我一直在使用OpenCV 2.4.3将一些视频处理代码移植到C ++。以下测试程序非常模仿我的代码如何从视频中读取每个帧,对其内容进行操作,然后将新帧写入新的视频文件。
奇怪的是,单独设置像素时输出帧完全是黑色,但克隆整个帧时 正确写入。
实际上,我会使用这两个宏来访问和分配所需的值,但示例中使用的顺序扫描更清楚地显示了这个想法。
有谁知道我哪里出错了?
test.cpp
:
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <iostream>
#include <string>
using namespace std;
using namespace cv;
#define RGB_REF(PR,NC,R,C,CH) (*((PR) + ((3*(NC)*(R)+(C))+(CH))))
#define GRAY_REF(PR,NC,R,C) (*((PR) + (NC)*(R)+(C)))
int main(int argc, char* argv[])
{
string video_path(argv[1]);
cerr << "Video path is " + video_path + "\n";
VideoCapture capture(video_path);
if ( !capture.isOpened() )
{
cerr << "Input file could not be opened\n";
return 1;
} else
{
string output_path(argv[2]);
VideoWriter output;
int ex = (int)capture.get(CV_CAP_PROP_FOURCC);
Size S = Size((int) capture.get(CV_CAP_PROP_FRAME_WIDTH),
(int) capture.get(CV_CAP_PROP_FRAME_HEIGHT));
output.open(output_path,ex,capture.get(CV_CAP_PROP_FPS),S,true);
if ( !output.isOpened() )
{
cerr << "Output file could not be opened\n";
return 1;
}
unsigned int numFrames = (unsigned int) capture.get(CV_CAP_PROP_FRAME_COUNT);
unsigned int m = (unsigned int) capture.get(CV_CAP_PROP_FRAME_HEIGHT);
unsigned int n = (unsigned int) capture.get(CV_CAP_PROP_FRAME_WIDTH);
unsigned char* im = (unsigned char*) malloc(m*n*3*sizeof(unsigned char));
unsigned char* bw = (unsigned char*) malloc(m*n*3*sizeof(unsigned char));
Mat frame(m,n,CV_8UC3,im);
Mat outputFrame(m,n,CV_8UC3,bw);
for (size_t i=0; i<numFrames; i++)
{
capture >> frame;
for (size_t x=0;x<(3*m*n);x++)
{
bw[x] = im[x];
}
output << outputFrame; // blank frames
// output << frame; // works
// output << (outputFrame = frame); // works
}
}
}
答案 0 :(得分:1)
当您从VideoCapture查询框架为capture >> frame;
时,frame
会被修改。比如,它有一个新的数据缓冲区。因此im
不再指向frame
的缓冲区
尝试
bm[x] = frame.ptr()[x];