2.2播放 AVI 视频

#include "highgui.h"

int main( int argc, char** argv ) { 
	cvNamedWindow( "Example2", CV_WINDOW_AUTOSIZE );
	//CvCapture* capture = cvCaptureFromAVI( argv[1] ); // either one will work
	CvCapture* capture = cvCreateFileCapture("D:\\tree.avi");    //tree.avi的路径如下图
	IplImage* frame;
	while(1) {
		frame = cvQueryFrame( capture );
		if( !frame ) break;
		cvShowImage( "Example2", frame );
		char c = cvWaitKey(33);
		if( c == 27 ) break;
	}
	cvReleaseCapture( &capture );
	cvDestroyWindow( "Example2" );
}

2.3视频播放控制--添加滚动条

#include <stdio.h>
#include <iostream>
#include <fstream>
#include "cv.h"
#include "highgui.h"

using namespace std;

int        g_slider_position = 0;
CvCapture* g_capture         = NULL;

void onTrackbarSlide(int pos) {
	cvSetCaptureProperty(
		g_capture,
		CV_CAP_PROP_POS_FRAMES,
		pos
		);
}

//Hack because sometimes the number of frames in a video is not accessible. 
//Probably delete this on Widows
int getAVIFrames(char * fname) { 
	char tempSize[4];
	// Trying to open the video file
	ifstream  videoFile( fname , ios::in | ios::binary );
	// Checking the availablity of the file
	if ( !videoFile ) {
		cout << "Couldn’t open the input file " << fname << endl;
		exit( 1 );
	}
	// get the number of frames
	videoFile.seekg( 0x30 , ios::beg );
	videoFile.read( tempSize , 4 );
	int frames = (unsigned char ) tempSize[0] + 0x100*(unsigned char ) tempSize[1] + 0x10000*(unsigned char ) tempSize[2] +    0x1000000*(unsigned char ) tempSize[3];
	videoFile.close(  );
	return frames;
}


int main( int argc, char** argv ) {
	cvNamedWindow( "Example2_3", CV_WINDOW_AUTOSIZE );
	g_capture = cvCreateFileCapture("D:\\tree.avi");
	IplImage *foo = cvQueryFrame( g_capture);


	int frames = (int) cvGetCaptureProperty(
		g_capture,
		CV_CAP_PROP_FRAME_COUNT
		);

	int tmpw = (int) cvGetCaptureProperty(
		g_capture,
		CV_CAP_PROP_FRAME_WIDTH
		);

	int tmph = (int) cvGetCaptureProperty(
		g_capture,
		CV_CAP_PROP_FRAME_HEIGHT
		);

	printf("opencv frames %d w %d h %d\n",frames,tmpw,tmph);

	frames = getAVIFrames(argv[1]); //This is a hack because on linux, getting number of frames often doesn't work

	printf("hacked frames %d w %d h %d\n",frames,tmpw,tmph);

	cvCreateTrackbar(
		"Position",
		"Example2_3",
		&g_slider_position,
		frames,
		onTrackbarSlide
		);
	IplImage* frame;
	frames = 0;
	while(1) {
		frame = cvQueryFrame( g_capture );
		if( !frame ) break;
		//      int frames = cvGetCaptureProperty( g_capture, CV_CAP_PROP_POS_FRAMES);//This should work, sometimes it does not on linux
		frames++; //My cheat
		printf("\nFrame number=%d\n",frames);
		cvSetTrackbarPos("Position","Example2_3",frames);
		cvShowImage( "Example2_3", frame );
		char c = (char)cvWaitKey(10);
		if( c == 27 ) break;
	}
	cvReleaseCapture( &g_capture );
	cvDestroyWindow( "Example2_3" );
	return(0);
}