person_detection/base_camera.py

import paho.mqtt.client as mqtt
import time
import os
import sys
import threading
import logging as log
from multiprocessing import Process, Queue, Value, Array, Lock

from roc import Roc
import config


class BaseCamera(object):
    process = {} # background process that reads frames from camera
    frame = {} # frame queue
    activity_counter = Value('i', 0)
    cameras = Array('i', [0]*len(config.cameras))
    lock = Lock()

    def __init__(self, device, user, password, mbrlow, mbrhigh, devicegroup, noroc):
        self.mqttBroker = "localhost"
        self.device = device
        self.mbrlow = mbrlow
        self.mbrhigh = mbrhigh
        self.devicegroup = devicegroup
        self.noroc = noroc
        self.roc = Roc(user, password)

        """Start the background camera process if it isn't running yet."""
        if BaseCamera.cameras[int(self.device)] == 0:
            BaseCamera.cameras[int(self.device)] = 1
            self.last_detected = None
            self.timer = None
            self.detected = False
            BaseCamera.frame[self.device] = Queue(100)
            self.set_resolution(self.device, "low")
            # start background frame process
            BaseCamera.process[self.device] = Process(target=self._process, args=(self.device))
            BaseCamera.process[self.device].start()
            # wait until frames are available
            _ = self.get_frame()
            log.info("Start camera {} feed to {}".format(self.device, self.client))

    def get_frame(self):
        """Return the current camera frame."""

        # blocks
        return BaseCamera.frame[self.device].get(block=True)

    def frames(self):
        """"Generator that returns frames from the camera."""
        raise NotImplementedError('Must be implemented by subclasses.')

    def _process(self, device):
        """Camera background process."""
        frames_iterator = self.frames()
        for frame in frames_iterator:
            BaseCamera.frame[device].put(frame, block=True)

        BaseCamera.process[device] = None

    def person_detected(self, num):
        self.last_detected = time.time()
        if not self.detected:
            BaseCamera.lock.acquire()
            BaseCamera.activity_counter.value += 1
            BaseCamera.lock.release()
            self.set_resolution_high()
            if not self.noroc:
                self.roc.set_mbr(self.devicegroup, self.mbrhigh)
            self.detected = True
            self.start_timer()

    def no_person_detected(self):
        self.detected = False
        self.timer = None
        BaseCamera.lock.acquire()
        BaseCamera.activity_counter.value -=1
        if BaseCamera.activity_counter.value <= 0:
            BaseCamera.activity_counter.value = 0
            self.set_resolution_low()
            if not self.noroc:
                self.roc.set_mbr(self.devicegroup, self.mbrlow)
        BaseCamera.lock.release()


    def start_timer(self):
        # log.info("Start timer for device {}".format(device))
        self.timer = threading.Timer(10.0, self.timer_expiry)
        self.timer.start()


    def set_resolution_high(self):
        for device in range(0, len(config.cameras)):
            self.set_resolution(str(device), "high")


    def set_resolution_low(self):
        for device in range(0, len(config.cameras)):
            self.set_resolution(str(device), "low")


    def set_resolution(self, device, level):
        log.info("Setting camera {} resolution to {}".format(device, level))
        client = mqtt.Client()
        client.connect(self.mqttBroker)
        client.publish("camera/" + str(5000 + int(device)), level)


    def timer_expiry(self):
        now = time.time()
        diff = now - self.last_detected
        log.debug("timer_expiry() - now:{}, last_detected:{}".format(now, self.last_detected))
        if diff > 5.0:
            self.no_person_detected()
        else:
            # Restart timer since person detected not too long back
            self.start_timer()