You need to check your frame is empty or not after each query Like frame=cvQueryFrame(capture); if (frame.empty()) break; You are getting such an error because you are trying to convert an empty Mat to grayscale after last frame, so exit the loop if frame is empty.
I made some modifications to the following 2 answers to make it compatible with Swift 5: https://stackoverflow.com/a/40354948/2470084 https://stackoverflow.com/a/39329155/2470084 import AVFoundation func encodeVideo(videoURL: URL){ let avAsset = AVURLAsset(url: videoURL) let startDate = Date() let exportSession = AVAssetExportSession(asset: avAsset, presetName: AVAssetExportPresetPassthrough) let docDir = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] let myDocPath = NSURL(fileURLWithPath: docDir).appendingPathComponent(“temp.mp4”)?.absoluteString let docDir2 = FileManager.default.urls(for: .documentDirectory, … Read more
Virtual webcam is typically a software only implementation that application discover as if it is a device with physical representation. The mentioned applications use APIs to work with web cameras and ability to extend the APIs and add your own video source is the way to create a virtual web camera. In Windows there are … Read more
Translated with some edits from: First frame of a video using AVFoundation var err: NSError? = nil let asset = AVURLAsset(URL: NSURL(fileURLWithPath: “/that/long/path”), options: nil) let imgGenerator = AVAssetImageGenerator(asset: asset) let cgImage = imgGenerator.copyCGImageAtTime(CMTimeMake(0, 1), actualTime: nil, error: &err) // !! check the error before proceeding let uiImage = UIImage(CGImage: cgImage) let imageView = UIImageView(image: … Read more
After some time I’ve found out that it is always only the first call of read that fails and skipping the first frame started to work fine although the true reason of this behavior remained unknown. Later James Barnett (see comments above) has pointed out that the reason might be that it takes a while … Read more
1- I have created a activity to start service like this: package com.android.camerarecorder; import android.app.Activity; import android.content.Intent; import android.hardware.Camera; import android.os.Bundle; import android.view.SurfaceHolder; import android.view.SurfaceView; import android.view.View; import android.widget.Button; public class CameraRecorder extends Activity implements SurfaceHolder.Callback { private static final String TAG = “Recorder”; public static SurfaceView mSurfaceView; public static SurfaceHolder mSurfaceHolder; public static Camera … Read more
You cannot simply use messaging the same way you would use it in a content script from an arbitrary webpage’s code. There are two guides available in the documentation for communicating with webpages, which correspond to two approaches: (externally_connectable) (custom events with a content script) Suppose you want to allow http://example.com to send a message … Read more
That’s a solution code I’ve written using @Raoul tips. I used PIL ImageGrab module to grab the printscreen frames. import numpy as np from PIL import ImageGrab import cv2 while(True): printscreen_pil = ImageGrab.grab() printscreen_numpy = np.array(printscreen_pil.getdata(),dtype=”uint8″)\ .reshape((printscreen_pil.size[1],printscreen_pil.size[0],3)) cv2.imshow(‘window’,printscreen_numpy) if cv2.waitKey(25) & 0xFF == ord(‘q’): cv2.destroyAllWindows() break
A missing OpenCV’s ffmpeg.dll does not generate any warnings/errors in OpenCV 2.3.1, and code fails silently. Make sure that you have proper opencv_ffmpeg*.dll in your path.
There isn’t any need for a third-party DLL. This simple method captures the current screen image into a .NET Bitmap object. private Image CaptureScreen() { Rectangle screenSize = Screen.PrimaryScreen.Bounds; Bitmap target = new Bitmap(screenSize.Width, screenSize.Height); using(Graphics g = Graphics.FromImage(target)) { g.CopyFromScreen(0, 0, 0, 0, new Size(screenSize.Width, screenSize.Height)); } return target; } I am sure you … Read more