列出可用的相机 OpenCV/Python

Question

我的电脑上连接了多个网络摄像头，我想根据其信息（名称、分辨率等）选择一台摄像头。有没有办法列出 PC 上所有可用的摄像机，而不是尝试 cv2.VideoCapture() 中的所有索引？

Answer 1

要回答问题的标题，您可以使用 while 循环：

import cv2


def list_ports():
    """
    Test the ports and returns a tuple with the available ports 
    and the ones that are working.
    """
    is_working = True
    dev_port = 0
    working_ports = []
    available_ports = []
    while is_working:
        camera = cv2.VideoCapture(dev_port)
        if not camera.isOpened():
            is_working = False
            print("Port %s is not working." %dev_port)
        else:
            is_reading, img = camera.read()
            w = camera.get(3)
            h = camera.get(4)
            if is_reading:
                print("Port %s is working and reads images (%s x %s)" %(dev_port,h,w))
                working_ports.append(dev_port)
            else:
                print("Port %s for camera ( %s x %s) is present but does not reads." %(dev_port,h,w))
                available_ports.append(dev_port)
        dev_port +=1
    return available_ports,working_ports

这是在您的代码上实现的非常简单的解决方案。

版本2

正如 @ketza 注意到的，可能存在工作端口不连续的情况，此版本将在退出 while 循环之前测试至少 5 个非工作端口：

import cv2
    
    
def list_ports():
    """
    Test the ports and returns a tuple with the available ports and the ones that are working.
    """
    non_working_ports = []
    dev_port = 0
    working_ports = []
    available_ports = []
    while len(non_working_ports) < 6: # if there are more than 5 non working ports stop the testing. 
        camera = cv2.VideoCapture(dev_port)
        if not camera.isOpened():
            non_working_ports.append(dev_port)
            print("Port %s is not working." %dev_port)
        else:
            is_reading, img = camera.read()
            w = camera.get(3)
            h = camera.get(4)
            if is_reading:
                print("Port %s is working and reads images (%s x %s)" %(dev_port,h,w))
                working_ports.append(dev_port)
            else:
                print("Port %s for camera ( %s x %s) is present but does not reads." %(dev_port,h,w))
                available_ports.append(dev_port)
        dev_port +=1
    return available_ports,working_ports,non_working_ports

Answer 2

答案是否定的。 OpenCV 没有列出系统上可用视频捕获设备的方法。如果您查看代码，您会发现 OpenCV 当前如何处理不存在的无效设备索引。例如，对于 MacOS，这里是代码：

if ( cameraNum < 0 || devices.count <= NSUInteger(cameraNum) ) {
    fprintf(stderr, "OpenCV: out device of bound (0-%ld): %d\n", devices.count-1, cameraNum);
    [localpool drain];
    return 0;
}

您会看到

devices.count

返回可用设备的数量，但 OpenCV 没有方法将其返回给用户。

Windows 的相关代码是这里：

if ((unsigned)m_deviceID >= m_devices.Get()->Size)
{
    OutputDebugStringA("Video::initGrabber - no video device found\n");
    return false;
}

同样没有将

m_devices.Get()->Size

返回给用户的功能。 Linux 代码有点复杂。

如果您从代码构建 OpenCV，您可以添加一个返回可用设备数量的函数。或者更好地向 OpenCV 提交带有您的补丁的拉取请求。

Answer 3

首先安装包：

pip install pygrabber==0.1 

代码#

from pygrabber.dshow_graph import FilterGraph

graph = FilterGraph()

print(graph.get_input_devices())# list of camera device 

try:
    device =graph.get_input_devices().index("name camera that I want to use it ")

except ValueError as e:

    device = graph.get_input_devices().index("Integrated Webcam")#use default camera if the name of the camera that I want to use is not in my list

vid=cv2.VideoCapture(device)

Answer 4

安装cv2_enumerate_cameras

pip install cv2_enumerate_cameras

枚举相机信息

from cv2_enumerate_cameras import enumerate_cameras

for camera_info in enumerate_cameras():
    print(f'{camera_info.index}: {camera_info.name}')

创建视频捕捉

cap = cv2.VideoCapture(camera_info.index, camera_info.backend)