我必须拼接从多 (9) 个相机拍摄的图像。最初，我尝试以 15 FPS 的速率从 2 个摄像机捕获帧。然后，我连接了 4 个摄像头(我还使用了外部供电的 USB 集线器来提供足够的电力)，但我只能看到一个流。
为了测试，我使用了以下脚本:
import numpy as np
import cv2
import imutils
index = 0
arr = []
while True:
cap = cv2.VideoCapture(index)
if not cap.read()[0]:
break
else:
arr.append(index)
cap.release()
index += 1
video_captures = [cv2.VideoCapture(idx) for idx in arr]
while True:
# Capture frame-by-frame
frames = []
frames_preview = []
for i in arr:
# skip webcam capture
if i == 1: continue
ret, frame = video_captures[i].read()
if ret:
frames.append(frame)
small = cv2.resize(frame, (0, 0), fx=0.25, fy=0.25)
frames_preview.append(small)
for i, frame in enumerate(frames_preview):
cv2.imshow('Cam {}'.format(i), frame)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
# When everything is done, release the capture
for video_capture in video_captures:
video_capture.release()
cv2.destroyAllWindows()
摄像头数量有限制吗？有谁知道从多个摄像头捕获帧的正确方法是什么？
最佳答案
要使用 OpenCV 捕获多个流，我建议使用线程，它可以通过将繁重的 I/O 操作减轻到单独的线程来提高性能。由于使用 cv2.VideoCapture().read() 访问网络摄像头/IP/RTSP 流是一个阻塞操作，因此我们的主程序会卡住，直到从摄像头设备读取帧。如果您有多个流，这种延迟肯定是可见的。为了解决这个问题，我们可以使用线程来生成另一个线程来处理使用双端队列并行检索帧，而不是依赖单个线程按顺序获取帧。线程允许在不影响主程序性能的情况下连续读取帧。使用线程和 OpenCV 捕获单个流的想法来自 Python OpenCV multithreading streaming from camera 中的先前答案。 .
但如果你想捕获多个流，仅靠 OpenCV 是不够的。您可以将 OpenCV 与 GUI 框架结合使用，将每张图像拼接到漂亮的显示器上。我会用PyQt4作为框架，qdarkstyle对于 GUI CSS，和 imutils用于 OpenCV 便利功能。
这是我目前使用的相机 GUI 的精简版，没有占位符图像、凭据管理登录页面和相机切换功能。我保留了自动相机重新连接功能，以防互联网中断或相机连接丢失。如上图所示，我只有 8 个摄像头，但添加另一个摄像头非常简单，应该不会影响性能。此相机 GUI 当前的执行速度约为 ~60 FPS，因此它是实时的。您可以使用 PyQt 布局轻松地重新排列布局，因此请随意修改代码!记得更改流链接!
from PyQt4 import QtCore, QtGui
import qdarkstyle
from threading import Thread
from collections import deque
from datetime import datetime
import time
import sys
import cv2
import imutils
class CameraWidget(QtGui.QWidget):
"""Independent camera feed
Uses threading to grab IP camera frames in the background
@param width - Width of the video frame
@param height - Height of the video frame
@param stream_link - IP/RTSP/Webcam link
@param aspect_ratio - Whether to maintain frame aspect ratio or force into fraame
"""
def __init__(self, width, height, stream_link=0, aspect_ratio=False, parent=None, deque_size=1):
super(CameraWidget, self).__init__(parent)
# Initialize deque used to store frames read from the stream
self.deque = deque(maxlen=deque_size)
# Slight offset is needed since PyQt layouts have a built in padding
# So add offset to counter the padding
self.offset = 16
self.screen_width = width - self.offset
self.screen_height = height - self.offset
self.maintain_aspect_ratio = aspect_ratio
self.camera_stream_link = stream_link
# Flag to check if camera is valid/working
self.online = False
self.capture = None
self.video_frame = QtGui.QLabel()
self.load_network_stream()
# Start background frame grabbing
self.get_frame_thread = Thread(target=self.get_frame, args=())
self.get_frame_thread.daemon = True
self.get_frame_thread.start()
# Periodically set video frame to display
self.timer = QtCore.QTimer()
self.timer.timeout.connect(self.set_frame)
self.timer.start(.5)
print('Started camera: {}'.format(self.camera_stream_link))
def load_network_stream(self):
"""Verifies stream link and open new stream if valid"""
def load_network_stream_thread():
if self.verify_network_stream(self.camera_stream_link):
self.capture = cv2.VideoCapture(self.camera_stream_link)
self.online = True
self.load_stream_thread = Thread(target=load_network_stream_thread, args=())
self.load_stream_thread.daemon = True
self.load_stream_thread.start()
def verify_network_stream(self, link):
"""Attempts to receive a frame from given link"""
cap = cv2.VideoCapture(link)
if not cap.isOpened():
return False
cap.release()
return True
def get_frame(self):
"""Reads frame, resizes, and converts image to pixmap"""
while True:
try:
if self.capture.isOpened() and self.online:
# Read next frame from stream and insert into deque
status, frame = self.capture.read()
if status:
self.deque.append(frame)
else:
self.capture.release()
self.online = False
else:
# Attempt to reconnect
print('attempting to reconnect', self.camera_stream_link)
self.load_network_stream()
self.spin(2)
