Raspberry Pi USB WebCamera Recording for security timelapse *Without much CPU overhead*

seccam.py

# Copyright (c) 2016 Laxmianarayan G Kamath A [email protected]
# 
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Lesser General Public License for more details.
# 
# You should have received a copy of the GNU Lesser General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

# This program allows you to use the RaspBerry Pi as a security DVR for :
#    USB Webcamera and NOT the RaspberryPi Camera
# The most important feature of this program is that it uses very little CPU Overhead 
# (unlike my previous attempt which used mencoder)
#
# Usage:
#     python seccam.py [filename without extension] [camera number to use] [delay between frames]
# 
# defaults: 
# Filename = current timestamp as YYYYMMDD_hhmmss.mov
# camera number to use = 0
# delay between frame = 2



import cv2 
import time
import sys
import os

argv = sys.argv
delay = int(argv[3]) if len(argv) > 3 else 2
camnum = int(argv[2]) if len(argv) > 2 else 0
vc = cv2.VideoCapture( camnum )
vc.set(cv2.cv.CV_CAP_PROP_FRAME_WIDTH,640)
vc.set(cv2.cv.CV_CAP_PROP_FRAME_HEIGHT,480)
res, i = vc.read()
height,width,depth = i.shape

outfilename = argv[1] if len(argv) > 1 else time.strftime('%Y%m%d_%H%M%S_%Z') 
outfilename += '.mov'
print outfilename


debug = os.environ.keys().count('DEBUG') > 0

vw = cv2.VideoWriter(outfilename, cv2.cv.FOURCC('m','p','4','v'),24,(width,height))

done = False
frctr = 0
while not done:
    try:
        time.sleep(delay)
        res,i = vc.read()
        if res:
	    ctime = time.strftime('%Y/%m/%d %H:%M:%S %Z')
            cv2.putText(i,ctime,(30,30), cv2.FONT_HERSHEY_PLAIN, 1.0, (0,0,0))
            cv2.putText(i,ctime,(31,31), cv2.FONT_HERSHEY_PLAIN, 1.0, (255,255,255))
            vw.write(i)
	frctr += 1
        if debug:
	     sys.stderr.write("frame:%d\r" % (frctr))
    except KeyboardInterrupt:
        done = True
vw.release()