使用 OpenCV 的 GPU 模块，使用独立显卡对视频处理进行加速

1.使用 CPU 进行处理

#include <stdio.h>
#include <stdlib.h>
#include <iostream>

#include <opencv2/opencv.hpp>
#include <opencv2/core/cuda.hpp>
#include <opencv2/imgproc/types_c.h>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include "cuda_runtime.h"
#include "device_launch_parameters.h"

using namespace std;
using namespace cv;
using namespace cuda;

/* 调用OpenCV直方图均衡函数 */
Mat equalizeHist_OpenCVGray(Mat& matSrc) {
    Mat matArray;
    cv::cvtColor(matSrc, matSrc, CV_BGR2GRAY);

    Mat dst;
    cv::equalizeHist(matSrc, dst);
    return dst;
}

Mat equalizeHist_OpenCVRGB(Mat& matSrc)
{
    Mat matArray[3];
    split(matSrc, matArray);
    // 直方图均衡化
    for (int i = 0; i < 3; i++)
        cv::equalizeHist(matArray[i], matArray[i]);
    Mat dst;
    merge(matArray, 3, dst);
    return dst;
}

int main() {
    
    VideoCapture capturer("C:/Users/76371/Desktop/parking.mp4");

    if (!capturer.isOpened()) {
        cerr << "Open video failed!" << endl;
        return false;
    }
    
    int fps = capturer.get(CV_CAP_PROP_FPS);
    int width = capturer.get(CV_CAP_PROP_FRAME_WIDTH);
    int height = capturer.get(CV_CAP_PROP_FRAME_HEIGHT);
    int frames = capturer.get(CV_CAP_PROP_FRAME_COUNT);

    cout << "FPS:" << fps << endl;
    cout << "Width:" << width << endl;
    cout << "Height:" << height << endl;
    cout << "Total frames:" << frames << endl;

    VideoWriter writer("C:/Users/76371/Desktop/parking_output.mp4", -1, fps, Size(width, height), false);
    double startTime, endTime;
    Mat frame, output;
    
    startTime = getTickCount();

    while (capturer.read(frame)) {
        output = equalizeHist_OpenCVRGB(frame);
        writer.write(output);
    }

    endTime = getTickCount();

    double duration = (endTime - startTime) / getTickFrequency();

    cout << "Duration:" << duration << "s" << endl;
    cout << "Average:" << duration / (double)(frames) * 1000 << "ms" << endl;
    
    capturer.release();
    writer.release();

    return 0;
}

2.使用 GPU 进行处理

#include <stdio.h>
#include <stdlib.h>
#include <iostream>

#include <opencv2/opencv.hpp>
#include <opencv2/core/cuda.hpp>
#include <opencv2/imgproc/types_c.h>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include "cuda_runtime.h"
#include "device_launch_parameters.h"

using namespace std;
using namespace cv;
using namespace cuda;

GpuMat GPU_equalizeHist_OpenCVGray(GpuMat& matSrc) {
    GpuMat matArray;
    cuda::cvtColor(matSrc, matSrc, CV_BGR2GRAY);

    GpuMat dst;
    cuda::equalizeHist(matSrc, dst);
    return dst;
}

GpuMat GPU_equalizeHist_OpenCVRGB(GpuMat& matSrc)
{
    static GpuMat matArray[3];
    cuda::split(matSrc, matArray);

    for (int i = 0; i < 3; i++)
        cuda::equalizeHist(matArray[i], matArray[i]);
    static GpuMat dst;
    merge(matArray, 3, dst);
    return dst;
}

int main() {
    
    /* 检查设定设备 */

    int num_devices = getCudaEnabledDeviceCount();

    if (num_devices <= 0) {
        cerr << "No device detected!" << endl;
        return -1;
    }

    int enable_device_id = -1;
    for (int i = 0; i < num_devices; i++) {
        DeviceInfo dev_info(i);
        if (dev_info.isCompatible())
            enable_device_id = i;
    }

    if (enable_device_id < 0) {
        cerr << "GPU module incompatible!" << endl;
        return -1;
    }

    setDevice(enable_device_id);

    /* 读入视频数据 */

    VideoCapture capturer("C:/Users/76371/Desktop/parking.mp4");

    if (!capturer.isOpened()) {
        cerr << "Open video failed!" << endl;
        return false;
    }

    int fps = capturer.get(CV_CAP_PROP_FPS);
    int width = capturer.get(CV_CAP_PROP_FRAME_WIDTH);
    int height = capturer.get(CV_CAP_PROP_FRAME_HEIGHT);
    int frames = capturer.get(CV_CAP_PROP_FRAME_COUNT);

    cout << "FPS:" << fps << endl;
    cout << "Width:" << width << endl;
    cout << "Height:" << height << endl;
    cout << "Total frames:" << frames << endl;

    /* 初始化 */
    VideoWriter writer("C:/Users/76371/Desktop/parking_output.mp4", -1, fps, Size(width, height), false);
    double startTime, endTime;

    static Mat frame(Size(width, height), CV_8UC3, Scalar(0, 0, 0));
    static GpuMat d_frame(frame), d_dst(Size(width, height), CV_8UC1, Scalar(0)), matArray[3];
    
    cuda::equalizeHist(d_dst, d_dst);
    cuda::split(d_frame, matArray);
    cuda::merge(matArray, 3, d_dst);

    /* 直方图均衡 */

    startTime = getTickCount();

    while (capturer.read(d_frame)) {
        d_dst = GPU_equalizeHist_OpenCVRGB(d_frame);
        d_dst.download(frame);
        writer.write(frame);
    }
    
    endTime = getTickCount();

    double duration = (endTime - startTime) / getTickFrequency();

    cout << "Duration:" << duration << "s" << endl;
    cout << "Average:" << duration / (double)(frames) * 1000 << "ms" << endl;

    capturer.release();
    writer.release();

    return 0;
}