How to show 2 usb cameras with openCV and python - python

I try to show 2 usb_cameras with 2 differents windows at the same time using openCV -python (I want to implement stereo vision and deep estimation), but I only obtain one window at a time. Can you help me please!
import threading
import cv2
def usb_video1():
cap = cv2.VideoCapture(2)
cap.set(cv2.CAP_PROP_FRAME_WIDTH, 200)
cap.set(cv2.CAP_PROP_FRAME_HEIGHT, 150)
while(True):
ret, frame = cap.read()
if ret == True:
cv2.imshow('frame',frame)
if cv2.waitKey(1) & 0xFF == ord('s'):
break
else :
break
cap.release()
cv2.destroyAllWindows()
def usb_video2():
cap = cv2.VideoCapture(4)
cap.set(cv2.CAP_PROP_FRAME_WIDTH, 200)
cap.set(cv2.CAP_PROP_FRAME_HEIGHT, 150)
while(True):
ret, frame = cap.read()
if ret == True:
cv2.imshow('frame_2',frame)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
else :
break
cap.release()
cv2.destroyAllWindows()
t01 = threading.Thread(target=usb_video1())
t02 = threading.Thread(target=usb_video2())
t01.start()
t02.start()

Related

Error in OpenCV code: cv2.error: OpenCV(4.5.1)

I am writing a code in python using the OpenCV Python library.
I wanted to access the webcam using the code written, but after executing the code in the terminal, the following error arises again and again.
Code written:
import numpy as np
import cv2
cap = cv2.VideoCapture(0)
while True:
ret, frame = cap.read()
cv2.imshow('frame', frame)
if cv2.waitKey(1) == ord('q'):
break
cap.release()
cv2.destroyAllWindows()
Error:
If this is a camera installed on your computer:
import cv2
cap = cv2.VideoCapture(0)
while True:
ret, frame = cap.read()
cv2.imshow('frame', frame)
if cv2.waitKey(1) == ord('q'):
break
cap.release()
cv2.destroyAllWindows()
If this is a camera connected via USB:
import cv2
cap = cv2.VideoCapture(1)
while True:
ret, frame = cap.read()
cv2.imshow('frame', frame)
if cv2.waitKey(1) == ord('q'):
break
cap.release()
cv2.destroyAllWindows()

I want to increase the resolution of my webcam in OpenCV Python

Is there a way to increase the webcam resolution of my webcam in OpenCV Python. The default value is 640x480 but, I want it to be 1365x730. Here's my code:
import cv2
cap = cv2.VideoCapture(0)
while(1):
_, frame = cap.read()
cv2.imshow('frame', frame)
key = cv2.waitKey(1)
if key == 27:
break
cap.release()
cv2.destroyAllWindows()
import cv2
cap = cv2.VideoCapture(0)
cam.set(cv2.CAP_PROP_FRAME_WIDTH, 1280)
cam.set(cv2.CAP_PROP_FRAME_HEIGHT, 720)
while(1):
_, frame = cap.read()
cv2.imshow('frame', frame)
key = cv2.waitKey(1)
if key == 27:
break
cap.release()
cv2.destroyAllWindows()

can't save video file in opencv

I have videostreams and I'd like to convert them to foreground detected videos on which everything is white that moving and all others are black.
When I run this below script nothing happens, python ide just waits. Should I wait, does the video render or do i make something wrong?
Thanks
import cv2
import numpy
cap = cv2.VideoCapture('2018_02_28_12_07_42.h264')
fgbg = cv2.createBackgroundSubtractorMOG2()
fourcc = cv2.VideoWriter_fourcc(*'XVID')
out = cv2.VideoWriter('output.avi',fourcc, 20.0, (640,480))
#while(cap.isOpened()):
while True:
ret, frame = cap.read()
#if ret == True:
fgmask = fgbg.apply(frame)
out.write(frame)
cv2.imshow('original', frame)
cv2.imshow('fg', fgmask)
k = cv2.waitKey(30) & 0xff
if k == 27:
break
cap.release()
out.release()
cv2.destroyWindows()

How to capture a picture in opencv

python newbie here I have following code which I'm using to capture a picture using opencv. It captures the picture when I press q key on keyboard.
Working fine so far.
import cv2
cap = cv2.VideoCapture(0)
while(True):
ret, frame = cap.read()
rgb = cv2.cvtColor(frame, cv2.COLOR_BGR2BGRA)
cv2.imshow('frame', rgb)
if cv2.waitKey(1) & 0xFF == ord('q'):
out = cv2.imwrite('capture.jpg', frame)
break
cap.release()
cv2.destroyAllWindows()
I need it to capture the picture when I give a command (like 'Capture now'). Can anyone help me how to capture a frame when user gives the written command rather than by pressing the key. Thanks
You can write like
reqCommand = 'Capture_pic'
command = input('Enter command')
if command == reqCommand:
out = cv2.imwrite('capture.jpg', frame)
Update:
This update is to make it enable to not block the execution of the program
import cv2
import threading
command = None
def process():
while True:
command = input('Enter command')
thread = threading.Thread(target=process)
thread.start()
cap = cv2.VideoCapture(0)
reqCommand = 'Capture_pic'
while(True):
ret, frame = cap.read()
rgb = cv2.cvtColor(frame, cv2.COLOR_BGR2BGRA)
cv2.imshow('frame', rgb)
if command == reqCommand:
out = cv2.imwrite('capture.jpg', frame)
thread.terminate()
break
cap.release()
cv2.destroyAllWindows()

OpenCV wont' capture from MacBook Pro iSight

Since a couple of days I can't open my iSight camera from inside an opencv application any more. cap = cv2.VideoCapture(0) returns, and cap.isOpened() returns true. However, cap.grab() just returns false. Any ideas?
Example Code:
import cv2
cv2.namedWindow("preview")
vc = cv2.VideoCapture(0)
rval = True
while rval:
rval, frame = vc.read()
cv2.imshow("preview", frame)
key = cv2.waitKey(20)
if key == 27: # exit on ESC
break
Mac OS 10.8.5
Python 2.7.5 (but also not working from inside a C++ app)
OpenCV 2.4.6.1
This is how I got the camera working for your code (on OSX 10.6):
import cv2
cv2.namedWindow("preview")
vc = cv2.VideoCapture(0)
rval, frame = vc.read()
while True:
if frame is not None:
cv2.imshow("preview", frame)
rval, frame = vc.read()
if cv2.waitKey(1) & 0xFF == ord('q'):
break
I had a segmentation fault after I grab an image. It turned out that I used cv2.destroyAllWindows() before cap.release(). Below I show working code.
cap = cv2.VideoCapture(0)
while(True):
ret, frame = cap.read()
gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
cv2.imshow('frame',gray)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
#do some ops
cap.release()
cv2.imshow("output", output)
cv2.waitKey(0)
cv2.destroyAllWindows()
This code works on El Captain.

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