Mat* _frame = new Mat(frameSize, CV_8UC3) //3 chanels, 8 bit per chanel VideoWriter* _recorder = new VideoWriter(name.toStdString(), -1, 20, frameSize, true) initialization : StartVideoFile(QString name, int width, int height) Unsigned char* frame = raw RGB data, coming directly from IP camera it is extraction of 3 functions QString name = "File full path" Here you can see simplification of my code. It is catched somewhere and i don't see it when executing app outside visual studio. It is real time fail proof application: no frames should be missed. I found some articles, what i can not use it. Can i "bring" codec with me in the file(dll)? Yes, i am developing in Windows, but app CAN (have to) work in Linux. For example, app will have a list of preferences and automatically select codec to use. i just need to know "codec is available" "programmatically" to chose one. OpenCV doesn't have a function to get the list of available codecs.īut how window with list of codecs (if you use -1 ) is working in this case?īut, it's really useful to programmatically get this list or you just need to know if a codec is available or to know its fourcc ?īoth. File size is 0 byte.įirst of all thank you for such detailed answer. By the way, what is the codes of this codecs?īy "not working" i mean file is created, but frames are not recorded by write() function. If i am passing (-1), i have this codecs in drop down.īut even not all of them are not working. the same with ('D', 'I', 'B', ' ')Ĭan you point me to list of codecs and\or how to get it from system.Īll i found for the moment is this, but not all seems to work for me:īasically, I need all allowed parameters for fourcc() function. When i am using (int)1 as a paremeter for VideoWriter.open(.) i have an exception, but after pressing "continue" video is recorded. I need to have an option: compression or not compressed. I need to grab images from camera and wright them in AVI file. The below code captures from a camera, flips every frame in the vertical direction, and saves the video.I am trying to run OpenCV for the first time. In OSX: MJPG (.mp4), DIVX (.avi), X264 (.mkv).įourCC code is passed as `cv.VideoWriter_fourcc('M','J','P','G') or cv.VideoWriter_fourcc(*'MJPG')` for MJPG.In Windows: DIVX (More to be tested and added).In Fedora: DIVX, XVID, MJPG, X264, WMV1, WMV2.The list of available codes can be found in. If it is True, the encoder expect color frame, otherwise it works with grayscale frame.įourCC is a 4-byte code used to specify the video codec. Then number of frames per second (fps) and frame size should be passed. Then we should specify the FourCC code (details in next paragraph). We should specify the output file name (eg: output.avi). This time we create a VideoWriter object. For images, it is very simple: just use cv.imwrite(). So we capture a video and process it frame-by-frame, and we want to save that video. Sometimes it is a headache to work with video capture, mostly due to wrong installation of ffmpeg/gstreamer. 25 milliseconds will be OK in normal cases.Ĭv.destroyAllWindows() Note Make sure a proper version of ffmpeg or gstreamer is installed. If it is too less, video will be very fast and if it is too high, video will be slow (Well, that is how you can display videos in slow motion). Also while displaying the frame, use appropriate time for cv.waitKey(). Playing video from file is the same as capturing it from camera, just change the camera index to a video file name. Note If you are getting an error, make sure your camera is working fine using any other camera application (like Cheese in Linux). Just use ret = cap.set( cv.CAP_PROP_FRAME_WIDTH,320) and ret = cap.set( cv.CAP_PROP_FRAME_HEIGHT,240). Value is the new value you want.įor example, I can check the frame width and height by cap.get( cv.CAP_PROP_FRAME_WIDTH) and cap.get( cv.CAP_PROP_FRAME_HEIGHT). Some of these values can be modified using cap.set(propId, value). Full details can be seen here: cv::VideoCapture::get(). Each number denotes a property of the video (if it is applicable to that video). You can also access some of the features of this video using cap.get(propId) method where propId is a number from 0 to 18. You can check whether it is initialized or not by the method cap.isOpened(). Sometimes, cap may not have initialized the capture. So you can check for the end of the video by checking this returned value. If the frame is read correctly, it will be True. Cap.read() returns a bool ( True/ False).
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