In the QVideoWidget container on PyQt, you need to start a video from the computer, on which objects are to be searched through TensorFlow (openCV, cv2). The problem is that when the button is pressed, the video only shows one frame and nothing else. What could be the problem? Made in PyCharm, Python 3.7.
from PyQt5 import QtCore, QtGui, QtWidgets, uiс
import os
import cv2
import numpy as np
import sys
from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtWidgets import QLabel, QVBoxLayout
from PyQt5.QtCore import QThread, pyqtSignal, Qt
from PyQt5.QtGui import QImage, QPixmap
class ThreadOpenCV(QThread):
changePixmap = pyqtSignal(QImage)
def __init__(self, source):
super().__init__()
def run(self):
# MODEL_NAME = 'inference_graph'
VIDEO_NAME = '20201024161726.mp4'
#
# # Grab path to current working directory
CWD_PATH = os.getcwd()
PATH_TO_VIDEO = os.path.join(CWD_PATH, VIDEO_NAME)
cap = cv2.VideoCapture(PATH_TO_VIDEO)
while True:
ret, frame = cap.read()
if ret:
frame_rgb = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
frame_expanded = np.expand_dims(frame_rgb, axis=0)
rgbImage = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
h, w, ch = rgbImage.shape
bytesPerLine = ch * w
convertToQtFormat = QImage(rgbImage.data, w, h, bytesPerLine, QImage.Format_RGB888)
p = convertToQtFormat.scaled(640, 480, Qt.KeepAspectRatio)
self.changePixmap.emit(p)
if cv2.waitKey(1) == ord('q'):
break
cap.release()
cv2.destroyAllWindows()
class Widget(QtWidgets.QMainWindow):
def __init__(self):
super().__init__()
uic.loadUi('fire_detection.ui', self)
self.show()
self.label_video = QLabel()
layout = QVBoxLayout()
layout.addWidget(self.label_video)
self.widget.setLayout(layout)
self.thread = ThreadOpenCV('20201024161726.mp4')
self.thread.changePixmap.connect(self.setImage)
self.btn1.clicked.connect(self.playVideo)
def playVideo(self):
self.thread.start()
def setImage(self, image):
self.label_video.setPixmap(QPixmap.fromImage(image))
if __name__ == '__main__':
app = QtWidgets.QApplication(sys.argv)
mw = Widget()
mw.show()
sys.exit(app.exec_())
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Answer
All problem is because you have wrong indentations – and you run cap.release() inside while-loop so it releases stream after the first frame.
while True:
ret, frame = cap.read()
if ret:
frame_rgb = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
frame_expanded = np.expand_dims(frame_rgb, axis=0)
rgbImage = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
h, w, ch = rgbImage.shape
bytesPerLine = ch * w
convertToQtFormat = QImage(rgbImage.data, w, h, bytesPerLine, QImage.Format_RGB888)
p = convertToQtFormat.scaled(640, 480, Qt.KeepAspectRatio)
self.changePixmap.emit(p)
# --- after `while` ---
cap.release()
You don’t create window in cv2 so you don’t cv2.destroyAllWindows().
And cv2.waitKey(1) will be also useless because the system sends key/mouse events to cv2 only when it displays the window and this window is active (focused).
EDIT:
Full working code. It uses a webcam.
It doesn’t need a UI file.
It has buttons to start and stop streaming,
It has also buttons to switch: RGB <-> GRAYSCALE, NORMAL <-> BLURED.
import os
import sys
import numpy as np
import cv2
from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtCore import Qt, QThread, pyqtSignal
from PyQt5.QtWidgets import QLabel, QVBoxLayout, QPushButton, QWidget
from PyQt5.QtGui import QImage, QPixmap
class ThreadOpenCV(QThread):
changePixmap = pyqtSignal(QImage)
def __init__(self, source):
super().__init__()
self.source = source
self.running = True
self.grayscale = False
self.blur = False
def run(self):
print('start')
cap = cv2.VideoCapture(self.source)
self.running = True
while self.running:
ret, frame = cap.read()
if ret:
if self.grayscale:
frame = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
frame = cv2.cvtColor(frame, cv2.COLOR_GRAY2RGB)
else:
frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
if self.blur:
frame = cv2.blur(frame, (15, 15))
h, w, ch = frame.shape
bytes_per_line = ch * w # PEP8: `lower_case_names` for variables
image = QImage(frame.data, w, h, bytes_per_line, QImage.Format_RGB888)
image = image.scaled(640, 480, Qt.KeepAspectRatio)
self.changePixmap.emit(image)
cap.release()
print('stop')
def stop(self):
self.running = False
class Widget(QtWidgets.QMainWindow):
def __init__(self):
super().__init__()
# MODEL_NAME = 'inference_graph'
VIDEO_NAME = '20201024161726.mp4'
CWD_PATH = os.getcwd()
PATH_TO_VIDEO = os.path.join(CWD_PATH, VIDEO_NAME)
# webcam
PATH_TO_VIDEO = 0
self.thread = ThreadOpenCV(PATH_TO_VIDEO)
self.thread.changePixmap.connect(self.setImage)
layout = QVBoxLayout()
self.label_video = QLabel()
layout.addWidget(self.label_video)
self.btn1 = QPushButton("PLAY")
self.btn1.clicked.connect(self.playVideo)
layout.addWidget(self.btn1)
self.btn_stop = QPushButton("STOP")
self.btn_stop.clicked.connect(self.stopVideo)
layout.addWidget(self.btn_stop)
self.btn_gray = QPushButton("RGB <-> GRAYSCALE")
self.btn_gray.clicked.connect(self.grayVideo)
layout.addWidget(self.btn_gray)
self.btn_blur = QPushButton("NORMAL <-> BLURED")
self.btn_blur.clicked.connect(self.blurVideo)
layout.addWidget(self.btn_blur)
self.widget = QWidget()
self.widget.setLayout(layout)
self.setCentralWidget(self.widget)
def playVideo(self):
self.thread.start()
def stopVideo(self):
self.thread.running = False
def grayVideo(self):
self.thread.grayscale = not self.thread.grayscale
def blurVideo(self):
self.thread.blur = not self.thread.blur
def setImage(self, image):
self.label_video.setPixmap(QPixmap.fromImage(image))
if __name__ == '__main__':
app = QtWidgets.QApplication([])
mw = Widget()
mw.show()
app.exec()
RGB, NORMAL:
GRAYSCALE, BLURED:
