image_to_shm.py

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#!/usr/bin/env python

import rospy
import os, shutil
from sensor_msgs.msg import Image


filenum = 0
MAXFILES = 100
PATH = "/dev/shm/rosimgframes"  # filename format: frame number (integer) only, with no extension
imgnum = 0


def cleanup():
        rospy.sleep(3)
        deletefiles()
        rospy.loginfo("image_to_shm quit")

                
def deletefiles():
        if os.path.isdir(PATH):
                try:
                        shutil.rmtree(PATH)
                except:
                        pass
        

def imgCallBack(data):
        global filenum, imgnum
        
        #  imgnum += 1
        #  if data.width > 640 and imgnum %2 == 0: # skip every other high res frame
                #  return 
        
        oldfile = PATH+"/"+str(filenum-MAXFILES)

        if os.path.exists(oldfile):
                os.remove(oldfile)
        
        f = open(PATH+"/"+str(filenum), "w")
        f.write(data.data)
        f.close()

        filenum += 1
        

deletefiles() 
os.mkdir(PATH)

rospy.init_node('image_to_shm', anonymous=False)
rospy.loginfo("image_to_shm init")
rospy.Subscriber(rospy.get_param('~camera_topic', 'usb_cam/image_raw'), Image, imgCallBack) 
rospy.on_shutdown(cleanup)
print "using topic: "+rospy.get_param('~camera_topic', 'usb_cam/image_raw')

rospy.spin()