SRC: audiowmark.cc: write --json output into an output file

Restore the ability to print out detection and debug info, while
writing the detection results into a separate file in JSON format.
Signed-off-by: Tim Janik <timj@gnu.org>

src/audiowmark.cc

@@ -58,7 +58,7 @@ print_usage()
   printf ("\n");
   printf ("Global options:\n");
   printf ("  --strength <s>        set watermark strength              [%.6g]\n", Params::water_delta * 1000);
-  printf ("  --json                produce JSON output\n");
+  printf ("  --json <file>         write JSON results into file\n");
   printf ("  --linear              disable non-linear bit storage\n");
   printf ("  --short <bits>        enable short payload mode\n");
   printf ("  --key <file>          load watermarking key from file\n");
@@ -457,9 +457,9 @@ parse_shared_options (ArgParser& ap)
     {
       Params::water_delta = f / 1000;
     }
-  if (ap.parse_opt ("--json"))
+  if (ap.parse_opt ("--json", s))
     {
-      Params::json_output = true;
+      Params::json_output = s;
     }
   if (ap.parse_opt  ("--key", s))
     {

src/wmcommon.cc

@@ -22,7 +22,6 @@
 
 int    Params::frames_per_bit  = 2;
 double Params::water_delta     = 0.01;
-bool   Params::json_output     = false;
 bool   Params::mix             = true;
 bool   Params::hard            = false; // hard decode bits? (soft decoding is better)
 bool   Params::snr             = false; // compute/show snr while adding watermark
@@ -44,6 +43,7 @@ RawFormat Params::raw_output_format;
 
 int    Params::hls_bit_rate = 0;
 
+std::string Params::json_output;
 std::string Params::input_label;
 std::string Params::output_label;
 

src/wmcommon.hh

@@ -40,7 +40,7 @@ public:
   static constexpr int min_band          = 20;
 
   static           double water_delta;
-  static           bool json_output;
+  static           std::string json_output;
   static           bool mix;
   static           bool hard;                      // hard decode bits? (soft decoding is better)
   static           bool snr;                       // compute/show snr while adding watermark

src/wmget.cc

@@ -167,8 +167,14 @@ public:
     patterns.push_back (p);
   }
   void
-  print_json (const WavData& wav_data)
+  print_json (const WavData& wav_data, const std::string &json_file)
   {
+    FILE *outfile = fopen (json_file.c_str(), "w");
+    if (!outfile)
+      {
+        perror (("audiowmark: failed to open \"" + json_file + "\":").c_str());
+        exit (127);
+      }
     std::stable_sort (patterns.begin(), patterns.end(), [](const Pattern& p1, const Pattern& p2) {
       const int all1 = p1.type == Type::ALL;
       const int all2 = p2.type == Type::ALL;
@@ -178,18 +184,18 @@ public:
         return p1.sync_score.index < p2.sync_score.index;
     });
     const size_t time_length = (wav_data.samples().size() / wav_data.n_channels() + wav_data.sample_rate()/2) / wav_data.sample_rate();
-    printf ("{ \"length\": \"%ld:%02ld\",\n", time_length / 60, time_length % 60);
-    printf ("  \"matches\": [\n");
+    fprintf (outfile, "{ \"length\": \"%ld:%02ld\",\n", time_length / 60, time_length % 60);
+    fprintf (outfile, "  \"matches\": [\n");
     int nth = 0;
     for (const auto& pattern : patterns)
       {
         if (nth++ != 0)
-          printf (",\n");
+          fprintf (outfile, ",\n");
         if (pattern.type == Type::ALL) /* this is the combined pattern "all" */
           {
-            printf ("    { \"pos\": \"0:00\", \"bits\": \"%s\", \"quality\": %.5f, \"error\": %.6f, \"clip\": false, \"type\": \"ALL\" }",
-                    bit_vec_to_str (pattern.bit_vec).c_str(),
-                    pattern.sync_score.quality, pattern.decode_error);
+            fprintf (outfile, "    { \"pos\": \"0:00\", \"bits\": \"%s\", \"quality\": %.5f, \"error\": %.6f, \"clip\": false, \"type\": \"ALL\" }",
+                     bit_vec_to_str (pattern.bit_vec).c_str(),
+                     pattern.sync_score.quality, pattern.decode_error);
           }
         else
           {
@@ -201,14 +207,15 @@ public:
               case ConvBlockType::ab: blockc = "\"AB\"";      break;
               }
             const int seconds = pattern.sync_score.index / Params::mark_sample_rate;
-            printf ("    { \"pos\": \"%d:%02d\", \"bits\": \"%s\", \"quality\": %.5f, \"error\": %.6f, \"clip\": %s, \"type\": %s }",
-                    seconds / 60, seconds % 60,
-                    bit_vec_to_str (pattern.bit_vec).c_str(),
-                    pattern.sync_score.quality, pattern.decode_error,
-                    pattern.type == Type::CLIP ? "true" : "false", blockc);
+            fprintf (outfile, "    { \"pos\": \"%d:%02d\", \"bits\": \"%s\", \"quality\": %.5f, \"error\": %.6f, \"clip\": %s, \"type\": %s }",
+                     seconds / 60, seconds % 60,
+                     bit_vec_to_str (pattern.bit_vec).c_str(),
+                     pattern.sync_score.quality, pattern.decode_error,
+                     pattern.type == Type::CLIP ? "true" : "false", blockc);
           }
       }
-    printf (" ]\n}\n");
+    fprintf (outfile, " ]\n}\n");
+    fclose (outfile);
   }
   void
   print()
@@ -619,11 +626,12 @@ decode_and_report (const WavData& wav_data, const string& orig_pattern)
   ClipDecoder clip_decoder;
   clip_decoder.run (wav_data, result_set);
 
-  if (Params::json_output)
-    {
-      result_set.print_json (wav_data);
-    }
-  else if (!orig_pattern.empty())
+  if (!Params::json_output.empty())
+    result_set.print_json (wav_data, Params::json_output);
+
+  result_set.print();
+
+  if (!orig_pattern.empty())
     {
       int match_count = result_set.print_match_count (orig_pattern);