exif fixes.

supply default speed_ref for the reader.
report undefined alt_refs in the reader.
correctly output the gps tag version tag in the writer.
use the correct value for the altitude reference tag in the writer so that negative altitudes are correctly written.

diff --git a/gpsbabel/exif.cc b/gpsbabel/exif.cc
index 848c76d0809d9d0694c4238648b24d645196d34c..5e906b01312855f665e6a40a07f8b808ae5c1d8c 100644 (file)
--- a/gpsbabel/exif.cc
+++ b/gpsbabel/exif.cc
@@ -20,6 +20,14 @@
 
  */
 
+/*
+ * Exif specifications can be found at
+ * 2012, version 2.3: http://www.cipa.jp/english/hyoujunka/kikaku/pdf/DC-008-2012_E.pdf
+ * 2010, version 2.3: http://www.cipa.jp/english/hyoujunka/kikaku/pdf/DC-008-2010_E.pdf
+ * 2002, version 2.2: http://www.exif.org/Exif2-2.PDF
+ * 1998, version 2.1: http://www.exif.org/Exif2-1.PDF
+ */
+
 #include <ctype.h>
 #include <math.h>
 #include <stdlib.h>
@@ -134,6 +142,8 @@ static char* exif_fout_name;
 
 static char* opt_filename, *opt_overwrite, *opt_frame, *opt_name;
 
+static gbuint8 writer_gps_tag_version[4] = {2, 0, 0, 0};
+
 arglist_t exif_args[] = {
   { "filename", &opt_filename, "Set waypoint name to source filename", "Y", ARGTYPE_BOOL, ARG_NOMINMAX },
   { "frame", &opt_frame, "Time-frame (in seconds)", "10", ARGTYPE_INT, "0", NULL },
@@ -676,7 +686,7 @@ exif_waypt_from_exif_app(exif_app_t* app)
   char lat_ref = '\0';
   char lon_ref = '\0';
   char alt_ref = 0;
-  char speed_ref = '\0';
+  char speed_ref = 'K';
   char* datum = NULL;
   char mode = '\0';
   double gpsdop = unknown_alt;
@@ -780,7 +790,7 @@ exif_waypt_from_exif_app(exif_app_t* app)
 
   if (alt != unknown_alt) {
     double sign;
-    switch (alt_ref != 0) {
+    switch (alt_ref) {
     case 0:
       sign = 1.0;
       break;
@@ -790,7 +800,7 @@ exif_waypt_from_exif_app(exif_app_t* app)
       break;
 
     default:
-      warning(MYNAME ": Invalid GPSAltitudeRef (%d)! Using 0 (= Sea level).\n", alt_ref);
+      warning(MYNAME ": Invalid GPSAltitudeRef (%d)! Using default value 0 (= Sea level).\n", alt_ref);
       sign = 1.0;
     }
     wpt->altitude = sign * alt;
@@ -1255,7 +1265,7 @@ exif_write_apps(void)
       exif_tag_t* tag;
 
       exif_put_long(IFD0, IFD0_TAG_GPS_IFD_OFFS, 0, 0);
-      exif_put_long(GPS_IFD, GPS_IFD_TAG_VERSION, 0, 2);
+      exif_put_value(GPS_IFD, GPS_IFD_TAG_VERSION, EXIF_TYPE_BYTE, 4, 0, writer_gps_tag_version);
 
       sortqueue(&exif_app->ifds, exif_sort_ifds_cb);
 
@@ -1424,7 +1434,6 @@ exif_wr_deinit(void)
 static void
 exif_write(void)
 {
-  char alt_ref = 0;
   time_t frame;
 
   exif_wpt_ref = NULL;
@@ -1468,7 +1477,7 @@ exif_write(void)
     const waypoint* wpt = exif_wpt_ref;
 
     exif_put_long(IFD0, IFD0_TAG_GPS_IFD_OFFS, 0, 0);
-    exif_put_long(GPS_IFD, GPS_IFD_TAG_VERSION, 0, 2);
+    exif_put_value(GPS_IFD, GPS_IFD_TAG_VERSION, EXIF_TYPE_BYTE, 4, 0, writer_gps_tag_version);
     exif_put_str(GPS_IFD, GPS_IFD_TAG_DATUM, "WGS-84");
 
     exif_put_str(GPS_IFD, GPS_IFD_TAG_LATREF, wpt->latitude < 0 ? "S" : "N");
@@ -1480,6 +1489,12 @@ exif_write(void)
       exif_remove_tag(GPS_IFD, GPS_IFD_TAG_ALT);
       exif_remove_tag(GPS_IFD, GPS_IFD_TAG_ALTREF);
     } else {
+      gbuint8 alt_ref;
+      if (wpt->altitude >= 0.0) {
+        alt_ref = 0;
+      } else {
+        alt_ref = 1;
+      }
       exif_put_value(GPS_IFD, GPS_IFD_TAG_ALTREF, EXIF_TYPE_BYTE, 1, 0, &alt_ref);
       exif_put_double(GPS_IFD, GPS_IFD_TAG_ALT, 0, wpt->altitude);
     }