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POMemory leaks getting sub-images from video (cvGetSubRect)
 

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  1. POMemory leaks getting sub-images from video (cvGetSubRect)
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    <p>i'm trying to do video windowing that is: </p> <p>show all frames from a video and also some sub-image from each frame. This sub-image can change size and be taken from a different position of the original frame.</p> <p>So , the code i've written does basically this:</p> <ol> <li><strong>cvQueryFrame</strong> to get a new image from the video</li> <li>Create a new <strong>IplImage</strong> (img) with sub-image dimensions ( window.height,window.width)</li> <li>Create a new <strong>Cvmat</strong> (mat) with sub-image dimensions ( window.height,window.width)</li> <li><strong>CvGetSubRect</strong>(originalImage,mat,window) seizes the sub-image</li> <li>transform Mat (cvMat) to img (IplImage) using <strong>cvGetImage</strong></li> </ol> <p>my problem is that for each frame i create new IplImage and cvMat which take a lot of memory and when i try to free the allocated memory I get a segmentation fault or in the case of the CvMat the allocated space does not get free (valgrind keeps telling me its definetly lost space).</p> <p>the following code does it:</p> <pre><code>int main(void){ CvCapture* capture; CvRect window; CvMat * tmp; //window size window.x=0;window.y=0;window.height=100;window.width=100; IplImage * src=NULL,*bk=NULL,* sub=NULL; capture=cvCreateFileCapture( "somevideo.wmv"); while((src=cvQueryFrame(capture))!=NULL){ cvShowImage("common",src); //get sub-image sub=cvCreateImage(cvSize(window.height,window.width),8,3); tmp =cvCreateMat(window.height, window.width,CV_8UC1); cvGetSubRect(src, tmp , window); sub=cvGetImage(tmp, sub); cvShowImage("Window",sub); //free space if(bk!=NULL) cvReleaseImage(&amp;bk); bk=sub; cvReleaseMat(&amp;tmp); cvWaitKey(20); //window dimensions changes window.width++; window.height++; } } </code></pre> <p><strong>cvReleaseMat(&amp;tmp)</strong>; does not seem to have any effect on the total amount of lost memory, valgrind reports the same amount of "definetly lost" memory if i comment or uncomment this line. </p> <p><strong>cvReleaseImage(&amp;bk);</strong> produces a segmentation fault. notice i'm trying to free the previous sub-frame which i'm backing up in the bk variable. If i comment this line the program runs smoothly but with lots of memory leaks</p> <p>i'm using ubuntu 9.10 with opencv 2.0 .</p> <p>I really need to get rid of memory leaks, can anyone explain me how to correct this or even better how to correctly perform image windowing? </p> <p>Thank you </p>
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