audio_core: Implement OpenAL backend (#6450)

src/audio_core/openal_input.h

@@ -0,0 +1,35 @@
+// Copyright 2023 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <memory>
+#include <string>
+#include <vector>
+#include "audio_core/input.h"
+
+namespace AudioCore {
+
+class OpenALInput final : public Input {
+public:
+    explicit OpenALInput(std::string device_id);
+    ~OpenALInput() override;
+
+    void StartSampling(const InputParameters& params) override;
+
+    void StopSampling() override;
+
+    void AdjustSampleRate(u32 sample_rate) override;
+
+    Samples Read() override;
+
+private:
+    struct Impl;
+    std::unique_ptr<Impl> impl;
+    std::string device_id;
+};
+
+std::vector<std::string> ListOpenALInputDevices();
+
+} // namespace AudioCore