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C++雙線程調用網絡攝像頭與多線程調用多攝像頭同步執行方法詳細講解_C 語言

作者：zk_ken ? 更新時間： 2022-12-14 編程語言

在調用網絡攝像頭處理自己的算法時，當解碼的速度與算法運行的速度差太多時，會出現類似下面的錯誤

error while decoding MB 148 4, bytestream

所以需要使用兩個線程，一個線程調用攝像頭，一個線程用來處理圖像。

一、使用雙線程調用網絡攝像頭并執行算法

方法一

#include <iostream>
#include <thread>
#include <mutex>
#include <atomic>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
static std::mutex mutex;
static std::atomic_bool isOpen;
static void cameraThreadFunc(std::string camId, cv::Mat* pFrame)
{
    cv::VideoCapture capture(camId);
    //capture.set(cv::CAP_PROP_FOURCC, CV_FOURCC('M', 'J', 'P', 'G'));
    capture.set(cv::CAP_PROP_FPS, 30);
    if (!capture.isOpened()) {
        isOpen = false;
        std::cout << "Failed to open camera with index " << camId << std::endl;
    }
    cv::Mat frame;
    while (isOpen) {
        capture >> frame;
        if (mutex.try_lock()) {
            frame.copyTo(*pFrame);
            mutex.unlock();
        }
        cv::waitKey(5);
    }
    capture.release();
}
int main(int argc, char* argv[])
{
    std::string rtsps = "rtsp://admin:bs123456@192.168.1.64:554/h264/ch1/main/av_stream/1";
    isOpen = true;
    cv::Mat frame(1440, 2560, CV_8UC3);
    //cv::Mat* frame = new cv::Mat(1440, 2560, CV_8UC3);
    std::thread thread(cameraThreadFunc, rtsps, &frame); //調用攝像頭
    //std::thread thread(cameraThreadFunc, rtsps, frame);
    //*****************************************************
    //調用自己的算法處理圖像
    void* p_algorithm;
    p_algorithm = (void*)(new WindNetDetect());
    std::string net_bins = "./models/visdrone_1009-opt.bin";
    std::string net_paras = "./models/visdrone_1009-opt.param";
    int init_res = ((WindNetDetect*)p_algorithm)->init1(net_bins, net_paras);
    WindNetDetect* tmp = (WindNetDetect*)(p_algorithm);
    std::vector<Object> objects;
    //*****************************************************
    while (isOpen) {
        //*********************************
        //調用目標檢測的算法
        tmp->detect(frame, objects);
        tmp->draw_objects(frame, objects);
        //*********************************
        if (cv::waitKey(1) == 'q') {
            break;
        }
    }
    frame.release();
    isOpen = false;
    thread.join();
    return 0;
}

