列出可用的相机 OpenCV/Python

Question

我有多个网络摄像头连接到我的 PC，我想 select 一个基于其信息（名称、分辨率等）的摄像头。有没有办法列出 PC 上所有可用的相机，而不是尝试 cv2.VideoCapture()?

中的所有索引

Answer 1

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 the code:

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 return 可用设备的数量，但 OpenCV 没有方法 return 向用户提供。

Windows的相关代码是here:

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

同样，没有 returning m_devices.Get()->Size 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 return 可用设备数量的函数。或者甚至更好地使用您的补丁向 OpenCV 提交拉取请求。

Answer 2

要回答您的问题标题，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

在您的代码上实现该解决方案非常简单。

版本 2

正如@ketza 所注意到的，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 3

第一个安装包： pip 安装 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)

列出可用的相机 OpenCV/Python

List available cameras OpenCV/Python

python

opencv

python-3.7

opencv4

版本 2