cv2 从具有特定时间的图像数组创建视频

Question

I have here the code to generate video from array of images, it is working fine but it only displays each image for less than 1 sec how can i control the displaying time of the images for example pic 1 display in the video for 3 sec and pic 2 for 5 sec and so on >>

import cv2
import numpy as np

img=[]
img.append(cv2.imread('/sent0word0.jpg'))
img.append(cv2.imread('/sent1word3.jpg'))
img.append(cv2.imread('/sent0word1.jpg'))

height, width, layers = img[2].shape
size = (width,height)

out = cv2.VideoWriter('project.avi',cv2.VideoWriter_fourcc(*'DIVX'), 15, size)

for i in range(len(img)):
    image=cv2.resize(img[i],size)
    out.write(image)
out.release()

Answer 1

• To play image for 3 seconds add same image 3 times to frames list (1 list element = 1 second)
• Set fps to 1 in VideoWriter

Code:

import cv2

frames = [cv2.imread('frame1.jpg'),
          cv2.imread('frame2.jpg'),
          cv2.imread('frame2.jpg'),
          cv2.imread('frame2.jpg'),
          cv2.imread('frame2.jpg')]

height, width, _ = frames[0].shape
out = cv2.VideoWriter('output.avi', cv2.VideoWriter_fourcc(*'DIVX'), 1, (width, height))
[out.write(f) for f in frames]
out.release()

Output:

Answer 2

Each image is a frame in your video, since you set the frames per second to 15 in your cv2.VideoWriter object, it will display those images rather quick. What you could do is lower the frames per seconds or duplicate your frames to match up the frames per second.

Answer 3

What you want is to change the fps dynamically. From the documentation of VideoWriter :

cv2.VideoWriter.open(filename, fourcc, fps, frameSize[, isColor]) → retval

You're interested in the third parameter that you've set to 15fps . In particular this means that you're currently displaying 15 images per seconds.

This means that if you want to display 1 image in 1 second you're looking for an fps of 1. If you want 1 image for 3 seconds you want a fps equal to 1/3 and so on. Generally 1 image for n seconds requires an fps of 1/n .

Keeping all of this in consideration there is no direct way to change the number of fps in a dynamic way but there is a workaround. You could set the fps at the highest that you have and then just display the frames with a lower fps multiple times.

The way to build the code depends on your particular situation. Tell me if you need more info.

Edit: I've found something that may help you out on the OpenCV forum .

Answer 4

import cv2
import numpy as np

img=[]
img.append(cv2.imread('C:/Users/STC/Desktop/TextToSp/sent0word0.jpg'))
img.append(cv2.imread('C:/Users/STC/Desktop/TextToSp/sent1word3.jpg'))
img.append(cv2.imread('C:/Users/STC/Desktop/TextToSp/sent0word1.jpg'))

height, width, layers = img[2].shape
size = (width,height)

out = cv2.VideoWriter('project.avi',cv2.VideoWriter_fourcc(*'DIVX'), 1.0, size)
each_image_duration = 5 # in secs

for i in range(len(img)):
    image=cv2.resize(img[i],size)
    for _ in range(each_image_duration):
        out.write(image)
out.release()