方法二

// video_test.cpp
#include <iostream>
#include <string>
#include <thread>
#include <mutex>
#include <atomic>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
class VideoCaptureMT {
public:
	VideoCaptureMT(int index, int height=480, int width=640);
	VideoCaptureMT(std::string filePath, int height=480, int width=640);
	~VideoCaptureMT();
	bool isOpened() {
		return m_IsOpen;
	}
	void release() {
		m_IsOpen = false;
	}
	bool read(cv::Mat& frame);
private:
	void captureInit(int index, std::string filePath, int height, int width);
	void captureFrame();
	cv::VideoCapture* m_pCapture;
	cv::Mat* m_pFrame;
	std::mutex* m_pMutex;
	std::thread* m_pThread;
	std::atomic_bool m_IsOpen;
};
VideoCaptureMT::VideoCaptureMT(int index, int height, int width)
{
	captureInit(index, std::string(), height, width);
}
VideoCaptureMT::VideoCaptureMT(std::string filePath, int height, int width)
{
	captureInit(0, filePath, height, width);
}
VideoCaptureMT::~VideoCaptureMT()
{
	m_IsOpen = false;
	m_pThread->join();
	if (m_pCapture->isOpened()) {
		m_pCapture->release();
	}
	delete m_pThread;
	delete m_pMutex;
	delete m_pCapture;
	delete m_pFrame;
}
void VideoCaptureMT::captureInit(int index, std::string filePath, int height, int width)
{
	if (!filePath.empty()) {
		m_pCapture = new cv::VideoCapture(filePath);
	}
	else {
		m_pCapture = new cv::VideoCapture(index);
	}
	m_pCapture->set(cv::CAP_PROP_FRAME_WIDTH, width);
	m_pCapture->set(cv::CAP_PROP_FRAME_HEIGHT, height);
	m_pCapture->set(cv::CAP_PROP_FPS, 30);
	m_IsOpen = true;
	m_pFrame = new cv::Mat(height, width, CV_8UC3);
	m_pMutex = new std::mutex();
	m_pThread = new std::thread(&VideoCaptureMT::captureFrame, this);
}
void VideoCaptureMT::captureFrame()
{
	cv::Mat frameBuff;
	while (m_IsOpen) {
		(*m_pCapture) >> frameBuff;
		if (m_pMutex->try_lock()) {
			frameBuff.copyTo(*m_pFrame);
			m_pMutex->unlock();
		}
		cv::waitKey(5);
	}
}
bool VideoCaptureMT::read(cv::Mat& frame)
{
	if (m_pFrame->empty()) {
		m_IsOpen = false;
	}
	else {
		m_pMutex->lock();
		m_pFrame->copyTo(frame);
		m_pMutex->unlock();
	}
	return m_IsOpen;
}
int main(int argc, char* argv[])
{
	VideoCaptureMT capture(0);
	cv::Mat frame, gray;
	while (capture.isOpened()) {
		if (!capture.read(frame)) {
			break;
		}
		cv::cvtColor(frame, gray, cv::COLOR_BGR2GRAY);
		cv::blur(gray, gray, cv::Size(3, 3));
		cv::Canny(gray, gray, 5 , 38 , 3);
		cv::waitKey(100);
		cv::imshow("image", gray);
        if (cv::waitKey(5) == 'q') {
			break;
		}
	}
	capture.release();
	return 0;
}

二、使用多線程調用多路攝像頭并同步執行多個算法

使用兩個線程調用兩個函數，get_cam1中包含了調用網絡攝像頭的類VideoCaptureMT （見上面代碼），以及調用算法。另外一個函數是一樣的。代碼如下 ：

