSI Camera0", image0)
    #cv2.imshow("CSI Camera1", image1)
    kk = cv2.waitKey(1)
    if kk == ord('q'):  # 按下 q 键，退出
        break

Jetson Nano/Nx-USB

先判断是否存在USB摄像头
1.如何是开机插上的摄像头就应该先关机重启之后才会显示
2.开机，输入ls /dev/video* 看看是不是有摄像头设备
3.输入nvgstcapture 一般来说就可以将摄像头直接打开，如果需要关闭直接关闭终端就好了
4.要是不显示就更新一下，sudo apt-get update sudo apt-get upgrade

下面是执行的代码
CSI摄像头的标识为0，因此这个USB摄像头的标识为1，这个可以在实际使用时通过测试来得到。另外，上述代码中对图像的尺寸做了限制，如果宽度超过800，则等比的缩放图像再显示。

import cv2

 #创建摄像头捕获模块
cap = cv2.VideoCapture(1)

#创建窗口
window_handle = cv2.namedWindow("USB Camera", cv2.WINDOW_AUTOSIZE)

# 逐帧显示
while cv2.getWindowProperty("USB Camera", 0) >= 0:
    ret_val, img = cap.read()
    print(img.shape)

    # 图像太大需要调整
    height, width = img.shape[0:2]
    if width>800:
        new_width=800
        new_height=int(new_width/width*height)
        img = cv2.resize(img, (new_width,new_height))

    cv2.imshow("USB Camera", img)

    keyCode = cv2.waitKey(30) & 0xFF         
    if keyCode == 27:# ESC键退出
        break

#释放资源
cap.release()
cv2.destroyAllWindows()