Raspberry Pi with multiple USB webcams at high resolution

gistfile1.txt

The secret is mode must be MJPG instead of default YUYV

```python
import cv2 

cap0 = cv2.VideoCapture('/dev/video0')
cap0.set(cv2.CAP_PROP_FOURCC, cv2.VideoWriter_fourcc(*'MJPG'))
cap0.set(cv2.CAP_PROP_FRAME_WIDTH, 1920)
cap0.set(cv2.CAP_PROP_FRAME_HEIGHT, 1080)

cap2 = cv2.VideoCapture('/dev/video2')
cap2.set(cv2.CAP_PROP_FOURCC, cv2.VideoWriter_fourcc(*'MJPG'))
cap2.set(cv2.CAP_PROP_FRAME_WIDTH, 1920)
cap2.set(cv2.CAP_PROP_FRAME_HEIGHT, 1080)

while True:
  ok, frame = cap0.read()
  if not ok:
    break
  cv2.imshow('cap0', frame)
  
  ok, frame = cap2.read()
  if not ok:
    break
  cv2.imshow('cap2', frame)

  key = cv2.waitKey(1)
  if key == 27:
    break

cap0.release()
cap2.release()
cv2.destroyAllWindows()
```