void get_cam1()
{
	clock_t start, end, end1, end2;
	std::string rtsps = "rtsp://admin:bs123456@192.168.1.64:554/h264/ch1/main/av_stream/1";
	VideoCaptureMT capture(rtsps);
	//VideoCaptureMT capture, captureusb;
	cv::namedWindow("外接攝像頭檢測", 0);
	cv::Mat frame, gray;
	while (capture.isOpened()) {
		std::lock_guard<std::mutex> mtx_locker(mtx);
		start = clock();
		if (!capture.read(frame)) {
			break;
		}
		//gray = frame;
		end = clock();
		std::vector<Object> objects;
		tmp->detect(frame, objects);
		for (size_t i = 0; i < objects.size(); i++)
		{
			const Object& obj = objects[i];
			fprintf(stderr, "%d = %.5f at %.2f %.2f %.2f x %.2f\n", obj.label, obj.prob,
				obj.rect.x, obj.rect.y, obj.rect.width, obj.rect.height);
			cv::rectangle(frame, obj.rect, cv::Scalar(255, 0, 0));
			char text[256];
			//sprintf(text, "%s %.1f%%", class_names[obj.label], obj.prob * 100);
			sprintf(text, "%s", class_names[obj.label]);
			int baseLine = 0;
			cv::Size label_size = cv::getTextSize(text, cv::FONT_HERSHEY_SIMPLEX, 0.5, 1, &baseLine);
			int x = obj.rect.x;
			int y = obj.rect.y - label_size.height - baseLine;
			if (y < 0)
				y = 0;
			if (x + label_size.width > frame.cols)
				x = frame.cols - label_size.width;
			cv::rectangle(frame, cv::Rect(cv::Point(x, y), cv::Size(label_size.width, label_size.height + baseLine)),
				cv::Scalar(255, 255, 255), -1);
			cv::putText(frame, text, cv::Point(x, y + label_size.height),
				cv::FONT_HERSHEY_SIMPLEX, 0.5, cv::Scalar(0, 0, 0));
		}
		//cv::imwrite("./result20.jpg", image);
		cv::imshow("外接攝像頭檢測", frame);
		end2 = clock();
		float rumtime = (float)(end2 - start) / CLOCKS_PER_SEC;
		std::stringstream buf;
		buf.precision(3);//??????????
		buf.setf(std::ios::fixed);//????С??λ
		buf << rumtime;
		std::string strtime;
		strtime = buf.str();
		std::cout << "strtime1111 = " << strtime << std::endl;
		//start = end2;
		if (cv::waitKey(5) == 'q') {
			break;
		}
	}
	capture.release();
}
void get_camusb()
{
	clock_t start, end, end1, end2;
	std::string rtsps = "rtsp://wowzaec2demo.streamlock.net/vod/mp4:BigBuckBunny_115k.mp4";
	VideoCaptureMT capture(rtsps);
	cv::Mat frameusb;
	cv::namedWindow("外接攝像頭檢測1", 0);
	//void* p_algorithmusb;
	//p_algorithmusb = (void*)(new WindNetDetect());
	//std::string net_binsusb = "./models/visdrone_1009-opt.bin";
	//std::string net_parasusb = "./models/visdrone_1009-opt.param";
	//int init_res = ((WindNetDetect*)p_algorithmusb)->init1(net_binsusb, net_parasusb);
	//WindNetDetect* tmp = (WindNetDetect*)(p_algorithmusb);
	while (capture.isOpened()) {
		std::lock_guard<std::mutex> mtx_locker(mtx);
		start = clock();
		if (!capture.read(frameusb)) {
			break;
		}
		//gray = frame;
		end = clock();
		std::vector<Object> objectsusb;
		tmp->detect(frameusb, objectsusb);
		for (size_t i = 0; i < objectsusb.size(); i++)
		{
			const Object& obj = objectsusb[i];
			fprintf(stderr, "%d = %.5f at %.2f %.2f %.2f x %.2f\n", obj.label, obj.prob,
				obj.rect.x, obj.rect.y, obj.rect.width, obj.rect.height);
			cv::rectangle(frameusb, obj.rect, cv::Scalar(255, 0, 0));
			char text[256];
			//sprintf(text, "%s %.1f%%", class_names[obj.label], obj.prob * 100);
			sprintf(text, "%s", class_names[obj.label]);
			int baseLine = 0;
			cv::Size label_size = cv::getTextSize(text, cv::FONT_HERSHEY_SIMPLEX, 0.5, 1, &baseLine);
			int x = obj.rect.x;
			int y = obj.rect.y - label_size.height - baseLine;
			if (y < 0)
				y = 0;
			if (x + label_size.width > frameusb.cols)
				x = frameusb.cols - label_size.width;
			cv::rectangle(frameusb, cv::Rect(cv::Point(x, y), cv::Size(label_size.width, label_size.height + baseLine)),
				cv::Scalar(255, 255, 255), -1);
			cv::putText(frameusb, text, cv::Point(x, y + label_size.height),
				cv::FONT_HERSHEY_SIMPLEX, 0.5, cv::Scalar(0, 0, 0));
		}
		//cv::imwrite("./result20.jpg", image);
		cv::imshow("外接攝像頭檢測1", frameusb);
		end2 = clock();
		float rumtime = (float)(end2 - start) / CLOCKS_PER_SEC;
		std::stringstream buf;
		buf.precision(3);//??????????
		buf.setf(std::ios::fixed);//????С??λ
		buf << rumtime;
		std::string strtime;
		strtime = buf.str();
		std::cout << "strtime1111 = " << strtime << std::endl;
		//start = end2;
		if (cv::waitKey(5) == 'q') {
			break;
		}
	}
	capture.release();
}
int main() {
	void* p_algorithm;
	p_algorithm = (void*)(new WindNetDetect());
	std::string net_bins = "./models/visdrone_1009-opt.bin";
	std::string net_paras = "./models/visdrone_1009-opt.param";
	int init_res = ((WindNetDetect*)p_algorithm)->init1(net_bins, net_paras);
	tmp = (WindNetDetect*)(p_algorithm);
	//HANDLE hThread1 = CreateThread(NULL, 0, get_cam1, NULL, 0, NULL);
	//CloseHandle(hThread1);
	//HANDLE hThread2 = CreateThread(NULL, 0, get_camusb, NULL, 0, NULL);
	//CloseHandle(hThread2);
	std::thread thrd_1(get_cam1);
	std::thread thrd_2(get_camusb);
	thrd_1.join();
	thrd_2.join();
	while (true)
	{
		std::cout << "Main Thread Display!" << std::endl;
		Sleep(3000);
	}
	return 0;
}

