alex190030 alex190030 - 5 days ago 5
Python Question

cv2.VideoWriter() Doesn't work on the Raspberry Pi with the Raspicam

I use the following code to capture motion on the Raspicam, the issue is that cv2.VideoWriter() doesn't seem to work on the Pi, I have read about this issue and I have installed the v4l driver yet it still doesn't appear to work.

If anyone has an alternative method for capturing video or a solution for this one he would be of immense help to me.

from picamera.array import PiRGBArray
from picamera import PiCamera
import time
import cv2
import numpy
from datetime import datetime, timedelta

MOTION_RECORD_TIME = timedelta(seconds = 3)


def have_motion(frame1, frame2):
if frame1 is None or frame2 is None:
return False
delta = cv2.absdiff(frame1, frame2)
thresh = cv2.threshold(delta, 25, 255, cv2.THRESH_BINARY)[1]
return numpy.sum(thresh) > 0

camera = PiCamera()
camera.resolution = (640, 480)
camera.framerate = 32
rawCapture = PiRGBArray(camera, size=(640, 480))
time.sleep(0.1)

prev_frame = None
last_motion = None
motion_filename = None
motion_file = None

frame_size = camera.resolution
fourcc = cv2.cv.CV_FOURCC(*"XVID")

for frame in camera.capture_continuous(rawCapture, format="bgr",use_video_port=True):
image = frame.array



frame_gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
frame_gray = cv2.GaussianBlur(frame_gray, (21, 21), 0)



if have_motion(prev_frame, frame_gray):
if motion_file is None:
now = datetime.now()
motion_filename = now.strftime("%Y_%m_%d_%H_%M_%S_MOTION.h264")
motion_file = cv2.VideoWriter(motion_filename, fourcc, 20.0, frame_size)
last_motion = time.time()
print "Motion!", last_motion

if motion_file is not None:
motion_file.write(image)
print 'Saving...'
print now
print time.time() - last_motion
if time.time() - last_motion > 3:
motion_file.release()
motion_file = None
print 'Saved'
print motion_filename
break


prev_frame = frame_gray
cv2.imshow('frame', image)
rawCapture.truncate(0)

if cv2.waitKey(1) & 0xFF == ord('q'):
cv2.destroyAllWindows()
break

Answer

I solved this by changing the codec from

fourcc = cv2.cv.CV_FOURCC(*"XVID")

to

fourcc = cv2.cv.CV_FOURCC(*"MPV4")

and by changing

motion_filename = now.strftime("%Y_%m_%d_%H_%M_%S_MOTION.h264")

to

motion_filename = now.strftime("%Y_%m_%d_%H_%M_%S_MOTION.avi")
Comments