python opencv在使用第三方相机时无法显示视频

Question

I have written below code to read video from camera to display and save .

when I run the below code with option 0 in VideoCapture(0), it works fine and display my webcam video, when I change it to 1 in VideoCapture(1) to get the video from third party camera, I get the error.

I am using the 3rd party camera, with their software it plays the video , I need to capture using my python code ..

with the apbase code qt example also it plays the video

I am not able to play using the below python code

import cv2
import numpy as np
import time
def nothing(x):
    pass

cv2.namedWindow('images')
switch = 'Recording'
cv2.createTrackbar(switch, 'images',0,1,nothing)
cap = cv2.VideoCapture(0)

def writeVideo(frmae):
    pass

switchstatus = 0

currentpos = 0
fourccs = cv2.VideoWriter_fourcc(*'MJPG')
out = cv2.VideoWriter('sample.avi', fourccs, 20.0, (640,480))
created = 0
startrecord = 0



def RecordVideo(frame):
    global out
    global created;
    global startrecord
    print "In the Record video" ,created, startrecord
    if created == 0 and startrecord ==1:
        filename ='test.avi'
        filename=time.strftime("%Y-%m-%d-%H-%M-%S")+'.avi'
        print "filename", filename
        out = cv2.VideoWriter(filename,fourccs, 20.0, (640,480))
        created = 1;
        out.write(frame)
    elif created == 1 and startrecord ==1:
        out.write(frame)


def positionChanged(s):
    global currentpos
    global created
    global startrecord

    print "position changed", s
    currentpos = s
    if s==1:
        startrecord = 1
        created = 0
    else:
        startrecord = 0
    if created==1:
        created =0
        out.release()




def switchchanged(s):
    global switchstatus;
    if switchstatus != s:
        switchstatus = s
        positionChanged(s)



while(1):
    ret, frame = cap.read()
        RecordVideo(frame)
    cv2.imshow('images',frame)

    s = cv2.getTrackbarPos(switch,'images')

    switchchanged(s)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        out.release()
        cv2.destroyAllWindows()
        break

Error

File "C:\\Python32Bit\\video.py, lime 89, in cv2.imshow('images',frame)

eror :........\\opencv\\modules\\hihggui\\src\\window.cpp:error:(-215) size.width>0 && size.height>0 in function cv::imshow

Answer 1

I got this to work by disabling the built-in webcam from the windows hardware settings menu. I did this on a friend's computer so I don't have access to it now, but check this out. I believe windows won't let openCV use any other video capture device but the 0th, so you have to make any camera you want to use the first in the hardware list.

Answer 2

cap = cv2.VideoCapture(0+cv2.CAP_DSHOW)
cap.set(cv2.CAP_PROP_FRAME_WIDTH, 1920)
cap.set(cv2.CAP_PROP_FRAME_HEIGHT, 1080)

it indeed solved my problem.

Answer 3

You just change VideoCapture(0) to VideoCapture (1) If you using external camera. If we using computer camera then we are write (0) So you can make that change