解释一下下面的代码int key_value=cv::waitKey(1); cout<<"key_value:"<<key_value<<endl; switch (key_value) { case 's': cout<<"key_value:"<<key_value<<endl; shutdown(); break; // case 'S': cout<<"key_value:"<<key_value<<endl; break; // case '\r':break; // case 0x18:break;//cancel // case 0x1B:break;//escape default:break; }

这段代码的作用是等待用户输入一个键盘按键，并将按键的ASCII码值赋给变量key_value。然后根据不同的按键值，进行不同的操作。如果用户按下了字母s，则调用shutdown()函数；如果按下了字母S，则什么也不做；如果按下了回车键，则什么也不做；如果按下了取消键或者Esc键，则什么也不做；如果按下的是其他键，则什么也不做。

相关问题

import cv2 cap = cv2.VideoCapture(0) cap.set(cv2.CAP_PROP_FRAME_WIDTH,1080) #set window's width and height cap.set(cv2.CAP_PROP_FRAME_HEIGHT,780) while True: _, frame = cap.read() hsv_frame = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV) height,width,_ = hsv_frame.shape wx = int(width/2) # center wy = int(height/2) center_color = hsv_frame[wy,wx] #中心点HSV像素值 hue_value = center_color[0] #取Hue if hue_value < 5: color = 'RED' elif hue_value < 22: color = 'ORANGE' elif hue_value < 33: color = 'YELLOW' elif hue_value < 78: color = 'GREEN' elif hue_value <131: color = 'BLUE' elif hue_value < 167: color = 'VIOLET' else: color ='RED' bgr_color = frame[wy,wx] b,g,r = int(bgr_color[0]),int(bgr_color[1]),int(bgr_color[2]) cv2.circle(frame,(wx,wy),5,(0,255,0),3) # center (x,y) cv2.putText(frame,color,(10,50),0,1,(b,g,r),2) cv2.imshow('frame',frame) key = cv2.waitKey(1) if key ==27: break cap.release() cv2.destroyAllWindows()

这段代码使用OpenCV库来捕获摄像头视频流，并根据中心像素点的颜色判断出相应的颜色。代码中首先设置了视频窗口的宽度和高度，然后进入一个无限循环中。循环中使用`cap.read()`函数读取视频的每一帧，然后将帧转换为HSV颜色空间。接着，获取图像的高度和宽度，并计算出中心点的坐标。通过中心点的坐标，可以获取中心像素点的颜色值，并提取出Hue值。根据Hue值的范围，判断出相应的颜色，并在视频帧上绘制出中心点和颜色文字。最后使用`cv2.imshow()`函数显示帧，按下ESC键退出循环，释放摄像头资源并关闭窗口。

请问你还有其他问题吗？

将以下程序转换成python程序 #include <opencv2/opencv.hpp> #include <iostream> #include<ctime> int main(int argc,char** argv) { clock_t start,end; int cam_num = 1; // 1,2 the number of cameras used // nano_id dev_id port_id 位置 // 13 0 9202 下巴 // 13 1 9201 前方 // 14 0 9203 左方 // 14 1 9204 右方 // 15 0 9205 腹部（默认） std::string IpLastSegment = "15"; int cam_id = 0; // the id of the camera used if cam_num is 1 if (argc>=2) cam_id = std::atoi(argv[1]); int udpPORT1 = 9201; // port_id of the camera which was used int udpPORT2 = 9202; // port_id of the camera which was used std::string udpstrPrevData = "udpsrc address=192.168.123."+ IpLastSegment + " port="; std::string udpstrBehindData = " ! application/x-rtp,media=video,encoding-name=H264 ! rtph264depay ! h264parse ! omxh264dec ! videoconvert ! appsink"; std::string udpSendIntegratedPipe1 = udpstrPrevData + std::to_string(udpPORT1) + udpstrBehindData; std::string udpSendIntegratedPipe2 = udpstrPrevData + std::to_string(udpPORT2) + udpstrBehindData; std::cout<<"udpSendIntegratedPipe1:"<<udpSendIntegratedPipe1<<std::endl; std::cout<<"udpSendIntegratedPipe2:"<<udpSendIntegratedPipe2<<std::endl; cv::VideoCapture cap1(udpSendIntegratedPipe1); cv::VideoCapture cap2(udpSendIntegratedPipe2); if(!cap1.isOpened()) return 0 ; if(!cap2.isOpened()) return 0 ; cv::Mat frame1, frame2; while(1) { start=clock(); //程序开始计时 cap1 >> frame1; cap2 >> frame2; if(frame1.empty()) break; if(frame2.empty()) break; imshow("video1", frame1); imshow("video2", frame2); end=clock(); double endtime=(double)(end-start)/CLOCKS_PER_SEC; std::cout << "FPS:"<<1/endtime<<"/s"<<std::endl; //ms为单位 char key = cv::waitKey(1); if(key == 27) // press ESC key break; } cap1.release();//释放资源 cap2.release();//释放资源 } return 0; }

以下是将该程序转换为Python程序的代码：

import cv2

def main(cam_id):
cam_num = 1 # 1,2 the number of cameras used
IpLastSegment = "15"
udpPORT1 = 9201 # port_id of the camera which was used
udpPORT2 = 9202 # port_id of the camera which was used
udpstrPrevData = "udpsrc address=192.168.123." + IpLastSegment + " port="
udpstrBehindData = " ! application/x-rtp,media=video,encoding-name=H264 ! rtph264depay ! h264parse ! omxh264dec ! videoconvert ! appsink"
udpSendIntegratedPipe1 = udpstrPrevData + str(udpPORT1) + udpstrBehindData
udpSendIntegratedPipe2 = udpstrPrevData + str(udpPORT2) + udpstrBehindData
print("udpSendIntegratedPipe1:", udpSendIntegratedPipe1)
print("udpSendIntegratedPipe2:", udpSendIntegratedPipe2)
cap1 = cv2.VideoCapture(udpSendIntegratedPipe1)
cap2 = cv2.VideoCapture(udpSendIntegratedPipe2)
if not cap1.isOpened():
return 0
if not cap2.isOpened():
return 0
while True:
start = cv2.getTickCount() # 程序开始计时
ret1, frame1 = cap1.read()
ret2, frame2 = cap2.read()
if not ret1:
break
if not ret2:
break
cv2.imshow("video1", frame1)
cv2.imshow("video2", frame2)
end = cv2.getTickCount()
elapsed_time = (end - start) / cv2.getTickFrequency()
fps = 1 / elapsed_time
print("FPS:", fps, "/s") # ms为单位
key = cv2.waitKey(1)
if key == 27: # press ESC key
break
cap1.release() # 释放资源
cap2.release() # 释放资源

if __name__ == "__main__":
cam_id = 0 # the id of the camera used if cam_num is 1
main(cam_id)