// Get the GPS box location
public static GPSBox GetGPS(string _file, long _moov)
{
GPSBox box = new GPSBox();
try
{
// Open the file in Read mode
FileStream fin = new FileStream(_file, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
// Seek to the end of the MOOV box
Streams.Seek(fin, _moov + 8);
// Get the first sub box size and type
int sub_box_size = (int)Streams.ReadUInt(fin, true);
string sub_box_type = Streams.ReadString(fin, 4);
// Loop while the sub box type is not "GPS "
while (sub_box_type.ToString() != "gps ")
{
// Check for end of box
// If not at end, seek to the next box
if (!Streams.Seek(fin, sub_box_size - 8))
{
Log.WriteLine("ERROR", "File at " + _file + " does not contain valid GPS data!");
return(box);
}
// Get the next sub box size and type
sub_box_size = (int)Streams.ReadUInt(fin, true);
sub_box_type = Streams.ReadString(fin, 4);
}
long gps = fin.Position - 8;
fin.Close();
// Set box position and size
box.Pos = gps;
box.Size = sub_box_size;
return(box);
}
catch
{
// Unable to open file
return(box);
}
}
// Get the GPS data from the file
public static GPSDataList ReadGPS(string _file, GPSBox _gpsBox)
{
GPSDataList GPSDataList = new GPSDataList();
try
{
// Open the file in Read mode
FileStream fin = new FileStream(_file, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
// Seek to the end of the "GPS " boc
// Skip the first 16 'header' bits
Streams.Seek(fin, _gpsBox.Pos + 16);
int gps_read = 16;
// While we are reading in the sub box
while (gps_read < _gpsBox.Size - 8)
{
// Get the GPS box position and size
int gps_box_pos = (int)Streams.ReadUInt(fin, true);
int gps_box_size = (int)Streams.ReadUInt(fin, true);
// Update our position
gps_read = gps_read + 8;
// Save the current file seek position
long pos = fin.Position;
// Seek to this GPS data
fin.Seek(gps_box_pos, SeekOrigin.Begin);
// Get the GPS box, size, type and magic
int gps_box_size1 = (int)Streams.ReadUInt(fin, true);
string gps_box_type = Streams.ReadString(fin, 4);
string gps_box_magic = Streams.ReadString(fin, 4);
// Verify the read data is GPS data
if (gps_box_size != gps_box_size1 || gps_box_type != "free" || gps_box_magic != "GPS ")
{
// Log incorrect data format
Log.WriteLine("ERROR", "Box at position: " + gps_box_pos + " is not the expected format\r\n\t\t\t\t" +
"(Expected size: " + gps_box_size + ", Actual size: " + gps_box_size1 + ", " +
"Expected type: free, Actual type: " + gps_box_type + ", " +
"Expected magic: GPS , Actual magic: " + gps_box_magic + ")\r\n");
continue;
}
// Extract GPS data
int version = (int)Streams.ReadUInt(fin);
// Maybe able to identify firmware version with this
// Firmware 1.1 and 2.02 = 76
// Firmware 2.0 = 15344
// Firmware 2.01 - NOT COMPATIBLE, BUG IN FIRMWARE
if (version == 76)
{
// Firmware 1.1 or 2.02
fin.Seek(32, SeekOrigin.Current);
}
else if (version == 15344)
{
// Firmware 2.0
// Nothing to do
}
else
{
// Unknown Firmware Version
}
int hour = (int)Streams.ReadUInt(fin);
int minute = (int)Streams.ReadUInt(fin);
int second = (int)Streams.ReadUInt(fin);
int year = (int)Streams.ReadUInt(fin);
int month = (int)Streams.ReadUInt(fin);
int day = (int)Streams.ReadUInt(fin);
string active = Streams.ReadString(fin, 1);
string latitude_b = Streams.ReadString(fin, 1);
string longitude_b = Streams.ReadString(fin, 1);
string unknown2 = Streams.ReadString(fin, 1);
float latitude = Streams.ReadFloat(fin);
float longitude = Streams.ReadFloat(fin);
// Check the GPS had a fix
if (active == "A")
{
// Correct the speed during load
// 1 knot = 0.514444 m/s
float speed = Streams.ReadFloat(fin) * (float)0.514444;
DateTime dateTime;
if (!Enumerable.Range(1, 31).Contains(day))
{
// TODO: Calculate day from somewhere
// Firmware 1.1 has an issue with day, used to get it from file name?
}
// Create DateTime object
if (year != 0 && month != 0 && day != 0)
{
dateTime = new DateTime((year + 2000), month, day, hour, minute, second);
}
else
{
// Date not valid
dateTime = new DateTime(1);
continue;
}
// Change coordinate from DDDmm.mmmm format to traditional lat/long
double flatitude = GPSHelpers.FixCoordinates(latitude_b, latitude);
double flongitude = GPSHelpers.FixCoordinates(longitude_b, longitude);
// Create new GPSData object
GPSData gps = new GPSData();
gps.DateTime = dateTime;
gps.Speed = speed;
// Kalman filter the GPS data to remove jumps
Kalman k = new Kalman(gps.Speed);
k.Process(flatitude, flongitude, 9.9f, 1000);
gps.Latitude = k.get_lat();
gps.Longitude = k.get_lng();
if (lastLat != 0 && lastLong != 0)
{
gps.Distance = GPSHelpers.Distance(lastLat, lastLong, flatitude, flongitude);
gps.Heading = GPSHelpers.Heading(lastLat, lastLong, flatitude, flongitude);
}
lastLat = gps.Latitude;
lastLong = gps.Longitude;
if (!slowSpeed)
{
GPSDataList.FilteredGPSData.Add(gps);
}
GPSDataList.AllGPSData.Add(gps);
// Remove a few points when speed is low to stop jagged lines
if (speed <= 1)
{
slowSpeed = true;
}
else
{
slowSpeed = false;
}
}
else
{
Log.WriteVerboseLine("GPS Location is not locked. Trying next block.");
}
// Return to original file seek
fin.Seek(pos, SeekOrigin.Begin);
}
}
catch (Exception e)
{
// Unable to open file
Log.WriteLine("ERROR", "Unable to process file: " + _file);
Log.WriteLine("ERROR", e.Message.ToString());
}
return(GPSDataList);
}