is there a way to record videos in kivy?

Question

I am displaying the camera video in Kivy, but I can't find a way to record the video, I tried to use OpenCV Videowriter but because of the updating ( Clock.schedule_interval(self.update, 1.0/33.0)) it is constantly overwriting so the video that it saved is one image, does anybody have an alternative way.

Answer 1

Please look into the below code which may serve your purpose. The main code is taken from the link: https://www.codingforentrepreneurs.com/blog/how-to-record-video-in-opencv-python. I have only adapted for kivy framework (as the question is for kivy solution) and adjusted the frame_per_second to make it consistent with viewing & writing speed.

from kivy.app import App
from kivy.uix.widget import Widget
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.image import Image
from kivy.clock import Clock
from kivy.graphics.texture import Texture
from kivy.properties import StringProperty, NumericProperty

import cv2
import os

# Standard Video Dimensions Sizes
STD_DIMENSIONS =  {
    "480p": (640, 480),
    "720p": (1280, 720),
    "1080p": (1920, 1080),
    "4k": (3840, 2160),
}

# Video Encoding, might require additional installs
# Types of Codes: http://www.fourcc.org/codecs.php
VIDEO_TYPE = {
    'avi': cv2.VideoWriter_fourcc(*'XVID'),
    #'mp4': cv2.VideoWriter_fourcc(*'H264'),
    'mp4': cv2.VideoWriter_fourcc(*'XVID'),
}

class KivyCamera(BoxLayout):
    filename = StringProperty('video.avi')
    frames_per_second = NumericProperty(30.0)
    video_resolution = StringProperty('720p')

    def __init__(self, **kwargs):
        super(KivyCamera, self).__init__(**kwargs)
        self.img1=Image()
        self.add_widget(self.img1)
        self.capture = cv2.VideoCapture(0)
        self.out = cv2.VideoWriter(self.filename, self.get_video_type(self.filename), self.frames_per_second, self.get_dims(self.capture, self.video_resolution))
        Clock.schedule_interval(self.update, 1 / self.frames_per_second)

    def update(self, *args):
        ret, frame = self.capture.read()
        self.out.write(frame)
        buf = cv2.flip(frame, 0).tostring()
        texture = Texture.create(size=(frame.shape[1], frame.shape[0]), colorfmt="bgr")
        texture.blit_buffer(buf, colorfmt="bgr", bufferfmt="ubyte")
        self.img1.texture = texture

    # Set resolution for the video capture
    # Function adapted from https://kirr.co/0l6qmh
    def change_resolution(self, cap, width, height):
        self.capture.set(3, width)
        self.capture.set(4, height)

    # grab resolution dimensions and set video capture to it.
    def get_dims(self, cap, video_resolution='1080p'):
        width, height = STD_DIMENSIONS["480p"]
        if self.video_resolution in STD_DIMENSIONS:
            width, height = STD_DIMENSIONS[self.video_resolution]
        ## change the current caputre device
        ## to the resulting resolution
        self.change_resolution(cap, width, height)
        return width, height

    def get_video_type(self, filename):
        filename, ext = os.path.splitext(filename)
        if ext in VIDEO_TYPE:
          return  VIDEO_TYPE[ext]
        return VIDEO_TYPE['avi']

class CamApp(App):
    def build(self):
        return KivyCamera()

if __name__ == '__main__':
    CamApp().run()