miscellaneous other changes to make audio rendering work

Many changes were made throughout the codebase to support audio, these are
most of the small changes necessary.

The audio support still is not perfect. I still need to write in resampling
support. After that it should work correctly with all audio types.

app/node/input/media/audio/audio.cpp

@@ -26,22 +26,17 @@ QString AudioInput::Description()
   return tr("Import an audio footage stream.");
 }
 
-QVariant AudioInput::Value(NodeOutput *)
+NodeOutput *AudioInput::samples_output()
 {
-  /*if (output == samples_output_) {
-    // Make sure decoder is set up
-    if (!SetupDecoder()) {
-      return 0;
-    }
+  return samples_output_;
+}
 
-    // Retrieve audio samples from decoder
-    frame_ = decoder_->Retrieve(in, out - in);
+QVariant AudioInput::Value(NodeOutput *output)
+{
+  if (output == samples_output_) {
+    // Simple passthrough from footage input
+    return footage_input_->value();
+  }
 
-    QByteArray samples;
-    samples.resize(frame_->audio_params().samples_to_bytes(frame_->sample_count()));
-    memcpy(samples.data(), frame_->data(), static_cast<size_t>(samples.size()));
-    return samples;
-  }*/
-
-  return 0;
+  return MediaInput::Value(output);
 }

app/node/input/media/audio/audio.h

@@ -13,6 +13,8 @@ public:
   virtual QString Category() override;
   virtual QString Description() override;
 
+  NodeOutput* samples_output();
+
 protected:
   virtual QVariant Value(NodeOutput* output) override;
 

app/node/input/media/video/video.h

@@ -27,7 +27,6 @@ public:
   //virtual void Hash(QCryptographicHash *hash, NodeOutput* from, const rational &time) override;
 
 protected:
-  //virtual QVariant Value(NodeOutput* output, const rational& in, const rational& out) override;
 
 private:
   NodeInput* matrix_input_;