Stream and save video in Python with OpenCV

save-video-w-opencv.py

# For more info: http://docs.opencv.org/3.0-beta/doc/py_tutorials/py_gui/py_video_display/py_video_display.html
import cv2
import numpy as np
import os

FILE_OUTPUT = 'output.avi'

# Checks and deletes the output file
# You cant have a existing file or it will through an error
if os.path.isfile(FILE_OUTPUT):
    os.remove(FILE_OUTPUT)

# Playing video from file:
# cap = cv2.VideoCapture('vtest.avi')
# Capturing video from webcam:
cap = cv2.VideoCapture(0)

currentFrame = 0

# Get current width of frame
width = cap.get(cv2.cv.CV_CAP_PROP_FRAME_WIDTH)   # float
# Get current height of frame
height = cap.get(cv2.cv.CV_CAP_PROP_FRAME_HEIGHT) # float


# Define the codec and create VideoWriter object
fourcc = cv2.cv.CV_FOURCC(*'X264')
out = cv2.VideoWriter(FILE_OUTPUT,fourcc, 20.0, (int(width),int(height)))

# while(True):
while(cap.isOpened()):
    # Capture frame-by-frame
    ret, frame = cap.read()

    if ret == True:
        # Handles the mirroring of the current frame
        frame = cv2.flip(frame,1)

        # Saves for video
        out.write(frame)

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

    # To stop duplicate images
    currentFrame += 1

# When everything done, release the capture
cap.release()
out.release()
cv2.destroyAllWindows()

# Potential Error:
# OpenCV: Cannot Use FaceTime HD Kamera
# OpenCV: camera failed to properly initialize!
# Segmentation fault: 11
#
# Solution:
# I solved this by restarting my computer.
# http://stackoverflow.com/questions/40719136/opencv-cannot-use-facetime/42678644#42678644

For those using cv2 v4+, I solved using

width = self.video.get(cv2.CAP_PROP_FRAME_WIDTH)  
height = self.video.get(cv2.CAP_PROP_FRAME_HEIGHT)

fourcc = cv2.VideoWriter.fourcc(*'X264')

as explained here