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

I managed to run the code on opencv 4 and ubuntu 18 by changing the line 27 to:
cv2.VideoWriter_fourcc(*'X264')
and the lines 20 to 23 as:
width = cap.get(cv2.CAP_PROP_FRAME_WIDTH) # float
height = cap.get(cv2.CAP_PROP_FRAME_HEIGHT) # float

It gives me this error :

objc[44260]: Class RunLoopModeTracker is implemented in both /Users/ben/anaconda3/lib/python3.7/site-packages/cv2/.dylibs/QtCore (0x11686b7f0) and /Users/ben/anaconda3/lib/libQt5Core.5.9.7.dylib (0x12f501a80). One of the two will be used. Which one is undefined.
QObject::moveToThread: Current thread (0x7ffc85f31e40) is not the object's thread (0x7ffc85d98d30).
Cannot move to target thread (0x7ffc85f31e40)

You might be loading two sets of Qt binaries into the same process. Check that all plugins are compiled against the right Qt binaries. Export DYLD_PRINT_LIBRARIES=1 and check that only one set of binaries are being loaded.
qt.qpa.plugin: Could not load the Qt platform plugin "cocoa" in "" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

Available platform plugins are: cocoa, minimal, offscreen.

It gives me this error :

objc[44260]: Class RunLoopModeTracker is implemented in both /Users/ben/anaconda3/lib/python3.7/site-packages/cv2/.dylibs/QtCore (0x11686b7f0) and /Users/ben/anaconda3/lib/libQt5Core.5.9.7.dylib (0x12f501a80). One of the two will be used. Which one is undefined.
QObject::moveToThread: Current thread (0x7ffc85f31e40) is not the object's thread (0x7ffc85d98d30).
Cannot move to target thread (0x7ffc85f31e40)

You might be loading two sets of Qt binaries into the same process. Check that all plugins are compiled against the right Qt binaries. Export DYLD_PRINT_LIBRARIES=1 and check that only one set of binaries are being loaded.
qt.qpa.plugin: Could not load the Qt platform plugin "cocoa" in "" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

Available platform plugins are: cocoa, minimal, offscreen.

I am having the same exact issue and its driving me crazy. Three hours and the same thing. please help :( anyone out there.

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