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@allanlei allanlei/motion.py
Created Jun 11, 2014

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Python motion detection. Copied from http://www.raspberrypi.org/forums/viewtopic.php?t=45235
import StringIO
import subprocess
import os
import time
from datetime import datetime
from PIL import Image
# Motion detection settings:
# Threshold (how much a pixel has to change by to be marked as "changed")
# Sensitivity (how many changed pixels before capturing an image)
# ForceCapture (whether to force an image to be captured every forceCaptureTime seconds)
threshold = 10
sensitivity = 20
forceCapture = True
forceCaptureTime = 60 * 60 # Once an hour
# File settings
saveWidth = 1280
saveHeight = 960
diskSpaceToReserve = 40 * 1024 * 1024 # Keep 40 mb free on disk
# Capture a small test image (for motion detection)
def captureTestImage():
command = "raspistill -w %s -h %s -t 0 -e bmp -o -" % (100, 75)
imageData = StringIO.StringIO()
imageData.write(subprocess.check_output(command, shell=True))
imageData.seek(0)
im = Image.open(imageData)
buffer = im.load()
imageData.close()
return im, buffer
# Save a full size image to disk
def saveImage(width, height, diskSpaceToReserve):
keepDiskSpaceFree(diskSpaceToReserve)
time = datetime.now()
filename = "capture-%04d%02d%02d-%02d%02d%02d.jpg" % (time.year, time.month, time.day, time.hour, time.minute, time.second)
subprocess.call("raspistill -w 1296 -h 972 -t 0 -e jpg -q 15 -o %s" % filename, shell=True)
print "Captured %s" % filename
# Keep free space above given level
def keepDiskSpaceFree(bytesToReserve):
if (getFreeSpace() < bytesToReserve):
for filename in sorted(os.listdir(".")):
if filename.startswith("capture") and filename.endswith(".jpg"):
os.remove(filename)
print "Deleted %s to avoid filling disk" % filename
if (getFreeSpace() > bytesToReserve):
return
# Get available disk space
def getFreeSpace():
st = os.statvfs(".")
du = st.f_bavail * st.f_frsize
return du
# Get first image
image1, buffer1 = captureTestImage()
# Reset last capture time
lastCapture = time.time()
while (True):
# Get comparison image
image2, buffer2 = captureTestImage()
# Count changed pixels
changedPixels = 0
for x in xrange(0, 100):
for y in xrange(0, 75):
# Just check green channel as it's the highest quality channel
pixdiff = abs(buffer1[x,y][1] - buffer2[x,y][1])
if pixdiff > threshold:
changedPixels += 1
# Check force capture
if forceCapture:
if time.time() - lastCapture > forceCaptureTime:
changedPixels = sensitivity + 1
# Save an image if pixels changed
if changedPixels > sensitivity:
lastCapture = time.time()
saveImage(saveWidth, saveHeight, diskSpaceToReserve)
# Swap comparison buffers
image1 = image2
buffer1 = buffer2
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