c++ - opencv 将网络摄像头输出写入 avi 文件

Question

我正在尝试使用 opencv 从我的网络摄像头输出创建一个 avi 视频。没有抛出异常，但是它创建的 avi 文件大小为 414 字节并且不会增长。

它也不会与任何媒体播放器一起播放。我怀疑写入文件部分有问题。

代码如下:

  CvCapture *capture = cvCaptureFromCAM( 0 );

  int width = ( int )cvGetCaptureProperty( capture, 
  CV_CAP_PROP_FRAME_WIDTH );

  int height = ( int )cvGetCaptureProperty( capture,
  CV_CAP_PROP_FRAME_HEIGHT );
  CvVideoWriter *writer = cvCreateVideoWriter("CamCapture.avi",                                                     
  -1,30, cvSize(  width, height ) );

  cvNamedWindow("capWindow", CV_WINDOW_AUTOSIZE);
  IplImage *frame = 0;

  // this returns 0 not sure why ??
  //double fps = cvGetCaptureProperty(capture, CV_CAP_PROP_FPS);
  double fps = 30;

  while( 1 )
  {
      frame = cvQueryFrame( capture );
      cvShowImage("capWindow",frame);
      cvWriteFrame( writer, frame );
      char c = cvWaitKey(1000/fps);

      if( c == 27 ) break;
  }

   cvReleaseCapture( &capture );
   cvReleaseVideoWriter( &writer );
   cvDestroyWindow( "capWindow" );

我引用并尝试了以下示例，但没有成功:

• http://gipetrou.com/scc/2010/12/12/save-video-from-webcam-with-opencv-2-1/
• http://answers.oreilly.com/topic/1366-how-to-write-to-an-avi-file-with-opencv/
• https://www.cs.utexas.edu/~teammco/misc/udp_video/

Answer 1

不要用过时的C，用C++的api，简单易用，比如上面的代码可以用C++改写，

#include "opencv2/opencv.hpp"
#include <iostream>

using namespace std;
using namespace cv;

int main(){

    VideoCapture vcap(0); 
      if(!vcap.isOpened()){
             cout << "Error opening video stream or file" << endl;
             return -1;
      }

   int frame_width=   vcap.get(CV_CAP_PROP_FRAME_WIDTH);
   int frame_height=   vcap.get(CV_CAP_PROP_FRAME_HEIGHT);
   VideoWriter video("out.avi",CV_FOURCC('M','J','P','G'),10, Size(frame_width,frame_height),true);

   for(;;){

       Mat frame;
       vcap >> frame;
       video.write(frame);
       imshow( "Frame", frame );
       char c = (char)waitKey(33);
       if( c == 27 ) break;
    }
  return 0;
}