在for循环中更改亮度只接受第一个参数

Question

我正在分析一个非常低帧率的视频。如果视频中的某些内容符合我的要求，则计数将增加1。一旦计数达到3，屏幕亮度将降低，然后再次增加，然后返回到默认设置(开始亮度)。

我一开始就是这样得到当前屏幕亮度的：

objWMI = GetObject('winmgmts:\\\\.\\root\\WMI').InstancesOf('WmiMonitorBrightness')
for obj in objWMI:
    startpointbrightness = obj.CurrentBrightness
print(startpointbrightness)

我的循环定义如下(以降低帧率)：

frame_rate = 0.3
prev = 0
cap = cv2.VideoCapture(0)
framerate = cap.get(5)
count = 0

while True:

# Grab a single frame of video every frame-rate
    time_elapsed = time.time() - prev
    ret, frame = cap.read()
    if time_elapsed > 1./frame_rate:
        prev = time.time()

        if label == "action_happened":
            count = count + 1
            if count == 3:
                methods.WmiSetBrightness(0, 0)
                methods.WmiSetBrightness(1, 100)
                methods.WmiSetBrightness(1, startpointbrightness)

问题是只处理最后一条if语句中的第一行methods.WmiSetBrightness(0，0)

任何帮助都非常感谢。谢谢!

Answer 1

https://docs.microsoft.com/en-us/windows/win32/wmicoreprov/wmisetbrightness-method-in-class-wmimonitorbrightnessmethods

WmiSetBrightness方法接受两个参数。第一个是以秒为单位的时间。你指的是第一个参数中的1秒吗？

Answer 2

我问了鸭子，但找不到任何文档来真正解释超时参数的用途。

我确实找到了这个项目(我不运行Windows，所以我无法检查)，可以成功地使用相同的调用：

https://github.com/blackholeearth/Win10_BrightnessSlider/blob/master/Win10_BrightnessSlider/Form1.cs

foreach (ManagementObject mObj in objectCollection)
{
    mObj.InvokeMethod("WmiSetBrightness",
                      new Object[] { UInt32.MaxValue, targetBrightness });
    break;
}

循环遍历对象并总是中断，基本上就是在列表中的第一个对象上调用方法。我不知道这是不是你想要的。

我建议您不要尝试同时进行所有这三个设置。相反，您应该构建一个状态机，并在每次通过外部循环时更新它：

def set_monitor_brightness(percent):
    """Under Windows, use WMI to set monitor brightness to a percentage of maximum"""
    timeout = 2 ** 32 - 1
    methods.WmiSetBrightness(timeout, percent)

Monitor_blink_state = None

def start_monitor_blink():
    """ Begin a 'monitor blink' to draw the user's attention"""

    global Monitor_blink_state
    Monitor_blink_state = "MIN"
    set_monitor_brightness(0)

def update_monitor_blink():
    """Update a monitor blink, if one is happening."""

    global Monitor_blink_state

    if Monitor_blink_state is None:
        return

    if Monitor_blink_state == "MIN":
        Monitor_blink_state = "MAX"
        set_monitor_brightness(100)
    elif Monitor_blink_state == "MAX":
        Monitor_blink_state = None
        set_monitor_brightness(startpointbrightness)

# ... later ...        

while True:
    update_monitor_blink()

    # rest of your code

        if count == 3:
            start_monitor_blink()