I have faced the same problem in trying to get high speed recording for games. This was the fastest solution I was able to find for Windows. The code is using raw buffer objects and leads to around ~27 FPS. I cannot find the original post on which this code is based, but if someone finds it I will add the reference.
Note that the framerate will significantly increase if you make the region smaller than 1920x1080.
"""
Alternative screen capture device, when there is no camera of webcam connected
to the desktop.
"""
import logging
import sys
import time
import cv2
import numpy as np
if sys.platform == 'win32':
import win32gui, win32ui, win32con, win32api
else:
logging.warning(f"Screen capture is not supported on platform: `{sys.platform}`")
from collections import namedtuple
class ScreenCapture:
"""
Captures a fixed region of the total screen. If no region is given
it will take the full screen size.
region_ltrb: Tuple[int, int, int, int]
Specific region that has to be taken from the screen using
the top left `x` and `y`, bottom right `x` and `y` (ltrb coordinates).
"""
__region = namedtuple('region', ('x', 'y', 'width', 'height'))
def __init__(self, region_ltrb=None):
self.region = region_ltrb
self.hwin = win32gui.GetDesktopWindow()
# Time management
self._time_start = time.time()
self._time_taken = 0
self._time_average = 0.04
def __getitem__(self, item):
return self.screenshot()
def __next__(self):
return self.screenshot()
def __enter__(self):
return self
def __exit__(self, exc_type, exc_val, exc_tb):
self.close()
if exc_type and isinstance(exc_val, StopIteration):
return True
return False
@staticmethod
def screen_dimensions():
""" Retrieve total screen dimensions. """
left = win32api.GetSystemMetrics(win32con.SM_XVIRTUALSCREEN)
top = win32api.GetSystemMetrics(win32con.SM_YVIRTUALSCREEN)
height = win32api.GetSystemMetrics(win32con.SM_CYVIRTUALSCREEN)
width = win32api.GetSystemMetrics(win32con.SM_CXVIRTUALSCREEN)
return left, top, height, width
@property
def fps(self):
return int(1 / self._time_average) * (self._time_average > 0)
@property
def region(self):
return self._region
@property
def size(self):
return self._region.width, self._region.height
@region.setter
def region(self, value):
if value is None:
self._region = self.__region(*self.screen_dimensions())
else:
assert len(value) == 4, f"Region requires 4 input, x, y of left top, and x, y of right bottom."
left, top, x2, y2 = value
width = x2 - left + 1
height = y2 - top + 1
self._region = self.__region(*list(map(int, (left, top, width, height))))
def screenshot(self, color=None):
"""
Takes a part of the screen, defined by the region.
:param color: cv2.COLOR_....2...
Converts the created BGRA image to the requested image output.
:return: np.ndarray
An image of the region in BGRA values.
"""
left, top, width, height = self._region
hwindc = win32gui.GetWindowDC(self.hwin)
srcdc = win32ui.CreateDCFromHandle(hwindc)
memdc = srcdc.CreateCompatibleDC()
bmp = win32ui.CreateBitmap()
bmp.CreateCompatibleBitmap(srcdc, width, height)
memdc.SelectObject(bmp)
memdc.BitBlt((0, 0), (width, height), srcdc, (left, top), win32con.SRCCOPY)
signed_ints_array = bmp.GetBitmapBits(True)
img = np.frombuffer(signed_ints_array, dtype='uint8')
img.shape = (height, width, 4)
srcdc.DeleteDC()
memdc.DeleteDC()
win32gui.ReleaseDC(self.hwin, hwindc)
win32gui.DeleteObject(bmp.GetHandle())
# This makes sure that the FPS are taken in comparison to screenshots rates and vary only slightly.
self._time_taken, self._time_start = time.time() - self._time_start, time.time()
self._time_average = self._time_average * 0.95 + self._time_taken * 0.05
if color is not None:
return cv2.cvtColor(img, color)
return img
def show(self, screenshot=None):
""" Displays an image to the screen. """
image = screenshot if screenshot is not None else self.screenshot()
cv2.imshow('Screenshot', image)
if cv2.waitKey(1) & 0xff == ord('q'):
raise StopIteration
return image
def close(self):
""" Needs to be called before exiting when `show` is used, otherwise an error will occur. """
cv2.destroyWindow('Screenshot')
def scale(self, src: np.ndarray, size: tuple):
return cv2.resize(src, size, interpolation=cv2.INTER_LINEAR_EXACT)
def save(self, path, screenshot=None):
""" Store the current screenshot in the provided path. Full path, with img name is required.) """
image = screenshot if screenshot is not None else self.screenshot
cv2.imwrite(filename=path, img=image)
if __name__ == '__main__':
# Example usage when displaying.
with ScreenCapture((0, 0, 1920, 1080)) as capture:
for _ in range(100):
capture.show()
print(f"\rCapture framerate: {capture.fps}", end='')
# Example usage as generator.
start_time = time.perf_counter()
for frame, screenshot in enumerate(ScreenCapture((0, 0, 1920, 1080)), start=1):
print(f"\rFPS: {frame / (time.perf_counter() - start_time):3.0f}", end='')
Edit
I noticed some small mistake in the window show
function, and the self.screenshot
calls in the __getitem__
and __next__
method. These have been resolved.
Next to the for example using the ScreenCapture
as a context manager, I added an example of using it as a generator.