self.spin(.001)
except AttributeError:
pass
def spin(self, seconds):
"""Pause for set amount of seconds, replaces time.sleep so program doesnt stall"""
time_end = time.time() + seconds
while time.time() < time_end:
QtGui.QApplication.processEvents()
def set_frame(self):
"""Sets pixmap image to video frame"""
if not self.online:
self.spin(1)
return
if self.deque and self.online:
# Grab latest frame
frame = self.deque[-1]
# Keep frame aspect ratio
if self.maintain_aspect_ratio:
self.frame = imutils.resize(frame, width=self.screen_width)
# Force resize
else:
self.frame = cv2.resize(frame, (self.screen_width, self.screen_height))
# Add timestamp to cameras
cv2.rectangle(self.frame, (self.screen_width-190,0), (self.screen_width,50), color=(0,0,0), thickness=-1)
cv2.putText(self.frame, datetime.now().strftime('%H:%M:%S'), (self.screen_width-185,37), cv2.FONT_HERSHEY_SIMPLEX, 1.2, (255,255,255), lineType=cv2.LINE_AA)
# Convert to pixmap and set to video frame
self.img = QtGui.QImage(self.frame, self.frame.shape[1], self.frame.shape[0], QtGui.QImage.Format_RGB888).rgbSwapped()
self.pix = QtGui.QPixmap.fromImage(self.img)
self.video_frame.setPixmap(self.pix)
def get_video_frame(self):
return self.video_frame
def exit_application():
"""Exit program event handler"""
sys.exit(1)
if __name__ == '__main__':
# Create main application window
app = QtGui.QApplication([])
app.setStyleSheet(qdarkstyle.load_stylesheet_pyqt())
app.setStyle(QtGui.QStyleFactory.create("Cleanlooks"))
mw = QtGui.QMainWindow()
mw.setWindowTitle('Camera GUI')
mw.setWindowFlags(QtCore.Qt.FramelessWindowHint)
cw = QtGui.QWidget()
ml = QtGui.QGridLayout()
cw.setLayout(ml)
mw.setCentralWidget(cw)
mw.showMaximized()
# Dynamically determine screen width/height
screen_width = QtGui.QApplication.desktop().screenGeometry().width()
screen_height = QtGui.QApplication.desktop().screenGeometry().height()
# Create Camera Widgets
username = 'Your camera username!'
password = 'Your camera password!'
# Stream links
camera0 = 'rtsp://{}:{}@192.168.1.43:554/cam/realmonitor?channel=1&subtype=0'.format(username, password)
camera1 = 'rtsp://{}:{}@192.168.1.45/axis-media/media.amp'.format(username, password)
camera2 = 'rtsp://{}:{}@192.168.1.47:554/cam/realmonitor?channel=1&subtype=0'.format(username, password)
camera3 = 'rtsp://{}:{}@192.168.1.40:554/cam/realmonitor?channel=1&subtype=0'.format(username, password)
camera4 = 'rtsp://{}:{}@192.168.1.44:554/cam/realmonitor?channel=1&subtype=0'.format(username, password)
camera5 = 'rtsp://{}:{}@192.168.1.42:554/cam/realmonitor?channel=1&subtype=0'.format(username, password)
camera6 = 'rtsp://{}:{}@192.168.1.46:554/cam/realmonitor?channel=1&subtype=0'.format(username, password)
camera7 = 'rtsp://{}:{}@192.168.1.41:554/cam/realmonitor?channel=1&subtype=0'.format(username, password)
# Create camera widgets
print('Creating Camera Widgets...')
zero = CameraWidget(screen_width//3, screen_height//3, camera0)
one = CameraWidget(screen_width//3, screen_height//3, camera1)
two = CameraWidget(screen_width//3, screen_height//3, camera2)
three = CameraWidget(screen_width//3, screen_height//3, camera3)
four = CameraWidget(screen_width//3, screen_height//3, camera4)
five = CameraWidget(screen_width//3, screen_height//3, camera5)
six = CameraWidget(screen_width//3, screen_height//3, camera6)
seven = CameraWidget(screen_width//3, screen_height//3, camera7)
# Add widgets to layout
print('Adding widgets to layout...')
ml.addWidget(zero.get_video_frame(),0,0,1,1)
ml.addWidget(one.get_video_frame(),0,1,1,1)
ml.addWidget(two.get_video_frame(),0,2,1,1)
ml.addWidget(three.get_video_frame(),1,0,1,1)
ml.addWidget(four.get_video_frame(),1,1,1,1)
ml.addWidget(five.get_video_frame(),1,2,1,1)
ml.addWidget(six.get_video_frame(),2,0,1,1)
ml.addWidget(seven.get_video_frame(),2,1,1,1)
print('Verifying camera credentials...')
mw.show()
QtGui.QShortcut(QtGui.QKeySequence('Ctrl+Q'), mw, exit_application)
if(sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
QtGui.QApplication.instance().exec_()
相关相机/IP/RTSP、FPS、视频、线程和多处理帖子
关于python - 如何使用 OpenCV 捕获多个摄像头流？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/60155223/