Add AudioContext to AudioSubDocument

The AudioContext will hold all the data from the audio file / the audio streams in the files.

• Fix the get audio from some files (didn't not handle multiple stream files)
• Remove last C code references
• It's working for audio files (not for video files used as audio able files)
• Add the Lib sub-folder, see the CONTRIBUTING.md file for dependencies between all the sub-folders

src/UI/AudioVisualizer.cc

@@ -29,8 +29,8 @@ AudioVisualizer::AudioVisualizer(AudioContext::StreamPtr stream, QWidget *parent
         stream->decodeData();
     }
 
-    double *data = stream->getDecodedData();
-    if (data == nullptr)
+    double *decodedData = stream->getDecodedData();
+    if (decodedData == nullptr)
         throw std::logic_error("the passed stream is not decoded");
 
     const size_t size     = stream->getDecodedDataSize();
@@ -57,7 +57,7 @@ AudioVisualizer::AudioVisualizer(AudioContext::StreamPtr stream, QWidget *parent
     for (size_t x = 0, i = 0; i < size - height; i += decalage, ++x) {
 #pragma omp parallel for
         for (size_t j = 0; j < height; j++) {
-            const double curr_dat = data[i + j];
+            const double curr_dat = decodedData[i + j];
             const double window_modifier =
                 (1 - cos(2 * M_PI * static_cast<double>(j) / static_cast<double>(height - 1))) / 2;
             float value = static_cast<float>(window_modifier * curr_dat);