Raspberry Pi Car Cam overlaid with OBD data

#www.stuffaboutcode.com
#Create SRT file from odb data file

#import modules
import datetime
import time

#Class to manage creating SRT File
class CreateSRT:
    def __init__(self, srtFileName):
        #Open subtitle file
        self.srtFile = open(srtFileName, "w")
        self.subTitleCount = 0

    def addSubTitle(self, startTime, endTime, text):
        #Add subtitle to file
        # increment count
        self.subTitleCount += 1
        # write count
        self.srtFile.write(str(self.subTitleCount) + "\n")
        # write from and to time
        self.srtFile.write("{0:02d}".format(startTime.seconds / 3600) + ":" +
                           "{0:02d}".format((startTime.seconds % 3600) / 60) + ":" +
                           "{0:02d}".format((startTime.seconds % 3600) % 60) + "," +
                           "{0:03d}".format(startTime.microseconds / 1000) +
                           " --> " +
                           "{0:02d}".format(endTime.seconds / 3600) + ":" +
                           "{0:02d}".format((endTime.seconds % 3600) / 60) + ":" +
                           "{0:02d}".format((endTime.seconds % 3600) % 60) + "," +
                           "{0:03d}".format(endTime.microseconds / 1000) + "\n")
        # write subtitle text
        self.srtFile.write(text + "\n")

    def close(self):
        self.srtFile.close()

def stripOBDData(obdDataLine):
    obdDataItems = obdDataLine.split(",")
    return obdDataItems[0], obdDataItems[1], obdDataItems[2], obdDataItems[3]

def getSubTitleText(subTitleOutput):
    subTitleText = ""
    for subTitle in subTitleOutput:
        subTitleText += subTitle + " " + subTitleOutput[subTitle]
    return subTitleText

#data to drive program
obdDataFileName = "22_49_0_obd.log"
srtFileName = "22_49_0.srt"
#the time the video started, using 1/1/1900, as only have time for obd data
videoStartTime = datetime.datetime(1900, 1, 1, 22,48,55,312014)
subTitleOutput = {"           Vehicle Speed": "\n",
                  "              Engine RPM": "\n",
                  "       Throttle Position": "\n",
                  "     Coolant Temperature": "\n"}

if __name__ == "__main__":
    #Open OBD data file
    obdDataFile = open(obdDataFileName)
    # read in obd data
    obdData = obdDataFile.readlines()
    obdDataFile.close()
    #Create SRT file object
    srtFile = CreateSRT(srtFileName)
    lastSRTTime = datetime.timedelta(0,0,0,1)
    # loop through obd data
    for obdDataLine in obdData:
        # get data items about of the obd data string
        sensorTime, sensorName, sensorValue, SensorUnit = stripOBDData(obdDataLine)
        # is the sensor in the subtitle output?
        if (sensorName in subTitleOutput.keys()):
            # get sensor time as object
            sensorTime = datetime.datetime.strptime(sensorTime, "%H:%M:%S.%f")
            # get the difference between the start of the video and sensor time
            timeDiff = sensorTime - videoStartTime
            # occasionally the sensors are not written in cronological order!
            # no idea way, but i only want ones which are after the last one I saw
            if timeDiff > lastSRTTime:
                #Found a new sensor so the subtitle has changed
                # create the previous subtitle
                srtFile.addSubTitle(lastSRTTime, timeDiff, getSubTitleText(subTitleOutput))
                # update the subtitle output and store the last time
                # if the sensor has a "." take only the first 1 digits after the point
                if sensorValue.find(".") != -1: sensorValue = sensorValue[:sensorValue.find(".") + 2]
                subTitleOutput[sensorName] = sensorValue + " " + SensorUnit
                # add one millisecond to the last subtitle time so the next one doesn't appear exactly as the last one disappeared!
                lastSRTTime = timeDiff + datetime.timedelta(0,0,0,1)

    #close srt file class
    srtFile.close()