運行上面的代碼時，兩個函數沒有同步運行。如下strtime1111表示一個線程調用的函數，strtime2222表示另一個線程調用的函數，能看出沒有同時調用兩個函數。

所以需對代碼進行如下改進：

static std::mutex mutexk;
void get_cam1()
{
	clock_t start, end, end1, end2;
	std::string rtsps = "rtsp://admin:bs123456@192.168.1.64:554/h264/ch1/main/av_stream/1";
	VideoCaptureMT capture(rtsps);
	cv::Mat frame;
	cv::namedWindow("ss", 0);
	while (capture.isOpened()) {
		//pthread_rwlock_rdlock(&rwlock);
		//std::lock_guard<std::mutex> mtx_locker(mtx);
		start = clock();
		if (!capture.read(frame)) {
			break;
		}
		if (mutexk.try_lock()) {
			//gray = frame;
			end = clock();
			std::vector<Object> objects;
			tmp->detect(frame, objects);
			//tmp->draw_objects(frame, objects);
			for (size_t i = 0; i < objects.size(); i++)
			{
				const Object& obj = objects[i];
				fprintf(stderr, "%d = %.5f at %.2f %.2f %.2f x %.2f\n", obj.label, obj.prob,
					obj.rect.x, obj.rect.y, obj.rect.width, obj.rect.height);
				cv::rectangle(frame, obj.rect, cv::Scalar(255, 0, 0));
				char text[256];
				//sprintf(text, "%s %.1f%%", class_names[obj.label], obj.prob * 100);
				sprintf(text, "%s", class_names[obj.label]);
				int baseLine = 0;
				cv::Size label_size = cv::getTextSize(text, cv::FONT_HERSHEY_SIMPLEX, 0.5, 1, &baseLine);
				int x = obj.rect.x;
				int y = obj.rect.y - label_size.height - baseLine;
				if (y < 0)
					y = 0;
				if (x + label_size.width > frame.cols)
					x = frame.cols - label_size.width;
				cv::rectangle(frame, cv::Rect(cv::Point(x, y), cv::Size(label_size.width, label_size.height + baseLine)),
					cv::Scalar(255, 255, 255), -1);
				cv::putText(frame, text, cv::Point(x, y + label_size.height),
					cv::FONT_HERSHEY_SIMPLEX, 0.5, cv::Scalar(0, 0, 0));
			}
			//cv::imwrite("./result20.jpg", image);
			cv::imshow("ss", frame);
			end2 = clock();
			float rumtime = (float)(end2 - start) / CLOCKS_PER_SEC;
			std::stringstream buf;
			buf.precision(3);//??????????
			buf.setf(std::ios::fixed);//????С??λ
			buf << rumtime;
			std::string strtime;
			strtime = buf.str();
			std::cout << "strtime2222 = " << strtime << std::endl;
			//start = end2;
			if (cv::waitKey(5) == 'q') {
				break;
			}
			mutexk.unlock();
		}
	}
	capture.release();
}
void get_camusb()
{
	//std::lock_guard<std::mutex> mtx_locker(mtx);
	clock_t start, end, end1, end2;
	//std::string rtsps = "rtsp://wowzaec2demo.streamlock.net/vod/mp4:BigBuckBunny_115k.mp4";
	std::string rtsps = "rtsp://admin:bs123456@192.168.1.64:554/h264/ch1/main/av_stream/1";
	VideoCaptureMT capture(rtsps);
	cv::Mat frameusb;
	cv::namedWindow("zz1", 0);
	while (capture.isOpened()) {
		std::lock_guard<std::mutex> mtx_locker1(mtx);
		start = clock();
		if (!capture.read(frameusb)) {
			break;
		}
		if (mutexk.try_lock()) {
			//gray = frame;
			end = clock();
			std::vector<Object> objectsusb;
			tmp->detect(frameusb, objectsusb);
