stash: web audio api

Author: Desdaemon

CMakeLists.txt

@@ -885,6 +885,7 @@ endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Emscripten")
 	option(PLAYER_JS_BUILD_SHELL
 		"Build the Player executable as a shell file (.html) instead of a standalone javascript file (.js)" OFF)
+	option(PLAYER_JS_AUDIO_WORKLETS "Use the newer Web Audio API instead of the built-in support from SDL2" OFF)
 	set(PLAYER_JS_GAME_URL "games/" CACHE STRING "Game URL/directory where the web player searches for games")
 	set(PLAYER_JS_OUTPUT_NAME "easyrpg-player" CACHE STRING "Output name of the js, html and wasm files")
 	set_property(SOURCE src/async_handler.cpp APPEND PROPERTY
@@ -1260,6 +1261,9 @@ if(PLAYER_BUILD_EXECUTABLE AND ${PLAYER_TARGET_PLATFORM} MATCHES "^SDL.*$" AND N
 		# Do not confuse this with our own -DUSE_SDL
 		# Prevent Emscripten from pulling in bundled SDL headers that break the build
 		target_compile_options(${PROJECT_NAME} PUBLIC "-sUSE_SDL=0")
+		if(PLAYER_JS_AUDIO_WORKLETS)
+			target_compile_options(${PROJECT_NAME} PUBLIC "-pthread")
+		endif()
 
 		set(PLAYER_JS_PREJS "${CMAKE_CURRENT_SOURCE_DIR}/resources/emscripten/emscripten-pre.js")
 		set(PLAYER_JS_POSTJS "${CMAKE_CURRENT_SOURCE_DIR}/resources/emscripten/emscripten-post.js")
@@ -1279,15 +1283,26 @@ if(PLAYER_BUILD_EXECUTABLE AND ${PLAYER_TARGET_PLATFORM} MATCHES "^SDL.*$" AND N
 			set_property(TARGET ${EXE_NAME} APPEND_STRING PROPERTY LINK_FLAGS " --shell-file ${PLAYER_JS_SHELL}")
 		endif()
 
+		if(PLAYER_JS_AUDIO_WORKLETS)
+			set_property(TARGET ${EXE_NAME} APPEND_STRING PROPERTY LINK_FLAGS
+				" -sINITIAL_MEMORY=67108864 -sAUDIO_WORKLET -sWASM_WORKERS -sUSE_PTHREADS -sPTHREAD_POOL_SIZE=1 -sPTHREAD_POOL_SIZE_STRICT=2")
+		endif()
+
 		target_compile_options(${PROJECT_NAME} PUBLIC -fno-exceptions)
 
 		target_sources(${PROJECT_NAME} PRIVATE
 				src/platform/emscripten/clock.h
 				src/platform/emscripten/interface.cpp
 				src/platform/emscripten/interface.h)
+		if(PLAYER_JS_AUDIO_WORKLETS)
+			target_sources(${PROJECT_NAME} PRIVATE
+				src/platform/emscripten/audio.h
+				src/platform/emscripten/audio.cpp)
+		endif()
 
 		target_link_libraries(${EXE_NAME} "idbfs.js")
 		target_link_libraries(${EXE_NAME} "websocket.js")
+		target_link_libraries(${EXE_NAME} "wasmfs_fetch.js")
 		set_property(TARGET ${EXE_NAME} APPEND_STRING PROPERTY LINK_FLAGS " -s EXPORTED_RUNTIME_METHODS='[\"ccall\",\"cwrap\",\"intArrayFromString\",\"ALLOC_NORMAL\",\"allocate\",\"getValue\",\"FS\"]'")
 		set_target_properties(${EXE_NAME} PROPERTIES OUTPUT_NAME "${PLAYER_JS_OUTPUT_NAME}")
 	endif()

resources/emscripten/emscripten-pre.js

@@ -1,3 +1,5 @@
+const isMainThread = !!globalThis?.window;
+
 // Note: The `Module` context is already initialized as an
 // empty object by emscripten even before the pre script
 Object.assign(Module, {
@@ -13,6 +15,7 @@ Object.assign(Module, {
   },
 
   canvas: (() => {
+    if (!isMainThread) return undefined;
     const canvas = document.getElementById('canvas');
 
     // See http://www.khronos.org/registry/webgl/specs/latest/1.0/#5.15.2
@@ -28,6 +31,7 @@ Object.assign(Module, {
   })(),
 
   setStatus: text => {
+    if (!isMainThread) return;
     if (!Module.setStatus.last) Module.setStatus.last = {
       time: Date.now(),
       text: ''
@@ -54,7 +58,8 @@ var lang_pushed = false;
  * Parses the current location query to setup a specific game
  */
 function parseArgs () {
-  const items = window.location.search.substr(1).split("&");
+  if (!isMainThread) return [];
+  const items = location.search.substr(1).split("&");
   let result = [];
 
