renderer: use a dedicated decoder per thread

app/render/backend/renderworker.cpp

@@ -26,10 +26,9 @@
 
 OLIVE_NAMESPACE_ENTER
 
-RenderWorker::RenderWorker(DecoderCache *decoder_cache, QObject *parent) :
+RenderWorker::RenderWorker(QObject *parent) :
   QObject(parent),
-  started_(false),
-  decoder_cache_(decoder_cache)
+  started_(false)
 {
 }
 
@@ -50,6 +49,8 @@ void RenderWorker::Close()
 {
   CloseInternal();
 
+  decoder_cache_.Clear();
+
   started_ = false;
 }
 
@@ -82,11 +83,9 @@ StreamPtr RenderWorker::ResolveStreamFromInput(NodeInput *input)
 
 DecoderPtr RenderWorker::ResolveDecoderFromInput(StreamPtr stream)
 {
-  QMutexLocker locker(decoder_cache_->lock());
-
   // Access a map of Node inputs and decoder instances and retrieve a frame!
 
-  DecoderPtr decoder = decoder_cache_->Get(stream.get());
+  DecoderPtr decoder = decoder_cache_.Get(stream.get());
 
   if (!decoder && stream) {
     // Create a new Decoder here
@@ -94,7 +93,7 @@ DecoderPtr RenderWorker::ResolveDecoderFromInput(StreamPtr stream)
     decoder->set_stream(stream);
 
     if (decoder->Open()) {
-      decoder_cache_->Add(stream.get(), decoder);
+      decoder_cache_.Add(stream.get(), decoder);
     } else {
       decoder = nullptr;
       qWarning() << "Failed to open decoder for" << stream->footage()->filename() << "::" << stream->index();