无法计算输出视频流上的fps

你可以尝试这样的东西……虽然我不确定你是否想要这个或其他东西……

    
      import datetime
class FPS:
    def init(self):
        …
        …
        self._elapsed = 0
        self._fps = 0
def start(self, ttl):
    self._startTime = datetime.datetime.now()
    self._currentTime = datetime.datetime.now() + datetime.timedelta(seconds=ttl)
    # print('counter started at --> ', self._startTime)
    # print('counter stopped at --> ', self._currentTime)
    return self._startTime, self._currentTime
def elapsed_time(self):
    self._elapsed = (self._currentTime - self._startTime).total_seconds()
    return self._elapsed
def update_frames(self):
    curr, start = self._currentTime, self._startTime
    if curr != start and curr != 0:
        print('updatin frames ...')
        for i in range(int(self._elapsed) + 1):
            self._total_number_of_frames += i
    else:
        self._total_number_of_frames += 1
    self.current_fps()
    print("frames: {}, fps: {}, time spent: {}".format(
        self._total_number_of_frames,
        self._fps,
        self._elapsed
    ))
def current_fps(self):
    self._fps = self._total_number_of_frames / self._elapsed
    return self._fps
if name == ‘main‘:
    fps = FPS()
    ttl = int(input(‘time-to-live in seconds: ‘))
    fps.start(ttl)
    fps.elapsed_time()
    fps.update_frames()
</code>
  

current_fps函数返回一个随时间增加的值，因为self._total_number_of_frames属性将继续增加，而经过的时间将随循环的每次迭代保持或多或少不变。基本上，分子将永远增加，而分母将保持在一个范围内，从而导致值随时间增加。

为了避免这个问题，我们必须允许经过时间函数随着增加的帧一起向上扩展，或者使用一些其他常量来测量我们的fps。让我们选择后者并保持一个单独的计数器变量。

所以你的代码可以像这样重写：

    
      import time  # The time module is easier for our purpose.
class FramesPerSecond:
    def init(self):
        self.startTime = None
        self.total_number_of_frames = 0
        self.counter = 0
        self.frameRate = 1  # The number of seconds to wait for each measurement.
def start(self):
    self.startTime = time.time()  # Returns a UNIX timestamp.
def update_frames(self):
    self.total_number_of_frames += 1
def elapsed_time(self):
    return time.time() - self.startTime
def current_fps(self):
    return self.counter / self.elapsed_time()  # We are measuring against the counter instead of no. of frames.
fps = FramesPerSecond()
fps.start()
while True:  # Your main loop.
# Rest of your code here #
fps.update_frames()
fps.counter += 1  # Count will increase until the if condition executes.
if fps.elapsed_time() > fps.frameRate:  # We measure the fps only after 1 second has passed.
    print("FPS: ", fps.current_fps()) # The frames per second. 
    fps.counter = 0  # reset the counter for next iteration.
    fps.start()  # reset the start time.
</code>