how to turn off decoding of mjpeg stream from webcam in windows

Question

I am trying read full resolution JPEG frame (4k) from MJPEG camera without decoding in Python/OpenCV. i tried the method from this post Read JPEG frame from MJPEG camera without decoding in Python/OpenCV but video_capture_1.set(cv2.CAP_PROP_CONVERT_RGB, 0) made no different. I still get decoded frames. ("image type of frame1: <class 'numpy.ndarray'>" )

import numpy as np
import cv2
video_capture_1 = cv2.VideoCapture(1, cv2.CAP_DSHOW)
video_capture_1.set(cv2.CAP_PROP_CONVERT_RGB, 0)
video_capture_1.set(cv2.CAP_PROP_BUFFERSIZE, 0)
video_capture_1.set(cv2.CAP_PROP_FOURCC, 
video_capture_1.set(cv2.CAP_PROP_FPS, 10.0)
video_capture_1.set(cv2.CAP_PROP_FRAME_WIDTH, 25920)
video_capture_1.set(cv2.CAP_PROP_FRAME_HEIGHT, 19440)

if not video_capture_1.isOpened():
    print("Cannot open camera1")

fourcc = cv2.VideoWriter_fourcc(*'XVID')
out = cv2.VideoWriter('dualcam.avi', fourcc, 30.0, size)

while True:
    video_capture_1.grab() 
    _, frame1 = video_capture_1.retrieve()  
    #print("frame1:", frame1.shape)
    print('image type of frame1:   ' + str(type(frame1)))

    if (ret1) :
        out.write(frame1)
        cv2.imshow('recording', frame1)
        break
    if cv2.waitKey(1) & 0xFF == ord('e'):
        break
video_capture_1.release()
out.release()
cv2.destroyAllWindows

it did not work. very likely because window don't give you the trun off choice anymore. it started from 2016 https://social.msdn.microsoft.com/Forums/en-US/9d6a8704-764f-46df-a41c-8e9d84f7f0f3/mjpg-encoded-media-type-is-not-available-for-usbuvc-webcameras-after-windows-10-version-1607-os?forum=mediafoundationdevelopment also i coudnot use FFmpeg to connect to my webcam in windows.as windows use only directshow for usb webcam anyway to get around?