Video files in opencv

Question

I want to read video file(.avi or .mov) and detect motion and edges using Opencv.Can u help me with code?I want to create a GUI in which we can select the video file,then we can carry out image processing functions in opencv?

bro, its not going to be easy. You will still need to learn the basics yourself. — , Mar 30 '12 at 10:50
http://www.laganiere.name/opencvCookbook/ Check this book. Simple and concise and will help you getting started with OpenCV — , Mar 30 '12 at 10:51

score 12 · Answer 1 · edited May 23 '17 at 11:43

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How to read a video file:

Read video file and display it on a window (C API)
Read video file and display it on a window (C++ API)
Read video file, convert it to grayscale then display it on a window (C API)

How to track/detect motion:

How to detect edges/countours:

And for more info on how to detect shapes, check this post.

edited May 23 '17 at 11:43

Community

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answered Mar 30 '12 at 13:48

karlphillip

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You rock, do you have some kind of database of computer vision FAQ's? :P – Rui Marques Jul 04 '12 at 09:32

score 2 · Answer 2 · edited May 23 '17 at 11:58

This works for me, I'm using AVIfiles. Call video withe filename, in your main-loop get the next frame and shutdown before terminating or changing to another video.

IplImage  *videoframe;
int videoFps;    
CvCapture *videoCapture=NULL;

int video(char *videoFile) {
    int       key;
    /* load the AVI file */
    videoCapture = cvCaptureFromAVI( videoFile );
    /* always check */
    if( !videoCapture )
        return 0;    
    /* get fps, needed to set the delay */
    videoFps = ( int )cvGetCaptureProperty( videoCapture, CV_CAP_PROP_FPS );
    /* display video */
    cvNamedWindow( "video", 0 );
}

void videoNext() {
        if ( ! videoCapture ) return;
        videoframe = cvQueryFrame( videoCapture );
        if( !videoframe ) return;
        cvShowImage( "video", videoframe );
        /* quit if user press 'q' */
        int key = cvWaitKey( 1000 / videoFps );
}

void videoShutdown() {
    /* free memory */
    cvReleaseCapture( &videoCapture );
    cvDestroyWindow( "video" );
    return;
}

Note: Opencv doesn't support audio playback On how to use ffmmpeg with opencv see audio-output-with-video-processing-with-opencv

score 1 · Answer 3 · answered Apr 04 '12 at 22:37

You should look at the samples included in the python folder for opencv. They will be found here: opencv\samples\python2

There you will find many of the basic and advanced features of opencv (in the cv2 format) demonstrated. There are also many tutorials (mainly in c++) on the website here: http://opencv.itseez.com/doc/tutorials/tutorials.html

Reading and writing video images is here: http://opencv.itseez.com/trunk/modules/highgui/doc/reading_and_writing_images_and_video.html

For initial video capture from AVI:

import cv2
import cv2.cv as cv
import numpy as np

cap = cv2.VideoCapture(filename)
img = cv2.VideoCapture.read()
if img:
   print img.get(cv.CV_CAP_PROP_FRAME_HEIGHT)
   print type(img)
# loop through rest of frames reading one at a time

Are you sure about that code? According to the doc, `cv2.VideoCapture.read()` returns a tuple: RetVal, Image. — LarsH, Sep 26 '13 at 13:50

score 1 · Answer 4 · answered Mar 30 '12 at 06:25

1

The shortest example for reading a frame from a video :

cap = cv::VideoCapture("foo.avi");
frame = cv::Mat;
cap >> frame;

answered Mar 30 '12 at 06:25

Herr von Wurst

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Video files in opencv

4 Answers4

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