Support changing watermarking parameters using command line args.

Signed-off-by: Stefan Westerfeld <stefan@space.twc.de>

src/audiowmark.cc

@@ -7,6 +7,10 @@
 #include "fft.hh"
 #include "wavdata.hh"
 
+#include <assert.h>
+
+#include "config.h"
+
 using std::string;
 using std::vector;
 using std::complex;
@@ -14,15 +18,144 @@ using std::min;
 
 namespace Params
 {
-  static constexpr int frame_size      = 1024;
-  static constexpr int frames_per_bit  = 4;
-  static constexpr int bands_per_frame = 30;
-  static constexpr int max_band        = 100;
-  static constexpr int min_band        = 20;
-  static constexpr double water_delta  = 0.015; // strength of the watermark
-  static constexpr double pre_scale    = 0.75;  // rescale the signal to avoid clipping after watermark is added
+  static size_t frame_size   = 1024;
+  static int frames_per_bit  = 4;
+  static int bands_per_frame = 30;
+  static int max_band        = 100;
+  static int min_band        = 20;
+  static double water_delta  = 0.015; // strength of the watermark
+  static double pre_scale    = 0.75;  // rescale the signal to avoid clipping after watermark is added
+}
+
+void
+print_usage()
+{
+  printf ("usage: audiowmark <command> [ <args>... ]\n");
+  printf ("\n");
+  printf ("Commands:\n");
+  printf ("  * create a watermarked wav file with a message\n");
+  printf ("    audiowmark add <input_wav> <watermarked_wav> <message_hex>\n");
+  printf ("\n");
+  printf ("  * blind decoding (retrieve message without original file)\n");
+  printf ("    audiowmark get <watermarked_wav>\n");
+  printf ("\n");
+  printf ("  * compute bit error rate for blind decoding\n");
+  printf ("    audiowmark cmp <watermarked_wav> <message_hex>\n");
+  printf ("\n");
+  printf ("  * retrieve message with original file\n");
+  printf ("    audiowmark get-delta <input_wav> <watermarked_wav>\n");
+  printf ("\n");
+  printf ("  * compute bit error rate for decoding with original file\n");
+  printf ("    audiowmark cmp-delta <input_wav> <watermarked_wav> <message_hex>\n");
+  printf ("\n");
+  printf ("Global options:\n");
+  printf ("  --frame-size          frame size (must be power of 2)     [%zd]\n", Params::frame_size);
+  printf ("  --frames-per-bit      number of frames per bit            [%d]\n",  Params::frames_per_bit);
+  printf ("  --water-delta         set watermarking delta              [%.4f]\n", Params::water_delta);
+  printf ("  --pre-scale           set scaling used for normalization  [%.3f]\n", Params::pre_scale);
 }
 
+static bool
+check_arg (uint         argc,
+           char        *argv[],
+           uint        *nth,
+           const char  *opt,		    /* for example: --foo */
+           const char **opt_arg = nullptr)  /* if foo needs an argument, pass a pointer to get the argument */
+{
+  assert (opt != nullptr);
+  assert (*nth < argc);
+
+  const char *arg = argv[*nth];
+  if (!arg)
+    return false;
+
+  uint opt_len = strlen (opt);
+  if (strcmp (arg, opt) == 0)
+    {
+      if (opt_arg && *nth + 1 < argc)	  /* match foo option with argument: --foo bar */
+        {
+          argv[(*nth)++] = nullptr;
+          *opt_arg = argv[*nth];
+          argv[*nth] = nullptr;
+          return true;
+        }
+      else if (!opt_arg)		  /* match foo option without argument: --foo */
+        {
+          argv[*nth] = nullptr;
+          return true;
+        }
+      /* fall through to error message */
+    }
+  else if (strncmp (arg, opt, opt_len) == 0 && arg[opt_len] == '=')
+    {
+      if (opt_arg)			  /* match foo option with argument: --foo=bar */
+        {
+          *opt_arg = arg + opt_len + 1;
+          argv[*nth] = nullptr;
+          return true;
+        }
+      /* fall through to error message */
+    }
+  else
+    return false;
+
+  print_usage();
+  exit (1);
+}
+
+void
+parse_options (int   *argc_p,
+               char **argv_p[])
+{
+  uint argc = *argc_p;
+  char **argv = *argv_p;
+  unsigned int i, e;
+
+  for (i = 1; i < argc; i++)
+    {
+      const char *opt_arg;
+      if (strcmp (argv[i], "--help") == 0 ||
+          strcmp (argv[i], "-h") == 0)
+	{
+	  print_usage();
+	  exit (0);
+	}
+      else if (strcmp (argv[i], "--version") == 0 || strcmp (argv[i], "-v") == 0)
+	{
+	  printf ("audiowmark %s\n", VERSION);
+	  exit (0);
+	}
+      else if (check_arg (argc, argv, &i, "--frame-size", &opt_arg))
+	{
+          Params::frame_size = atoi (opt_arg);
+	}
+      else if (check_arg (argc, argv, &i, "--frames-per-bit", &opt_arg))
+	{
+          Params::frames_per_bit = atoi (opt_arg);
+	}
+      else if (check_arg (argc, argv, &i, "--water-delta", &opt_arg))
+	{
+          Params::water_delta = atof (opt_arg);
+	}
+      else if (check_arg (argc, argv, &i, "--pre-scale", &opt_arg))
+	{
+          Params::pre_scale = atof (opt_arg);
+	}
+    }
+
+  /* resort argc/argv */
+  e = 1;
+  for (i = 1; i < argc; i++)
+    if (argv[i])
+      {
+        argv[e++] = argv[i];
+        if (i >= e)
+          argv[i] = nullptr;
+      }
+  *argc_p = e;
+}
+
+
 inline double
 window_cos (double x) /* von Hann window */
 {
@@ -203,7 +336,7 @@ watermark_frame (const vector<float>& input_frame, int f, int data_bit)
   vector<float> fft_delta_out = ifft (fft_delta_spect);
 
   vector<float> synth_window (Params::frame_size);
-  for (int i = 0; i < Params::frame_size; i++)
+  for (size_t i = 0; i < Params::frame_size; i++)
     {
       const double threshold = 0.2;
 
@@ -520,6 +653,8 @@ get_snr (const string& origfile, const string& wmfile)
 int
 main (int argc, char **argv)
 {
+  parse_options (&argc, &argv);
+
   string op = (argc >= 2) ? argv[1] : "";
 
   if (op == "add" && argc == 5)