From 90807cb6bca3093512a3e9ad78ac3f94fbb5ebf7 Mon Sep 17 00:00:00 2001
From: wangchunlin <wangchunin666@gmail.com>
Date: Wed, 6 Sep 2023 20:01:18 +0800
Subject: [PATCH] =?UTF-8?q?=E7=8E=B0=E5=9C=A8=E5=AD=98=E5=9C=A8=E6=AE=B5?=
 =?UTF-8?q?=E9=94=99=E8=AF=AF=EF=BC=8C=E4=BD=BF=E7=94=A8librt=E5=BA=93?=
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 =?UTF-8?q?mmap?=
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---
 receiver.cpp | 63 +++++++++++++++++++++++++++++++++++++++++++
 sender.cpp   | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 138 insertions(+)
 create mode 100644 receiver.cpp
 create mode 100644 sender.cpp

diff --git a/receiver.cpp b/receiver.cpp
new file mode 100644
index 0000000..c238500
--- /dev/null
+++ b/receiver.cpp
@@ -0,0 +1,63 @@
+#include <iostream>
+#include <opencv2/opencv.hpp>
+#include <sys/mman.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+int main() {
+    // 打开共享内存
+    int shmFd = shm_open("/video_shm", O_RDWR, 0666);
+    if (shmFd == -1) {
+        std::cerr << "Failed to open shared memory" << std::endl;
+        return 1;
+    }
+    void* sharedMemory = mmap(NULL, sizeof(int) * 3 + sizeof(double), PROT_READ | PROT_WRITE, MAP_SHARED, shmFd, 0);
+    if (sharedMemory == MAP_FAILED) {
+        std::cerr << "Failed to map shared memory" << std::endl;
+        return 1;
+    }
+
+    // 获取共享内存指针
+    char* dataPtr = static_cast<char*>(sharedMemory);
+
+    // 创建窗口用于显示视频
+    cv::namedWindow("Received Video", cv::WINDOW_NORMAL);
+
+    // 接收并实时播放视频帧
+    while (true) {
+        // 读取图像尺寸
+        int width = *reinterpret_cast<int*>(dataPtr);
+        dataPtr += sizeof(int);
+        int height = *reinterpret_cast<int*>(dataPtr);
+        dataPtr += sizeof(int);
+        int type = *reinterpret_cast<int*>(dataPtr);
+        dataPtr += sizeof(int);
+
+        // 计算图像数据的大小
+        size_t imageDataSize = width * height * CV_ELEM_SIZE(type);
+
+        // 创建图像矩阵
+        cv::Mat frame(height, width, type, reinterpret_cast<void*>(dataPtr));
+        dataPtr += imageDataSize;
+
+        // 读取帧率信息
+        double fps = *reinterpret_cast<double*>(dataPtr);
+        dataPtr += sizeof(double);
+
+        // 显示图像
+        cv::imshow("Received Video", frame);
+
+        // 打印帧率
+        std::cout << "Received FPS: " << fps << std::endl;
+
+        // 按下 ESC 键退出循环
+        if (cv::waitKey(1) == 27)
+            break;
+    }
+
+    // 关闭共享内存
+    munmap(sharedMemory, sizeof(int) * 3 + sizeof(double));
+    close(shmFd);
+
+    return 0;
+}
diff --git a/sender.cpp b/sender.cpp
new file mode 100644
index 0000000..00bcd7f
--- /dev/null
+++ b/sender.cpp
@@ -0,0 +1,75 @@
+#include <iostream>
+#include <opencv2/opencv.hpp>
+#include <sys/mman.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+int main() {
+    // 打开视频文件
+    cv::VideoCapture cap("1.mp4");
+    if (!cap.isOpened()) {
+        std::cerr << "Failed to open video file" << std::endl;
+        return 1;
+    }
+
+    // 获取视频帧率
+    double fps = cap.get(cv::CAP_PROP_FPS);
+    std::cout << "Original FPS: " << fps << std::endl;
+
+    // 获取图像尺寸
+    int width = cap.get(cv::CAP_PROP_FRAME_WIDTH);
+    int height = cap.get(cv::CAP_PROP_FRAME_HEIGHT);
+    int type = CV_8UC3;  // 假设图像类型为 8 位 3 通道彩色图像
+
+    // 计算图像数据的大小
+    size_t imageDataSize = width * height * CV_ELEM_SIZE(type);
+
+    // 创建共享内存
+    int shmFd = shm_open("/video_shm", O_CREAT | O_RDWR, 0666);
+    if (shmFd == -1) {
+        std::cerr << "Failed to create shared memory" << std::endl;
+        return 1;
+    }
+    size_t shmSize = sizeof(int) * 3 + imageDataSize + sizeof(double);  // 计算共享内存大小
+    ftruncate(shmFd, shmSize);
+    void* sharedMemory = mmap(NULL, shmSize, PROT_READ | PROT_WRITE, MAP_SHARED, shmFd, 0);
+    if (sharedMemory == MAP_FAILED) {
+        std::cerr << "Failed to map shared memory" << std::endl;
+        return 1;
+    }
+
+    // 获取共享内存指针
+    char* dataPtr = static_cast<char*>(sharedMemory);
+
+    // 逐帧读取并发送
+    cv::Mat frame;
+    while (cap.read(frame)) {
+        // 将图像尺寸复制到共享内存
+        memcpy(dataPtr, &width, sizeof(int));
+        dataPtr += sizeof(int);
+        memcpy(dataPtr, &height, sizeof(int));
+        dataPtr += sizeof(int);
+        memcpy(dataPtr, &type, sizeof(int));
+        dataPtr += sizeof(int);
+
+        // 将图像数据复制到共享内存
+        memcpy(dataPtr, frame.data, imageDataSize);
+        dataPtr += imageDataSize;
+
+        // 将帧率信息复制到共享内存
+        memcpy(dataPtr, &fps, sizeof(double));
+
+        // 等待接收方读取共享内存
+        usleep(1000);
+
+        // 打印帧率
+        std::cout << "Sent FPS: " << fps << std::endl;
+    }
+
+    // 关闭共享内存
+    munmap(sharedMemory, shmSize);
+    close(shmFd);
+    shm_unlink("/video_shm");
+
+    return 0;
+}