Add very basic parsing code, will improve later

blackvue_gps.py

@@ -0,0 +1,94 @@
+"""
+Get GPS records out of BlackVue video. Currently outputs CSV files,
+with support for more formats added later.
+
+Usage:
+  blackvue_gps --to-csv <filename>
+
+"""
+import csv
+import os
+import re
+from collections import namedtuple
+
+import pynmea2
+from docopt import docopt
+from pynmea2 import ParseError
+
+import blackclue
+
+GPSPoint = namedtuple('GPSPoint', ['unix_ms', 'lat', 'lon'])
+
+
+def parse_blackvue_nmea(filename):
+    """
+    Parse a NMEA file as created by BlackVue, meaning there is a unix timestamp
+    in milliseconds before the NMEA string.
+
+    :param filename: the location of the BlackVue NMEA as string
+    :return: a list of GPSPoint
+    """
+    filename = filename.replace(".mp4", ".nmea")
+    records = []
+    with open(filename, 'r') as r:
+        for line in r.readlines():
+            if line.startswith('['):
+                # TODO make proper regex and less string slicing
+                unix_ms = re.findall(r'(?=\[).*(?=\])', line)[0][1:]
+                try:
+                    parsed_nmea = pynmea2.parse(line[len(unix_ms) + 2:])
+                    if hasattr(parsed_nmea, 'latitude'):
+                        lat, lon = parsed_nmea.latitude, parsed_nmea.longitude
+                        records.append(GPSPoint(unix_ms=unix_ms,
+                                                lat=lat,
+                                                lon=lon))
+                except ParseError:
+                    print('ParseError', line[len(unix_ms) + 2:])
+    return records
+
+
+def list_of_namedtuple_to_csv(list_of_tuples, outputfilename):
+    """
+    Write a list of namedtuples to a csv file.
+
+    :param list_of_tuples: a list of namedtuples of the same type
+    :param outputfilename: a target output filename
+    """
+    fields = []
+    if len(list_of_tuples) > 0:
+        fields = list_of_tuples[0]._fields
+    with open(outputfilename, 'w') as w:
+        csvwriter = csv.writer(w)
+        csvwriter.writerow(fields)
+        for row in list_of_tuples:
+            csvwriter.writerow(row)
+
+
+def main(**kwargs):
+    tocsv = kwargs['--to-csv']
+    filename = kwargs['<filename>']
+    if filename:
+        if os.path.isfile(filename):
+            records = parse_blackvue_nmea(filename=filename)
+            if tocsv:
+                outputfilename = filename.replace('.mp4', '.gps.csv')
+                list_of_namedtuple_to_csv(records, outputfilename)
+        elif os.path.isdir(filename):
+            foldername = filename
+            for filename in filter(lambda x: x.endswith('.mp4'),
+                                   os.listdir(foldername)):
+                blackclue.dump(file=[os.path.join(foldername, filename)],
+                               dump_embedded=True,
+                               dump_raw_blocks=False,
+                               extended_scan=False,
+                               verbose=False)
+                records = parse_blackvue_nmea(filename=os.path.join(
+                    foldername, filename))
+                if tocsv:
+                    outputfilename = filename.replace('.mp4', '.gps.csv')
+                    list_of_namedtuple_to_csv(records, os.path.join(
+                        foldername, outputfilename))
+
+
+if __name__ == "__main__":
+    main(**docopt(__doc__))