使用opencv：从视频中获取每一帧图片

使用opencv：从视频中获取每一帧图片

★ C实现

当前目录：~/test/opencv/getframe，在此目录中创建getframe.cpp和CMakeLists.txt

• getframe.cpp

#include <stdio.h>#include <opencv2/opencv.hpp>#include <sys/stat.h>#include <sys/types.h>#include <sys/stat.h>#include <unistd.h>#include <errno.h>using namespace cv;int main(int argc, char** argv ) {    if ( argc != 2 ) {        printf("usage: ./getframe <Video_Path>\n");        return -1;    }    CvCapture* cvCap = cvCaptureFromFile(argv[1]);// argv[1] is video name    const char *winName = "Show Frames";    cvNamedWindow(winName,CV_WINDOW_AUTOSIZE);    // output directory    char dirName[512] = {0};    char *p = strrchr(argv[1], '/');    strcpy(dirName, p+1);    p = strchr(dirName, '.');    *p = '_';    printf("output dir: %s\n", dirName);    struct stat dirInfo = {0};    int statRet = stat(dirName, &dirInfo);    if (statRet == -1 && errno == ENOENT) {        int ret = mkdir(dirName, 0775);        if (ret == 0) {            printf("mkdir success: %s\n", dirName);        } else {            printf("mkdir failed: %s\n", dirName);            return -1;        }    }    printf("press any key to stop.\n");     int id = 1;    while(1) {        IplImage* img = cvQueryFrame(cvCap);        if (img == NULL) {            printf("No more frames, press any key to exit.\n");            break;        }        cvShowImage(winName, img);        char name[512] = {0};        sprintf(name, "./%s/%04d.jpg", dirName, id);        cvSaveImage(name, img);        id++;        int key = cvWaitKey(1000/33);// 30 frame/second for displaying in window    }    cvReleaseCapture(&cvCap);    waitKey(0);    cvDestroyWindow(winName);    return 0;}

• CMakeLists.txt

cmake_minimum_required(VERSION 2.8)project( getframe )find_package( OpenCV REQUIRED )add_executable( getframe getframe.cpp )target_link_libraries( getframe ${OpenCV_LIBS} )

编译：（当前目录：~/test/opencv/getframe）

mkdir buildcd buildcmake ..make

生成getframe可执行程序。

运行：

./getframe ../Megamind.avi

在build目录中的Megamind_avi目录中是获取的视频的每一帧图片。

★ C++实现

#include <stdio.h>#include <opencv2/opencv.hpp>#include <sys/stat.h>#include <sys/types.h>#include <sys/stat.h>#include <unistd.h>#include <errno.h>using namespace cv;int main(int argc, char** argv ) {    if ( argc != 2 ) {        printf("usage: getframe <Video_Path>\n");        return -1;    }    VideoCapture cap(argv[1]);    if(!cap.isOpened()) {        printf("video is not ready\n");        return -1;    }    // output directory    char dirName[512] = {0};    char *p = strrchr(argv[1], '/');    strcpy(dirName, p+1);    p = strchr(dirName, '.');    *p = '_';    printf("output dir: %s\n", dirName);    struct stat dirInfo = {0};    int statRet = stat(dirName, &dirInfo);    if (statRet == -1 && errno == ENOENT) {        int ret = mkdir(dirName, 0775);        if (ret == 0) {            printf("mkdir success: %s\n", dirName);        } else {            printf("mkdir failed: %s\n", dirName);            return -1;         }    }       printf("press any key to stop.\n");    const char *winName = "Show Frames";    namedWindow(winName, 1);    Mat frame;    int id = 1;    while(1) {        cap.grab();        if (!cap.retrieve(frame)) {            printf("No more frames, press any key to exit.\n");            break;        }        char name[512] = {0};        sprintf(name, "%s/%04d.jpg", dirName, id);        imshow(winName, frame);        imwrite(name, frame);        id++;        if(waitKey(30) >= 0) break;    }    cap.release();    waitKey(0);    cvDestroyWindow(winName);    return 0;}

★ 参考

https://docs.opencv.org/2.4/modules/highgui/doc/reading_and_writing_images_and_video.html

python版的，可以参考：
https://docs.opencv.org/3.0-beta/doc/py_tutorials/py_gui/py_video_display/py_video_display.html