1 files changed, 48 insertions, 23 deletions

diff --git a/platform/javascript/audio_driver_javascript.cpp b/platform/javascript/audio_driver_javascript.cpp
index 03ca5f78d1..9604914b2c 100644
--- a/platform/javascript/audio_driver_javascript.cpp
+++ b/platform/javascript/audio_driver_javascript.cpp
@@ -30,10 +30,21 @@
 
 #include "audio_driver_javascript.h"
 
+#include "core/project_settings.h"
+
 #include <emscripten.h>
 
 AudioDriverJavaScript *AudioDriverJavaScript::singleton = nullptr;
 
+bool AudioDriverJavaScript::is_available() {
+	return EM_ASM_INT({
+		if (!(window.AudioContext || window.webkitAudioContext)) {
+			return 0;
+		}
+		return 1;
+	}) != 0;
+}
+
 const char *AudioDriverJavaScript::get_name() const {
 	return "JavaScript";
 }
@@ -62,38 +73,36 @@ void AudioDriverJavaScript::process_capture(float sample) {
 }
 
 Error AudioDriverJavaScript::init() {
+	int mix_rate = GLOBAL_GET("audio/mix_rate");
+	int latency = GLOBAL_GET("audio/output_latency");
+
 	/* clang-format off */
 	_driver_id = EM_ASM_INT({
+		const MIX_RATE = $0;
+		const LATENCY = $1 / 1000;
 		return Module.IDHandler.add({
-			'context': new (window.AudioContext || window.webkitAudioContext),
+			'context': new (window.AudioContext || window.webkitAudioContext)({ sampleRate: MIX_RATE, latencyHint: LATENCY}),
 			'input': null,
 			'stream': null,
 			'script': null
 		});
-	});
+	}, mix_rate, latency);
 	/* clang-format on */
 
 	int channel_count = get_total_channels_by_speaker_mode(get_speaker_mode());
+	buffer_length = closest_power_of_2((latency * mix_rate / 1000) * channel_count);
 	/* clang-format off */
 	buffer_length = EM_ASM_INT({
 		var ref = Module.IDHandler.get($0);
-		var ctx = ref['context'];
-		var CHANNEL_COUNT = $1;
-
-		var channelCount = ctx.destination.channelCount;
-		var script = null;
-		try {
-			// Try letting the browser recommend a buffer length.
-			script = ctx.createScriptProcessor(0, 2, channelCount);
-		} catch (e) {
-			// ...otherwise, default to 4096.
-			script = ctx.createScriptProcessor(4096, 2, channelCount);
-		}
+		const ctx = ref['context'];
+		const BUFFER_LENGTH = $1;
+		const CHANNEL_COUNT = $2;
+
+		var script = ctx.createScriptProcessor(BUFFER_LENGTH, 2, CHANNEL_COUNT);
 		script.connect(ctx.destination);
 		ref['script'] = script;
-
 		return script.bufferSize;
-	}, _driver_id, channel_count);
+	}, _driver_id, buffer_length, channel_count);
 	/* clang-format on */
 	if (!buffer_length) {
 		return FAILED;
@@ -156,6 +165,25 @@ void AudioDriverJavaScript::resume() {
 	/* clang-format on */
 }
 
+float AudioDriverJavaScript::get_latency() {
+	/* clang-format off */
+	return EM_ASM_DOUBLE({
+		const ref = Module.IDHandler.get($0);
+		var latency = 0;
+		if (ref && ref['context']) {
+			const ctx = ref['context'];
+			if (ctx.baseLatency) {
+				latency += ctx.baseLatency;
+			}
+			if (ctx.outputLatency) {
+				latency += ctx.outputLatency;
+			}
+		}
+		return latency;
+	}, _driver_id);
+	/* clang-format on */
+}
+
 int AudioDriverJavaScript::get_mix_rate() const {
 	/* clang-format off */
 	return EM_ASM_INT({
@@ -188,12 +216,14 @@ void AudioDriverJavaScript::finish_async() {
 
 	/* clang-format off */
 	EM_ASM({
-		var ref = Module.IDHandler.get($0);
+		const id = $0;
+		var ref = Module.IDHandler.get(id);
 		Module.async_finish.push(new Promise(function(accept, reject) {
 			if (!ref) {
-				console.log("Ref not found!", $0, Module.IDHandler);
+				console.log("Ref not found!", id, Module.IDHandler);
 				setTimeout(accept, 0);
 			} else {
+				Module.IDHandler.remove(id);
 				const context = ref['context'];
 				// Disconnect script and input.
 				ref['script'].disconnect();
@@ -207,7 +237,6 @@ void AudioDriverJavaScript::finish_async() {
 				});
 			}
 		}));
-		Module.IDHandler.remove($0);
 	}, id);
 	/* clang-format on */
 }
@@ -274,9 +303,5 @@ Error AudioDriverJavaScript::capture_stop() {
 }
 
 AudioDriverJavaScript::AudioDriverJavaScript() {
-	_driver_id = 0;
-	internal_buffer = nullptr;
-	buffer_length = 0;
-
 	singleton = this;
 }