Support --block argument to set the reorder block size.

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

src/audiowmark.cc

@@ -15,11 +15,13 @@ using std::string;
 using std::vector;
 using std::complex;
 using std::min;
+using std::max;
 
 namespace Params
 {
   static size_t frame_size   = 1024;
   static int frames_per_bit  = 4;
+  static int block           = 1;
   static int bands_per_frame = 30;
   static int max_band        = 100;
   static int min_band        = 20;
@@ -51,6 +53,7 @@ print_usage()
   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 ("  --block               set bit reordering block size       [%d]\n",  Params::block);
   printf ("  --water-delta         set watermarking delta              [%.4f]\n", Params::water_delta);
   printf ("  --pre-scale           set scaling used for normalization  [%.3f]\n", Params::pre_scale);
 }
@@ -133,6 +136,10 @@ parse_options (int   *argc_p,
 	{
           Params::frames_per_bit = atoi (opt_arg);
 	}
+      else if (check_arg (argc, argv, &i, "--block", &opt_arg))
+	{
+          Params::block = atoi (opt_arg);
+	}
       else if (check_arg (argc, argv, &i, "--water-delta", &opt_arg))
 	{
           Params::water_delta = atof (opt_arg);
@@ -378,12 +385,22 @@ add_watermark (const string& infile, const string& outfile, const string& bits)
 
   printf ("loading %s\n", infile.c_str());
 
-  WavData wav_data;
-  if (!wav_data.load (infile))
+  WavData xwav_data;
+  if (!xwav_data.load (infile))
     {
-      fprintf (stderr, "audiowmark: error loading %s: %s\n", infile.c_str(), wav_data.error_blurb());
+      fprintf (stderr, "audiowmark: error loading %s: %s\n", infile.c_str(), xwav_data.error_blurb());
       return 1;
     }
+
+  size_t block_size = Params::block * Params::frames_per_bit * Params::frame_size * xwav_data.n_channels();
+
+  /* we truncate the audio down to a multiple of the reorder block size - for a production quality
+   * implemenation this is not good enough, but it is ok for comparing error rates
+   */
+  vector<float> in_signal (xwav_data.samples().begin(), xwav_data.samples().end() - xwav_data.n_values() % block_size);
+  WavData wav_data (in_signal, xwav_data.n_channels(), xwav_data.mix_freq(), xwav_data.bit_depth());
+  printf ("input signal frames: before = %f\n", double (xwav_data.n_values()) / block_size);
+  printf ("input signal frames: after  = %f\n", double (wav_data.n_values()) / block_size);
   vector<float> out_signal (wav_data.n_values());
   printf ("channels: %d, samples: %zd, mix_freq: %f\n", wav_data.n_channels(), wav_data.n_values(), wav_data.mix_freq());