* outputting empty son-array, if the requested channel cannot be gene…

…rated (because there are not enough channels). This is done, so that client-side javascript code does not break.

examples/test1.json

@@ -1,5 +1,10 @@
 {
   "_generator":"wav2json version 0.4 on Darwin (http://goo.gl/af7wg)",
+  "right":[],
+  "mid":[],
+  "side":[],
+  "min":[],
+  "max":[],
   "left": [0,0.5,0.87,1,0.87,0.5,0,0.5,0.87,0,0.87,0.5],
   "duration":0.000250
 }

src/wav2json.cpp

@@ -113,7 +113,7 @@ void compute_waveform(
 
   // filter out channels, that require more channels than the wav file has
   channels.erase(
-      std::remove_if(channels.begin(), channels.end(), [&wav](Options::Channel channel){
+      std::remove_if(channels.begin(), channels.end(), [&wav, &output_stream](Options::Channel channel){
           if ((channel == Options::MID  ||
                channel == Options::SIDE ||
                channel == Options::RIGHT||
@@ -122,6 +122,7 @@ void compute_waveform(
                wav.channels() == 1
           )
           {
+            output_stream << "  \"" << channel << "\":[]," << endl; // output empty array, so that existing client-code does not break
             std::cerr << "Warning: your trying to generate output for channel '" << channel << "', but the input has only one channel. removing requested channel." << std::endl;
             return true;
           }