使用OpenCV从.avi视频获取帧 [英] Getting frames from .avi video using OpenCV
问题描述
#include "cv.h"
#include "highgui.h"
int main(int argc, char** argv)
{
CvCapture* capture=0;
IplImage* frame=0;
capture = cvCaptureFromAVI("C:\\boy walking back.avi"); // read AVI video
if( !capture )
throw "Error when reading steam_avi";
cvNamedWindow( "w", 1);
for( ; ; )
{
/* int cvGrabFrame (CvCapture* capture);
IplImage* cvRetrieveFrame (CvCapture* capture)*/
frame = cvQueryFrame( capture );
if(!frame)
break;
cvShowImage("w", frame);
}
cvWaitKey(0); // key press to close window
cvDestroyWindow("w");
cvReleaseImage(&frame);
}
我正在将openCV与VS2008一起使用.我已经读了一个视频文件,并使用CV_CAP_PROP_FRAME_COUNT来获取帧数,对于4秒长的视频剪辑,该帧数约为130.我正在对行走进行运动识别,因此我需要每隔5帧获得一次,因为在5帧之间,身体的运动几乎没有变化.到目前为止,我有一个程序可以让我获取视频剪辑的一帧.但是,我无法获得不同的帧,而且我不确定如何获取其他5帧.上面是用于获取视频一帧的代码.
I am using openCV with VS2008. I have read in a video file and used CV_CAP_PROP_FRAME_COUNT to obtain the number of frames which was approximately 130 for a 4 second long video clip. I am doing a motion recognition of walking so I need to get every other 5 frames since between 5 frames, there is little change in the motion of the body. I have a program so far which allows me to obtain one frame of the video clip. However, I am unable to obtain different frames and also, I am not sure how to go about getting every other 5 frames. The above is the code used to get one frame of the video.
推荐答案
您应该可以跳过4帧,然后保持第5帧.下面是我写的一个小例子来演示这一点:
You should be able to skip 4 frames, and then keep the 5th frame. Below is a small example I wrote to demonstrate this:
IplImage* skipNFrames(CvCapture* capture, int n)
{
for(int i = 0; i < n; ++i)
{
if(cvQueryFrame(capture) == NULL)
{
return NULL;
}
}
return cvQueryFrame(capture);
}
int main(int argc, char* argv[])
{
CvCapture* capture = cvCaptureFromFile("../opencv-root/samples/c/tree.avi");
IplImage* frame = NULL;
do
{
frame = skipNFrames(capture, 4);
cvNamedWindow("frame", CV_WINDOW_AUTOSIZE);
cvShowImage("frame", frame);
cvWaitKey(100);
} while( frame != NULL );
cvReleaseCapture(&capture);
cvDestroyWindow("frame");
cvReleaseImage(&frame);
return 0;
}
希望有帮助:)
这篇关于使用OpenCV从.avi视频获取帧的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!