gpscam_5inch_py3.py

""" Raspberry Pi + GPS Car Camera
Achieved with three threads:

1. Main thread -
       Start preview and recording.

2. GPS thread -
       Read GPS location.

3. Annotate thread -
       Put GPS location and datetime on image.
       Refresh every one second to simulate a running clock.

Should be coupled with a cron job which deletes old video clips,
to prevent disk from filling up.
"""

import picamera
from datetime import datetime
import threading
import time
import os
import sys
import gpsd

video_size = (640, 480)
preview_dimension = (160, 0, 640, 480)  # x, y, w, h
clip_directory = sys.argv[1]

def record(camera):
    def datetime_filename():
        while 1:
            yield (
                os.path.join(
                    clip_directory,
                    datetime.now().strftime('%Y%m%d-%H%M.h264')))

    def seconds_to_go():
        length = 15 * 60
        now = datetime.now()
        seconds = now.minute * 60 + now.second
        return length - seconds % length

    for filename in camera.record_sequence(datetime_filename()):
        camera.wait_recording(seconds_to_go())

latest_location = None

def gpsread():
    global latest_location

    gpsd.connect()
    while 1:
        try:
            packet = gpsd.get_current()
            latest_location = packet.position()
        except gpsd.NoFixError:
            latest_location = None
        finally:
            time.sleep(1)

# Separate annotation from GPS because I want to refresh the text
# once per second to give an illusion of a running clock.
def annotate(camera):
    def compose_text(dt, location):
        if location:
            lat, lon = location
            loctext = '{:.4f}{} {:.4f}{}'.format(
                            lat, 'N' if lat >= 0 else 'S',
                            lon, 'E' if lon >= 0 else 'W')
        else:
            loctext = '--lat-- --lon--'

        return dt.strftime('%Y-%m-%d %H:%M:%S ') + loctext

    global latest_location
    camera.annotate_text_size = 24
    while 1:
        camera.annotate_text = compose_text(datetime.now(),
                                            latest_location)
        time.sleep(1)


camera = picamera.PiCamera(resolution=video_size, framerate=30)
#camera.hflip = True
#camera.vflip = True
#camera.rotation = 90

gps_thread = threading.Thread(target=gpsread)
gps_thread.daemon = True
gps_thread.start()

annotate_thread = threading.Thread(target=annotate, args=[camera])
annotate_thread.daemon = True
annotate_thread.start()

camera.start_preview(fullscreen=False, window=preview_dimension)
record(camera)