Python 如何在opencv中将相机切换为YUY2格式

我试图让我的相机用YUY2格式而不是目前使用的MJPEG格式来拍摄视频。如何在OpenCV中执行此操作

所以我研究了OpenCV中提供的fourcc代码，并尝试了camera.setcv2.CAP_PROP_fourcc，844715353.0。那个号码是YUY2的代码。然而，每当我运行该程序时，它总是返回到NV12格式。我也尝试过使用VideoWriter，但同样的问题还是出现了。它从不切换

    import cv2
    import sys
    import numpy as np
    import time

    fourcc_names = ['CAP_PROP_POS_MSEC', 'CAP_PROP_POS_FRAMES',        'CAP_PROP_POS_AVI_RATIO', 'CAP_PROP_FRAME_WIDTH', 'CAP_PROP_FRAME_HEIGHT', 'CAP_PROP_FPS', 'CAP_PROP_FOURCC', 'CAP_PROP_FRAME_COUNT', 'CAP_PROP_FORMAT', 'CAP_PROP_MODE', 'CAP_PROP_BRIGHTNESS', 'CAP_PROP_CONTRAST', 'CAP_PROP_SATURATION', 'CAP_PROP_HUE', 'CAP_PROP_GAIN', 'CAP_PROP_EXPOSURE', 'CAP_PROP_CONVERT_RGB', 'CAP_PROP_WHITE_BALANCE_BLUE_U', 'CAP_PROP_RECTIFICATION', 'CAP_PROP_MONOCHROME', 'CAP_PROP_SHARPNESS', 'CAP_PROP_AUTO_EXPOSURE', 'CAP_PROP_GAMMA', 'CAP_PROP_TEMPERATURE', 'CAP_PROP_TRIGGER', 'CAP_PROP_TRIGGER_DELAY', 'CAP_PROP_WHITE_BALANCE_RED_V', 'CAP_PROP_ZOOM', 'CAP_PROP_FOCUS', 'CAP_PROP_GUID', 'CAP_PROP_ISO_SPEED', 'CAP_PROP_BACKLIGHT', 'CAP_PROP_PAN', 'CAP_PROP_TILT', 'CAP_PROP_ROLL', 'CAP_PROP_IRIS', 'CAP_PROP_SETTINGS', 'CAP_PROP_BUFFERSIZE', 'CAP_PROP_AUTOFOCUS']
def decode_fourcc(v):
  v = int(v)
  return "".join([chr((v >> 8 * i) & 0xFF) for i in range(4)])

print(cv2.__version__)

camera = cv2.VideoCapture()
camera.set(cv2.CAP_PROP_FOURCC,844715353.0)


#codec = 844715353.0 # YUY2

# print 'fourcc:', decode_fourcc(codec)
fourcc = cv2.VideoWriter_fourcc(*'YUY2')
#camera.set(cv2.CAP_PROP_FOURCC, codec)
camera.open(1)

#print Camera open:', camera.isOpened()
# print camera.get(cv2.CAP_PROP_FOURCC)
# C = camera.get(cv2.CAP_PROP_FOURCC)
# print 'fourcc original:', decode_fourcc(C)
# codec = 0x47504A4D # MJPG
# codec = 844715353.0 # YUY2



camera.set(cv2.CAP_PROP_FRAME_WIDTH, 3264)
camera.set(cv2.CAP_PROP_FRAME_HEIGHT, 2448)
camera.set(cv2.CAP_PROP_FPS, 15.0)

print(camera.get(cv2.CAP_PROP_FRAME_WIDTH))
print (camera.get(cv2.CAP_PROP_FRAME_HEIGHT))
print (camera.get(cv2.CAP_PROP_FPS))
C = camera.get(cv2.CAP_PROP_FOURCC)
print('fourcc:', decode_fourcc(C))

print
for i in range(38):
    print(i, fourcc_names[i], camera.get(i))

while(1):

    camera.grab()
    retval, im = camera.retrieve(0)
    cv2.imshow("image", im)
    k = cv2.waitKey(1) & 0xff
    if k == 27:
        break

camera.release()
cv2.destroyAllWindows()

这是代码的输出。正如你所看到的，fourcc保持NV12，在我设置它时不会切换。我怎样才能让它听呢

4.1.0
3264.0
2448.0
15.0
fourcc: NV12
0 CAP_PROP_POS_MSEC 0.0
1 CAP_PROP_POS_FRAMES 0.0
2 CAP_PROP_POS_AVI_RATIO -1.0
3 CAP_PROP_FRAME_WIDTH 3264.0
4 CAP_PROP_FRAME_HEIGHT 2448.0
5 CAP_PROP_FPS 15.0
6 CAP_PROP_FOURCC 842094158.0
7 CAP_PROP_FRAME_COUNT -1.0
8 CAP_PROP_FORMAT -1.0
9 CAP_PROP_MODE 0.0
10 CAP_PROP_BRIGHTNESS 0.0
11 CAP_PROP_CONTRAST 32.0
12 CAP_PROP_SATURATION 105.0
13 CAP_PROP_HUE 0.0
14 CAP_PROP_GAIN 0.0
15 CAP_PROP_EXPOSURE -7.0
16 CAP_PROP_CONVERT_RGB 1.0
17 CAP_PROP_WHITE_BALANCE_BLUE_U -1.0
18 CAP_PROP_RECTIFICATION -1.0
19 CAP_PROP_MONOCHROME -1.0
20 CAP_PROP_SHARPNESS 3.0
21 CAP_PROP_AUTO_EXPOSURE 1.0
22 CAP_PROP_GAMMA 100.0
23 CAP_PROP_TEMPERATURE 4600.0
24 CAP_PROP_TRIGGER -1.0
25 CAP_PROP_TRIGGER_DELAY -1.0
26 CAP_PROP_WHITE_BALANCE_RED_V -1.0
27 CAP_PROP_ZOOM -1.0
28 CAP_PROP_FOCUS -1.0
29 CAP_PROP_GUID -1.0
30 CAP_PROP_ISO_SPEED -1.0
31 CAP_PROP_BACKLIGHT -1.0
32 CAP_PROP_PAN 1.0
33 CAP_PROP_TILT -1.0
34 CAP_PROP_ROLL -1.0
35 CAP_PROP_IRIS -1.0
36 CAP_PROP_SETTINGS -1.0
37 CAP_PROP_BUFFERSIZE -1.0

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你好，你明白了吗？我也有同样的问题。。。。