AUDIO: Add a NullAudioStream for streams that are dead-on-arrival

audio/audiostream.cpp

@@ -33,6 +33,7 @@
 #include "audio/decoders/quicktime.h"
 #include "audio/decoders/raw.h"
 #include "audio/decoders/vorbis.h"
+#include "audio/mixer.h"
 
 
 namespace Audio {
@@ -465,4 +466,24 @@ AudioStream *makeLimitingAudioStream(AudioStream *parentStream, const Timestamp
 	return new LimitingAudioStream(parentStream, length, disposeAfterUse);
 }
 
+/**
+ * An AudioStream that plays nothing and immediately returns that
+ * the endOfStream() has been reached
+ */
+class NullAudioStream : public AudioStream {
+public:
+        bool isStereo() const { return false; }
+        int getRate() const;
+        int readBuffer(int16 *data, const int numSamples) { return 0; }
+        bool endOfData() const { return true; }
+};
+
+int NullAudioStream::getRate() const {
+	return g_system->getMixer()->getOutputRate();
+}
+
+AudioStream *makeNullAudioStream() {
+	return new NullAudioStream();
+}
+
 } // End of namespace Audio

audio/audiostream.h

@@ -433,6 +433,12 @@ private:
 	Common::ScopedPtr<QueuingAudioStream> _stream;
 };
 
+/**
+ * Create an AudioStream that plays nothing and immediately returns that
+ * endOfStream() has been reached.
+ */
+AudioStream *makeNullAudioStream();
+
 } // End of namespace Audio
 
 #endif