audiobackend: truncate PCM cache size when the length is reduced

app/render/backend/audio/audiobackend.cpp

@@ -85,6 +85,7 @@ void AudioBackend::ThreadCompletedCache(NodeDependency dep, NodeValueTable data,
       f.write(cached_samples.data(), copy_length);
 
       if (copy_length < length) {
+
         // Fill in remainder with silence
         QByteArray empty_space(length - copy_length, 0);
         f.write(empty_space);

app/render/backend/audiorenderbackend.cpp

@@ -36,12 +36,14 @@ void AudioRenderBackend::ConnectViewer(ViewerOutput *node)
 {
   connect(node, &ViewerOutput::AudioChangedBetween, this, &AudioRenderBackend::InvalidateCache);
   connect(node, &ViewerOutput::AudioGraphChanged, this, &AudioRenderBackend::QueueRecompile);
+  connect(node, &ViewerOutput::LengthChanged, this, &AudioRenderBackend::TruncateCache);
 }
 
 void AudioRenderBackend::DisconnectViewer(ViewerOutput *node)
 {
   disconnect(node, &ViewerOutput::AudioChangedBetween, this, &AudioRenderBackend::InvalidateCache);
   disconnect(node, &ViewerOutput::AudioGraphChanged, this, &AudioRenderBackend::QueueRecompile);
+  disconnect(node, &ViewerOutput::LengthChanged, this, &AudioRenderBackend::TruncateCache);
 }
 
 bool AudioRenderBackend::CompileInternal()
@@ -192,6 +194,17 @@ void AudioRenderBackend::ConformUpdated(Stream *stream, const AudioRenderingPara
   }
 }
 
+void AudioRenderBackend::TruncateCache(const rational &r)
+{
+  int seq_length = params_.time_to_bytes(r);
+
+  QFile cache_pcm(CachePathName());
+
+  if (cache_pcm.size() > seq_length) {
+    cache_pcm.resize(seq_length);
+  }
+}
+
 bool AudioRenderBackend::ConformWaitInfo::operator==(const AudioRenderBackend::ConformWaitInfo &rhs) const
 {
   return rhs.params == params

app/render/backend/audiorenderbackend.h

@@ -74,6 +74,8 @@ private slots:
 
   void ConformUpdated(Stream *stream, const AudioRenderingParams& params);
 
+  void TruncateCache(const rational& r);
+
 };
 
 #endif // AUDIORENDERBACKEND_H