implemented preliminary pre-cacher for audio

FFmpegDecoder now implements an "indexer" for audio, which actually just
extracts the raw PCM audio from an audio codec and saves it to disk

app/render/audio/audioparams.cpp

@@ -52,7 +52,7 @@ int AudioRenderingParams::time_to_bytes(const rational &time) const
 {
   Q_ASSERT(is_valid());
 
-  return qFloor(time.toDouble() * sample_rate()) * channel_count() * sample_size();
+  return qFloor(time.toDouble() * sample_rate()) * channel_count() * bytes_per_sample();
 }
 
 int AudioRenderingParams::channel_count() const
@@ -60,7 +60,7 @@ int AudioRenderingParams::channel_count() const
   return av_get_channel_layout_nb_channels(channel_layout());
 }
 
-int AudioRenderingParams::sample_size() const
+int AudioRenderingParams::bytes_per_sample() const
 {
   switch (format_) {
   case olive::SAMPLE_FMT_U8:
@@ -71,6 +71,7 @@ int AudioRenderingParams::sample_size() const
   case olive::SAMPLE_FMT_FLT:
     return 4;
   case olive::SAMPLE_FMT_DBL:
+  case olive::SAMPLE_FMT_S64:
     return 8;
   case olive::SAMPLE_FMT_INVALID:
   case olive::SAMPLE_FMT_COUNT:
@@ -80,6 +81,11 @@ int AudioRenderingParams::sample_size() const
   return 0;
 }
 
+int AudioRenderingParams::bits_per_sample() const
+{
+  return bytes_per_sample() * 8;
+}
+
 bool AudioRenderingParams::is_valid() const
 {
   return (sample_rate() > 0

app/render/audio/audioparams.h

@@ -30,7 +30,8 @@ public:
 
   int time_to_bytes(const rational& time) const;
   int channel_count() const;
-  int sample_size() const;
+  int bytes_per_sample() const;
+  int bits_per_sample() const;
   bool is_valid() const;
 
   const olive::SampleFormat& format() const;

app/render/video/videorenderer.cpp

@@ -344,14 +344,27 @@ void VideoRendererProcessor::ThreadCallback(RenderTexturePtr texture, const rati
 
   // If the connected output is using this time, signal it to update
   if (last_time_requested_ == time) {
+
     copy_buffer_.Bind();
-    texture->Bind();
 
-    QOpenGLContext::currentContext()->functions()->glViewport(0, 0, master_texture_->width(), master_texture_->height());
+    QOpenGLFunctions* f = QOpenGLContext::currentContext()->functions();
 
-    olive::gl::Blit(copy_pipeline_);
+    if (texture == nullptr) {
+
+      // No texture, clear the master and push it
+      f->glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
+      f->glClear(GL_COLOR_BUFFER_BIT);
+
+    } else {
+      texture->Bind();
+
+      f->glViewport(0, 0, master_texture_->width(), master_texture_->height());
+
+      olive::gl::Blit(copy_pipeline_);
+
+      texture->Release();
+    }
 
-    texture->Release();
     copy_buffer_.Release();
 
     push_time_ = time;