improve duration precision

src/main.cpp

@@ -65,12 +65,12 @@ int main(int argc, char* argv[])
     // open sound file
     SndfileHandle wav(options.input_file_name.c_str());
 
-	// output sound duration
-	if (i == 0) {
-		ofs << "  \"duration\":" << wav.frames()/wav.samplerate() << "," << std::endl;	  
-	}
+	// // output sound duration
+	// if (i == 0) {
+	// 	ofs << "  \"duration\":" << wav.frames()/(float)wav.samplerate() << "," << std::endl;	  
+	// }
 
-    // handle error
+    // Handle error
     if ( wav.error() )
     {
         cerr << "Error opening audio file '" << options.input_file_name << "'" << endl;
@@ -82,7 +82,7 @@ int main(int argc, char* argv[])
 
     ofs << "  \"" << channel << "\":";
 
-    compute_waveform(
+    float sampleDur = compute_waveform(
       wav,
       ofs,
       options.samples,
@@ -93,8 +93,14 @@ int main(int argc, char* argv[])
       progress_callback
     );
 
-    if (i != options.channels.size()-1) //only write comma, if this is not the last entry
-      ofs << "," << std::endl;
+    // if (i != options.channels.size()-1) //only write comma, if this is not the last entry
+    //   ofs << "," << std::endl;
+
+	ofs << "," << std::endl;
+	if (i == options.channels.size()-1) {
+		ofs << std::endl;
+		ofs << "  \"duration\":" << sampleDur;
+	}
   }
 
   ofs << std::endl << "}" << std::endl;

src/wav2json.cpp

@@ -80,7 +80,7 @@ T compute_sample(const std::vector<T>& block, int i, int n_channels, Options::Ch
 /*
   compute the waveform of the supplied audio-file and store it into out_image.
 */
-void compute_waveform(
+float compute_waveform(
   const SndfileHandle& wav,
   std::ostream& output_stream,
   size_t samples,
@@ -134,9 +134,13 @@ void compute_waveform(
   */
   for (size_t x = 0; x < samples; ++x)
   {
-    // read frames
+	  // read frames
+	  //int pos = (int)(x*wav.frames()/samples);
+	  //const_cast<SndfileHandle&>(wav).seek(pos, SEEK_SET);
     sf_count_t n = const_cast<SndfileHandle&>(wav).readf(&block[0], frames_per_pixel) * wav.channels();
     assert(n <= (sf_count_t)block.size());
+	// std::cout << "frames: " << const_cast<SndfileHandle&>(wav).seek(0, SEEK_CUR) << std::endl;
+
 
     // find min and max
     sample_type max(0);
@@ -159,13 +163,20 @@ void compute_waveform(
     if ( x%(progress_divisor) == 0 )
     {
       if ( progress_callback && !progress_callback( 100*x/samples ) )
-          return;
+          return 0;
     }
   }
 
   // call the progress callback
   if ( progress_callback && !progress_callback( 100 ) )
-    return;
+    return 0;
 
   output_stream << "]";
+  std::cout << "frames: " << const_cast<SndfileHandle&>(wav).seek(0, SEEK_CUR) << std::endl;
+  std::cout << "frames2: " << frames_per_pixel*samples << std::endl;
+  std::cout << "sample duration: " << const_cast<SndfileHandle&>(wav).seek(0, SEEK_CUR)/wav.samplerate() << std::endl;
+  std::cout << "sample duration2: " << (frames_per_pixel*samples)/(float)wav.samplerate() << std::endl;
+  std::cout << "total frames " << wav.frames() << std::endl;
+  std::cout << "total duration: " <<  wav.frames()/(float)wav.samplerate()<< std::endl;
+  return (frames_per_pixel*samples)/(float)wav.samplerate();
 }

src/wav2json.hpp

@@ -7,7 +7,7 @@
     typedef bool (*progress_callback_t)(size_t progress);
 #endif /* __OBJC__ */
 
-void compute_waveform(
+float compute_waveform(
   const SndfileHandle& wav,
   std::ostream& output_stream,
   size_t samples,