CODEWITHSUNDEEP
pythonopencvvideowebcamvideo-processing
user13441281
user13441281

Reputation:

OpenCV is too slow for this

I want to overlay webcam captured video on another video in live. So I have tried the above code,but it's too slow.

Should I shift to another language or lib or something?

Any suggestion or help will be appreciated.

import numpy as np
from cv2 import cv2


def image_resize(image, width = None, height = None, inter = cv2.INTER_AREA):
     # initialize the dimensions of the image to be resized and
     # grab the image size
     dim = None
     (h, w) = image.shape[:2]

     # if both the width and height are None, then return the
     # original image
     if width is None and height is None:
          return image

     # check to see if the width is None
    if width is None:
         # calculate the ratio of the height and construct the
         # dimensions
         r = height / float(h)
         dim = (int(w * r), height)

         # otherwise, the height is None
    else:
         # calculate the ratio of the width and construct the
         # dimensions
         r = width / float(w)
         dim = (width, int(h * r))

    # resize the image
    resized = cv2.resize(image, dim, interpolation = inter)

    # return the resized image
    return resized



cap2 = cv2.VideoCapture('http://192.168.43.1:8080/video')
cap = cv2.VideoCapture('test.mp4')

# Define the codec and create VideoWriter object 
fourcc = cv2.VideoWriter_fourcc(*'XVID')
out = cv2.VideoWriter('sample3.mp4',fourcc,30, (640,480))


# watermark = logo

# cv2.imshow("watermark",watermark)

while(cap.isOpened()):
    ret, frame = cap.read()
    frame = cv2.cvtColor(frame,cv2.COLOR_BGR2BGRA)

    ret2 ,frame2 = cap2.read()
    frame2 = cv2.cvtColor(frame2,cv2.COLOR_BGR2BGRA)

    watermark = image_resize(frame2,height=177)

    if ret==True:
        frame_h, frame_w, frame_c = frame.shape
        overlay = np.zeros((frame_h, frame_w, 4), dtype='uint8')
        overlay[543:543+177,1044:1044+236] = watermark
        cv2.addWeighted(frame, 0.25, overlay, 1.0, 0, frame)
       
        frame = cv2.cvtColor(frame,cv2.COLOR_BGRA2BGR)

        out.write(frame) 

        cv2.imshow('frame',frame)
        if cv2.waitKey(1) & 0xFF == ord('q'):
            break
    else:
        break

# Release everything if job is finished
cap.release()
out.release()
cv2.destroyAllWindows()

Requirement is to overlay webcam live video on another video at bottom smoothly.

Thanks.

Upvotes: 0

Views: 2050

Answers (1)

Petr Blahos
Petr Blahos

Reputation: 2433

Basically, if you want it to be fast, you may not iterate over an image using a python cycle. You are trying to copy the scaled-down image into the empty overlay using 2 nested cycles and that's terribly slow. I do not understand the condition

             if watermark[i,j][3] != 0:

Also this part:

                offset = 0
                h_offset = frame_h - watermark_h -offset
                w_offset = frame_w - watermark_w - offset

should be out of the cycle - they are all constants.

But most importantly instead of cycling over the image you can do:

offset[h_offset:h_offset+watermark_h,w_offset:w_offset+watermark_w] = watermark

After this, I am up from 9 fps to 28 fps.

Upvotes: 3

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