How to overcome VIDIOC_QUERYMENU: Invalid argument error in OpenCV?

Question

linux

There is this code:

import cv,time

cv.NamedWindow("webcam", 1)

cam = cv.CaptureFromCAM(-1)


feed = cv.QueryFrame(cam)
cv.ShowImage("webcam", feed)

time.sleep(2);

I don’t get a picture from the camera
Sees an error:

VIDIOC_QUERYMENU: Invalid argument
VIDIOC_QUERYMENU: Invalid argument
VIDIOC_QUERYMENU: Invalid argument
VIDIOC_QUERYMENU: Invalid argument
VIDIOC_QUERYMENU: Invalid argument
VIDIOC_QUERYMENU: Invalid argument
VIDIOC_QUERYMENU: Invalid argument

Tried to change to cv.CaptureFromCAM(0).
The code:

import cv2
cam = cv2.VideoCapture(-1)

Gives the same error

Answer 1

What version are you using?
Such an example from the Opencv 2.4 tutorial starts up for me with half a kick:

# -*- coding: utf-8 -*-
import numpy as np
import cv2

cap = cv2.VideoCapture(0)

while(True):
    # Capture frame-by-frame
    ret, frame = cap.read()

    # Our operations on the frame come here
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

    # Display the resulting frame
    cv2.imshow('frame',gray)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

# When everything done, release the capture
cap.release()
cv2.destroyAllWindows()