			//tmp->draw_objects(frameusb, objectsusb);
			for (size_t i = 0; i < objectsusb.size(); i++)
			{
				const Object& obj = objectsusb[i];
				fprintf(stderr, "%d = %.5f at %.2f %.2f %.2f x %.2f\n", obj.label, obj.prob,
					obj.rect.x, obj.rect.y, obj.rect.width, obj.rect.height);
				cv::rectangle(frameusb, obj.rect, cv::Scalar(255, 0, 0));
				char text[256];
				//sprintf(text, "%s %.1f%%", class_names[obj.label], obj.prob * 100);
				sprintf(text, "%s", class_names[obj.label]);
				int baseLine = 0;
				cv::Size label_size = cv::getTextSize(text, cv::FONT_HERSHEY_SIMPLEX, 0.5, 1, &baseLine);
				int x = obj.rect.x;
				int y = obj.rect.y - label_size.height - baseLine;
				if (y < 0)
					y = 0;
				if (x + label_size.width > frameusb.cols)
					x = frameusb.cols - label_size.width;
				cv::rectangle(frameusb, cv::Rect(cv::Point(x, y), cv::Size(label_size.width, label_size.height + baseLine)),
					cv::Scalar(255, 255, 255), -1);
				cv::putText(frameusb, text, cv::Point(x, y + label_size.height),
					cv::FONT_HERSHEY_SIMPLEX, 0.5, cv::Scalar(0, 0, 0));
			}
			//cv::imwrite("./result20.jpg", image);
			cv::imshow("zz1", frameusb);
			end2 = clock();
			float rumtime = (float)(end2 - start) / CLOCKS_PER_SEC;
			std::stringstream buf;
			buf.precision(3);//??????????
			buf.setf(std::ios::fixed);//????С??λ
			buf << rumtime;
			std::string strtime;
			strtime = buf.str();
			std::cout << "strtime1111 = " << strtime << std::endl;
			//start = end2;
			if (cv::waitKey(5) == 'q') {
				break;
			}
			mutexk.unlock();
		}
	}
	capture.release();
}
int main() {
	void* p_algorithm;
	p_algorithm = (void*)(new WindNetDetect());
	std::string net_bins = "./models/visdrone_1009-opt.bin";
	std::string net_paras = "./models/visdrone_1009-opt.param";
	int init_res = ((WindNetDetect*)p_algorithm)->init1(net_bins, net_paras);
	tmp = (WindNetDetect*)(p_algorithm);
	std::thread thrd_1(get_cam1);
	std::thread thrd_2(get_camusb);
	thrd_1.join();
	thrd_2.join();
	while (true)
	{
		std::cout << "Main Thread Display!" << std::endl;
		Sleep(3000);
	}
	return 0;
}

使用多線線程調用多個函數同步執行模板如下：

#include <thread>
#include <mutex>
static std::mutex mutexk;
void func1() {
	while (capture1.isOpened()) {
		if (mutexk.try_lock()) {
			//我的算法
			my_func1();
            mutexk.unlock();
		}
	}
}
void func2() {
	while (capture2.isOpened()) {
		if (mutexk.try_lock()) {
			//我的算法
			my_func2();
            mutexk.unlock();
		}
	}
}
int main() {
	std::thread thrd_1(func1);
	std::thread thrd_2(func2);
	thrd_1.join();
	thrd_2.join();
	return 0;
}

在ubuntu中c++opencv多線程顯示圖片時出現Gdk-WARNING **: xx: Fatal IO error

解決辦法：

1、sudo apt install libx11-dev

2、在代碼中添加頭文件#include <X11/Xlib.h>

3、在創建線程之前添加XInitThreads()

4、在編譯的時候需要添加-lX11

參考鏈接：OpenCV視頻流C++多線程處理方法詳細分析

原文鏈接：https://blog.csdn.net/zk_ken/article/details/127802063

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