専門ユニット2/山内研セミナー(2021/11/17)

関連サイトと資料

プロジェクトCameo

managers.py
import cv2
import numpy
import time
  
class CaptureManager(object):
    def __init__(self, capture, previewWindowManager = None, shouldMirrorPreview = False):
        self.previewWindowManager = previewWindowManager
        self.shouldMirrorPreview = shouldMirrorPreview
  
        self._capture = capture
        self._channel = 0
        self._enteredFrame = False
        self._frame = None
        self._imageFilename = None
        self._videoFilename = None
        self._videoEncoding = None
        self._videoWriter = None
  
        self._startTime = None
        self._framesElapsed = 0
        self._fpsEstimate = None
  
    @property
    def channel(self):
        return self._channel
  
    @channel.setter
    def channel(self, value):
        if self._channel != value:
            self._channel = value
            self._frame = None
  
    @property
    def frame(self):
        if self._enteredFrame and self._frame is None:
            _, self._frame = self._capture.retrieve(self._frame, self.channel)
        return self._frame
  
    @property
    def isWritingImage(self):
        return self._imageFilename is not None
  
    @property
    def isWritingVideo(self):
        return self._videoFilename is not None
  
    def enterFrame(self):
        """Capture the next frame, if any."""
  
        # But first, check that any previous frame was exited.
        assert not self._enteredFrame, 'previous enterFrame() had no matching exitFrame()'
  
        if self._capture is not None:
            self._enteredFrame = self._capture.grab()
  
    def exitFrame(self):
        """Draw to the window. Write to files. Release the frame."""
  
        # Check whether any grabbed frame is retrievable.
        # The getter may retrieve and cache the frame.
        if self.frame is None:
            self._enteredFrame = False
            return
  
        # Update the FPS estimate and related variables.
        if self._framesElapsed == 0:
            self._startTime = time.time()
        else:
            timeElapsed = time.time() - self._startTime
            self._fpsEstimate =  self._framesElapsed / timeElapsed
        self._framesElapsed += 1
  
        # Draw to the window, if any.
        if self.previewWindowManager is not None:
            if self.shouldMirrorPreview:
                mirroredFrame = numpy.fliplr(self._frame)
                self.previewWindowManager.show(mirroredFrame)
            else:
                self.previewWindowManager.show(self._frame)
  
        # Write to the image file, if any.
        if self.isWritingImage:
            cv2.imwrite(self._imageFilename, self._frame)
            self._imageFilename = None
  
        # Write to the video file, if any.
        self._writeVideoFrame()
  
        # Release the frame.
        self._frame = None
        self._enteredFrame = False
  
    def writeImage(self, filename):
        """Write the next exited frame to an image file."""
        self._imageFilename = filename
  
    def startWritingVideo(self, filename, encoding = cv2.VideoWriter_fourcc('M','J','P','G')):
        """Start writing exited frames to a video file."""
        self._videoFilename = filename
        self._videoEncoding = encoding
  
    def stopWritingVideo(self):
        """Stop writing exited frames to a video file."""
        self._videoFilename = None
        self._videoEncoding = None
        self._videoWriter = None
  
    def _writeVideoFrame(self):
  
        if not self.isWritingVideo:
            return
  
        if self._videoWriter is None:
            fps = self._capture.get(cv2.CAP_PROP_FPS)
            if fps <= 0.0:
                # The capture's FPS is unknown so use an estimate.
                if self._framesElapsed < 20:
                    # Wait until more frames elapse so that the
                    # estimate is more stable.
                    return
                else:
                    fps = self._fpsEstimate
            size = (int(self._capture.get(
                        cv2.CAP_PROP_FRAME_WIDTH)),
                    int(self._capture.get(
                        cv2.CAP_PROP_FRAME_HEIGHT)))
            self._videoWriter = cv2.VideoWriter(
                self._videoFilename, self._videoEncoding,
                fps, size)
  
        self._videoWriter.write(self._frame)
  
class WindowManager(object):
    def __init__(self, windowName, keypressCallback = None):
        self.keypressCallback = keypressCallback
  
        self._windowName = windowName
        self._isWindowCreated = False
  
    @property
    def isWindowCreated(self):
        return self._isWindowCreated
  
    def createWindow(self):
        cv2.namedWindow(self._windowName)
        self._isWindowCreated = True
  
    def show(self, frame):
        cv2.imshow(self._windowName, frame)
  
    def destroyWindow(self):
        cv2.destroyWindow(self._windowName)
        self._isWindowCreated = False
  
    def processEvents(self):
        keycode = cv2.waitKey(1)
        if self.keypressCallback is not None and keycode != -1:
            self.keypressCallback(keycode)
    

cameo.py
import cv2
from managers import WindowManager, CaptureManager
  
class Cameo(object):
    def __init__(self):
        self._windowManager = WindowManager('Cameo', self.onKeypress)
        self._captureManager = CaptureManager(cv2.VideoCapture(0), self._windowManager, True)
  
    def run(self):
        """Run the main loop."""
        self._windowManager.createWindow()
        while self._windowManager.isWindowCreated:
            self._captureManager.enterFrame()
            frame = self._captureManager.frame
  
            if frame is not None:
                # TODO: Filter the frame (Chapter 3).
                pass
  
            self._captureManager.exitFrame()
            self._windowManager.processEvents()
  
    def onKeypress(self, keycode):
        """Handle a keypress.
  
        space  -> Take a screenshot.
        tab    -> Start/stop recording a screencast.
        escape -> Quit.

        """
        if keycode == 32: # space
            self._captureManager.writeImage('screenshot.png')
        elif keycode == 9: # tab
            if not self._captureManager.isWritingVideo:
                self._captureManager.startWritingVideo('screencast.avi')
            else:
                self._captureManager.stopWritingVideo()
        elif keycode == 27: # escape
            self._windowManager.destroyWindow()
    

test3.ipynb
from cameo import Cameo
  
Cameo().run()