[HTML5] AudioWorklet API implementation.

Rewrote AudioDriverJavaScript to support multiple processor nodes.
The old (and deprecated) ScriptProcessorNode when threads are not
available, and the new AudioWorklet API when threads are enabled.

The new implementation uses two ring buffers and a shared state to
communicated with the AudioWorklet thread.

The audio.worklet.js JavaScript file is always added to the export
template, but only really used (and downloaded) in the thread build.

1 files changed, 69 insertions, 27 deletions

diff --git a/platform/javascript/audio_driver_javascript.h b/platform/javascript/audio_driver_javascript.h
index 60ad6480c9..f112a1ede4 100644
--- a/platform/javascript/audio_driver_javascript.h
+++ b/platform/javascript/audio_driver_javascript.h
@@ -31,54 +31,96 @@
 #ifndef AUDIO_DRIVER_JAVASCRIPT_H
 #define AUDIO_DRIVER_JAVASCRIPT_H
 
-#include "servers/audio_server.h"
-
 #include "core/os/mutex.h"
 #include "core/os/thread.h"
+#include "servers/audio_server.h"
+
+#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 = nullptr;
+		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:
-	float *internal_buffer = nullptr;
+	AudioNode *node = nullptr;
+
+	float *output_rb = nullptr;
+	float *input_rb = nullptr;
 
 	int buffer_length = 0;
 	int mix_rate = 0;
 	int channel_count = 0;
+	int state = 0;
+	float output_latency = 0.0;
 
-#ifndef NO_THREADS
-	Mutex mutex;
-	Thread *thread = nullptr;
-	bool quit = false;
-	bool needs_process = true;
+	static void _state_change_callback(int p_state);
+	static void _latency_update_callback(float p_latency);
 
-	static void _audio_thread_func(void *p_data);
-#endif
-	static void _audio_driver_process_start();
-	static void _audio_driver_process_end();
-	static void _audio_driver_process_capture(float p_sample);
-	void _audio_driver_process();
+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);
 
 public:
 	static bool is_available();
-	void process_capture(float sample);
 
 	static AudioDriverJavaScript *singleton;
 
-	const char *get_name() const override;
+	virtual const char *get_name() const;
 
-	Error init() override;
-	void start() override;
+	virtual Error init();
+	virtual void start();
 	void resume();
-	float get_latency() override;
-	int get_mix_rate() const override;
-	SpeakerMode get_speaker_mode() const override;
-	void lock() override;
-	void unlock() override;
-	void finish() override;
+	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();
 
-	Error capture_start() override;
-	Error capture_stop() override;
+	virtual Error capture_start();
+	virtual Error capture_stop();
 
 	AudioDriverJavaScript();
 };
-
 #endif