audio_core: Implement OpenAL backend (#6450)

src/audio_core/null_input.h

@@ -0,0 +1,35 @@
+// Copyright 2019 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <memory>
+#include <vector>
+#include "audio_core/input.h"
+#include "common/swap.h"
+#include "common/threadsafe_queue.h"
+
+namespace AudioCore {
+
+class NullInput final : public Input {
+public:
+    void StartSampling(const InputParameters& params) override {
+        parameters = params;
+        is_sampling = true;
+    }
+
+    void StopSampling() override {
+        is_sampling = false;
+    }
+
+    void AdjustSampleRate(u32 sample_rate) override {
+        parameters.sample_rate = sample_rate;
+    }
+
+    Samples Read() override {
+        return {};
+    }
+};
+
+} // namespace AudioCore