All we need is an easy explanation of the problem, so here it is.
Try to link PyQt and Opencv video feed, can’t understand how to apply while loop for continuously streaming video. It just take a still picture.Please can anyone help to solve the problem.
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PtQt=5
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Python=3.6.1
class App(QWidget):
def __init__(self):
super().__init__()
self.title = 'PyQt5 Video'
self.left = 100
self.top = 100
self.width = 640
self.height = 480
self.initUI()
def initUI(self):
self.setWindowTitle(self.title)
self.setGeometry(self.left, self.top, self.width, self.height)
self.resize(1800, 1200)
#create a label
label = QLabel(self)
cap = cv2.VideoCapture(0)
ret, frame = cap.read()
rgbImage = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
convertToQtFormat = QtGui.QImage(rgbImage.data, rgbImage.shape[1], rgbImage.shape[0],
QtGui.QImage.Format_RGB888)
convertToQtFormat = QtGui.QPixmap.fromImage(convertToQtFormat)
pixmap = QPixmap(convertToQtFormat)
resizeImage = pixmap.scaled(640, 480, QtCore.Qt.KeepAspectRatio)
QApplication.processEvents()
label.setPixmap(resizeImage)
self.show()
if __name__ == '__main__':
app = QApplication(sys.argv)
ex = App()
sys.exit(app.exec_())
How to solve :
I know you bored from this bug, So we are here to help you! Take a deep breath and look at the explanation of your problem. We have many solutions to this problem, But we recommend you to use the first method because it is tested & true method that will 100% work for you.
Method 1
The problem is that the function that obtains the image is executed only once and not updating the label.
The correct way is to place it inside a loop, but it will result in blocking the main window. This blocking of main window can be solved by using the QThread class and send through a signal QImage to update the label. For example:
import cv2
import sys
from PyQt5.QtWidgets import QWidget, QLabel, QApplication
from PyQt5.QtCore import QThread, Qt, pyqtSignal, pyqtSlot
from PyQt5.QtGui import QImage, QPixmap
class Thread(QThread):
changePixmap = pyqtSignal(QImage)
def run(self):
cap = cv2.VideoCapture(0)
while True:
ret, frame = cap.read()
if ret:
# https://stackoverflow.com/a/55468544/6622587
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)
class App(QWidget):
def __init__(self):
super().__init__()
[...]
self.initUI()
@pyqtSlot(QImage)
def setImage(self, image):
self.label.setPixmap(QPixmap.fromImage(image))
def initUI(self):
self.setWindowTitle(self.title)
self.setGeometry(self.left, self.top, self.width, self.height)
self.resize(1800, 1200)
# create a label
self.label = QLabel(self)
self.label.move(280, 120)
self.label.resize(640, 480)
th = Thread(self)
th.changePixmap.connect(self.setImage)
th.start()
self.show()
Method 2
Updating this for PySide2 and qimage2ndarray
from PySide2.QtCore import *
from PySide2.QtGui import *
import cv2 # OpenCV
import qimage2ndarray # for a memory leak,see gist
import sys # for exiting
# Minimal implementation...
def displayFrame():
ret, frame = cap.read()
frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
image = qimage2ndarray.array2qimage(frame)
label.setPixmap(QPixmap.fromImage(image))
app = QApplication([])
window = QWidget()
# OPENCV
cap = cv2.VideoCapture(0)
cap.set(cv2.CAP_PROP_FRAME_WIDTH, 320)
cap.set(cv2.CAP_PROP_FRAME_HEIGHT, 240)
# timer for getting frames
timer = QTimer()
timer.timeout.connect(displayFrame)
timer.start(60)
label = QLabel('No Camera Feed')
button = QPushButton("Quiter")
button.clicked.connect(sys.exit) # quiter button
layout = QVBoxLayout()
layout.addWidget(button)
layout.addWidget(label)
window.setLayout(layout)
window.show()
app.exec_()
# See also: https://gist.github.com/bsdnoobz/8464000
Method 3
Thank you Taimur Islam for the question.
Thank you eyllanesc for wonderful answering and I have modified your code little bit. I used PtQt=4 Python=2.7 and I didn’t use opencv
import sys
import numpy as np
import flycapture2 as fc2
from PyQt4.QtCore import (QThread, Qt, pyqtSignal)
from PyQt4.QtGui import (QPixmap, QImage, QApplication, QWidget, QLabel)
class Thread(QThread):
changePixmap = pyqtSignal(QImage)
def __init__(self, parent=None):
QThread.__init__(self, parent=parent)
self.cameraSettings()
def run(self):
while True:
im = fc2.Image()
self.c.retrieve_buffer(im)
a = np.array(im)
rawImage = QImage(a.data, a.shape[1], a.shape[0], QImage.Format_Indexed8)
self.changePixmap.emit(rawImage)
def cameraSettings(self):
print(fc2.get_library_version())
self.c = fc2.Context()
numberCam = self.c.get_num_of_cameras()
print(numberCam)
self.c.connect(*self.c.get_camera_from_index(0))
print(self.c.get_camera_info())
m, f = self.c.get_video_mode_and_frame_rate()
print(m, f)
print(self.c.get_property_info(fc2.FRAME_RATE))
p = self.c.get_property(fc2.FRAME_RATE)
print(p)
self.c.set_property(**p)
self.c.start_capture()
class App(QWidget):
def __init__(self):
super(App,self).__init__()
self.title = 'PyQt4 Video'
self.left = 100
self.top = 100
self.width = 640
self.height = 480
self.initUI()
def initUI(self):
self.setWindowTitle(self.title)
self.setGeometry(self.left, self.top, self.width, self.height)
self.resize(800, 600)
# create a label
self.label = QLabel(self)
self.label.move(0, 0)
self.label.resize(640, 480)
th = Thread(self)
th.changePixmap.connect(lambda p: self.setPixMap(p))
th.start()
def setPixMap(self, p):
p = QPixmap.fromImage(p)
p = p.scaled(640, 480, Qt.KeepAspectRatio)
self.label.setPixmap(p)
if __name__ == '__main__':
app = QApplication(sys.argv)
ex = App()
ex.show()
sys.exit(app.exec_())
Note: Use and implement method 1 because this method fully tested our system.
Thank you 🙂
All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0