[HTML5] Refactor audio drivers. Implement AudioWorklet w/o threads.

Performances are not great in general, bad on Firefox, on Chrome, well,
it could be an improvement. Leave it as a fallback for now, but can be
forced via project settings if desired (or custom JavaScript logic via
the "args" option).

I'm actually surprised this works, it involves so many allocations, but
there's no way around it when SharedArrayBuffer is not available :(.

1 files changed, 96 insertions, 61 deletions

diff --git a/platform/javascript/audio_driver_javascript.h b/platform/javascript/audio_driver_javascript.h
index 393693640f..6a0b4bcb0e 100644
--- a/platform/javascript/audio_driver_javascript.h
+++ b/platform/javascript/audio_driver_javascript.h
@@ -38,52 +38,15 @@
 #include "godot_audio.h"
 
 class AudioDriverJavaScript : public AudioDriver {
-public:
-	class AudioNode {
-	public:
-		virtual int create(int p_buffer_size, int p_output_channels) = 0;
-		virtual void start(float *p_out_buf, int p_out_buf_size, float *p_in_buf, int p_in_buf_size) = 0;
-		virtual void finish() {}
-		virtual void lock() {}
-		virtual void unlock() {}
-		virtual ~AudioNode() {}
-	};
-
-	class WorkletNode : public AudioNode {
-	private:
-		enum {
-			STATE_LOCK,
-			STATE_PROCESS,
-			STATE_SAMPLES_IN,
-			STATE_SAMPLES_OUT,
-			STATE_MAX,
-		};
-		Mutex mutex;
-		Thread thread;
-		bool quit = false;
-		int32_t state[STATE_MAX] = { 0 };
-
-		static void _audio_thread_func(void *p_data);
-
-	public:
-		int create(int p_buffer_size, int p_output_channels) override;
-		void start(float *p_out_buf, int p_out_buf_size, float *p_in_buf, int p_in_buf_size) override;
-		void finish() override;
-		void lock() override;
-		void unlock() override;
-	};
-
-	class ScriptProcessorNode : public AudioNode {
-	private:
-		static void _process_callback();
-
-	public:
-		int create(int p_buffer_samples, int p_channels) override;
-		void start(float *p_out_buf, int p_out_buf_size, float *p_in_buf, int p_in_buf_size) override;
-	};
-
 private:
-	AudioNode *node = nullptr;
+	struct AudioContext {
+		bool inited = false;
+		float output_latency = 0.0;
+		int state = -1;
+		int channel_count = 0;
+		int mix_rate = 0;
+	};
+	static AudioContext audio_context;
 
 	float *output_rb = nullptr;
 	float *input_rb = nullptr;
@@ -91,36 +54,108 @@ private:
 	int buffer_length = 0;
 	int mix_rate = 0;
 	int channel_count = 0;
-	int state = 0;
-	float output_latency = 0.0;
 
 	static void _state_change_callback(int p_state);
 	static void _latency_update_callback(float p_latency);
 
+	static AudioDriverJavaScript *singleton;
+
 protected:
 	void _audio_driver_process(int p_from = 0, int p_samples = 0);
 	void _audio_driver_capture(int p_from = 0, int p_samples = 0);
+	float *get_output_rb() const { return output_rb; }
+	float *get_input_rb() const { return input_rb; }
+
+	virtual Error create(int &p_buffer_samples, int p_channels) = 0;
+	virtual void start(float *p_out_buf, int p_out_buf_size, float *p_in_buf, int p_in_buf_size) = 0;
+	virtual void finish_driver() {}
 
 public:
 	static bool is_available();
 
-	static AudioDriverJavaScript *singleton;
+	virtual Error init() final;
+	virtual void start() final;
+	virtual void finish() final;
+
+	virtual float get_latency() override;
+	virtual int get_mix_rate() const override;
+	virtual SpeakerMode get_speaker_mode() const override;
+
+	virtual Error capture_start() override;
+	virtual Error capture_stop() override;
+
+	static void resume();
+
+	AudioDriverJavaScript() {}
+};
+
+#ifdef NO_THREADS
+class AudioDriverScriptProcessor : public AudioDriverJavaScript {
+private:
+	static void _process_callback();
+
+	static AudioDriverScriptProcessor *singleton;
+
+protected:
+	Error create(int &p_buffer_samples, int p_channels) override;
+	void start(float *p_out_buf, int p_out_buf_size, float *p_in_buf, int p_in_buf_size) override;
+
+public:
+	virtual const char *get_name() const override { return "ScriptProcessor"; }
+
+	virtual void lock() override {}
+	virtual void unlock() override {}
+
+	AudioDriverScriptProcessor() { singleton = this; }
+};
+
+class AudioDriverWorklet : public AudioDriverJavaScript {
+private:
+	static void _process_callback(int p_pos, int p_samples);
+	static void _capture_callback(int p_pos, int p_samples);
+
+	static AudioDriverWorklet *singleton;
+
+protected:
+	virtual Error create(int &p_buffer_size, int p_output_channels) override;
+	virtual void start(float *p_out_buf, int p_out_buf_size, float *p_in_buf, int p_in_buf_size) override;
 
-	virtual const char *get_name() const;
+public:
+	virtual const char *get_name() const override { return "AudioWorklet"; }
+
+	virtual void lock() override {}
+	virtual void unlock() override {}
 
-	virtual Error init();
-	virtual void start();
-	void resume();
-	virtual float get_latency();
-	virtual int get_mix_rate() const;
-	virtual SpeakerMode get_speaker_mode() const;
-	virtual void lock();
-	virtual void unlock();
-	virtual void finish();
+	AudioDriverWorklet() { singleton = this; }
+};
+#else
+class AudioDriverWorklet : public AudioDriverJavaScript {
+private:
+	enum {
+		STATE_LOCK,
+		STATE_PROCESS,
+		STATE_SAMPLES_IN,
+		STATE_SAMPLES_OUT,
+		STATE_MAX,
+	};
+	Mutex mutex;
+	Thread thread;
+	bool quit = false;
+	int32_t state[STATE_MAX] = { 0 };
 
-	virtual Error capture_start();
-	virtual Error capture_stop();
+	static void _audio_thread_func(void *p_data);
 
-	AudioDriverJavaScript();
+protected:
+	virtual Error create(int &p_buffer_size, int p_output_channels) override;
+	virtual void start(float *p_out_buf, int p_out_buf_size, float *p_in_buf, int p_in_buf_size) override;
+	virtual void finish_driver() override;
+
+public:
+	virtual const char *get_name() const override { return "AudioWorklet"; }
+
+	void lock() override;
+	void unlock() override;
 };
 #endif
+
+#endif