   // Store saves in subdirectory `Save`
@@ -139,7 +144,7 @@ if (Module.wsUrl === undefined) {
 }
 
 // Catch all errors occuring inside the window
-window.addEventListener('error', (event) => {
+globalThis.window?.addEventListener('error', (event) => {
   // workaround chrome bug: See https://github.com/EasyRPG/Player/issues/2806
   if (event.error.message.includes("side-effect in debug-evaluate") && event.defaultPrevented) {
     return;

src/audio_generic.cpp

@@ -301,11 +301,62 @@ bool GenericAudio::PlayOnChannel(SeChannel& chan, std::unique_ptr<AudioSeCache>
 	chan.paused = false; // Unpause channel -> Play it.
 	return true;
 }
-
 void GenericAudio::Decode(uint8_t* output_buffer, int buffer_length) {
+	auto [channel_active, total_volume, samples_per_frame] = GenericAudio::Decode(buffer_length);
+	if (channel_active) {
+		if (total_volume > 1.0) {
+			float threshold = 0.8;
+			for (unsigned i = 0; i < (unsigned)(samples_per_frame * 2); i++) {
+				float sample = mixer_buffer[i];
+				float sign = (sample < 0) ? -1.0 : 1.0;
+				sample /= sign;
+				//dynamic range compression
+				if (sample > threshold) {
+					sample_buffer[i] = sign * 32768.0 * (threshold + (1.0 - threshold) * (sample - threshold) / (total_volume - threshold));
+				} else {
+					sample_buffer[i] = sign * sample * 32768.0;
+				}
+			}
+		} else {
+			//No dynamic range compression necessary
+			for (unsigned i = 0; i < (unsigned)(samples_per_frame * 2); i++) {
+				sample_buffer[i] = mixer_buffer[i] * 32768.0;
+			}
+		}
+
+		memcpy(output_buffer, sample_buffer.data(), buffer_length);
+	} else {
+		memset(output_buffer, '\0', buffer_length);
+	}
+}
+
+void GenericAudio::Decode(float* output_buffer, int buffer_length) {
+	auto [channel_active, total_volume, samples_per_frame] = GenericAudio::Decode(buffer_length);
+	if (channel_active) {
+		if (total_volume > 1.0) {
+			float threshold = 0.8;
+			for (unsigned i = 0; i < (unsigned)(samples_per_frame * 2); ++i) {
+				float sample = mixer_buffer[i];
+				float sign = (sample < 0) ? -1.0 : 1.0;
+				sample /= sign;
+				if (sample > threshold) {
+					output_buffer[i] = sign * (threshold + (1.0 - threshold) * (sample - threshold) / (total_volume - threshold));
+				} else {
+					output_buffer[i] = sign * sample;
+				}
+			}
+		} else {
+			memcpy(output_buffer, mixer_buffer.data(), buffer_length);
+		}
+	} else {
+		memset(output_buffer, '\0', buffer_length);
+	}
+}
+
+GenericAudio::DecodeResult GenericAudio::Decode(int buffer_length) {
 	bool channel_active = false;
 	float total_volume = 0;
-	int samples_per_frame = buffer_length / output_format.channels / 2;
+	int samples_per_frame = buffer_length / output_format.channels / AudioDecoder::GetSamplesizeForFormat(output_format.format);
 
 	assert(buffer_length > 0);
 
@@ -471,32 +522,7 @@ void GenericAudio::Decode(uint8_t* output_buffer, int buffer_length) {
 			channel_active = true;
 		}
 	}
-
-	if (channel_active) {
-		if (total_volume > 1.0) {
-			float threshold = 0.8f;
-			for (unsigned i = 0; i < (unsigned)(samples_per_frame * 2); i++) {
-				float sample = mixer_buffer[i];
-				float sign = (sample < 0) ? -1.0 : 1.0;
-				sample /= sign;
-				//dynamic range compression
-				if (sample > threshold) {
-					sample_buffer[i] = sign * 32768.0 * (threshold + (1.0 - threshold) * (sample - threshold) / (total_volume - threshold));
-				} else {
-					sample_buffer[i] = sign * sample * 32768.0;
-				}
-			}
-		} else {
-			//No dynamic range compression necessary
-			for (unsigned i = 0; i < (unsigned)(samples_per_frame * 2); i++) {
-				sample_buffer[i] = mixer_buffer[i] * 32768.0;
-			}
-		}
-
-		memcpy(output_buffer, sample_buffer.data(), buffer_length);
-	} else {
-		memset(output_buffer, '\0', buffer_length);
-	}
+	return {channel_active, total_volume, samples_per_frame};
 }
 
 void GenericAudio::BgmChannel::Stop() {
@@ -505,9 +531,9 @@ void GenericAudio::BgmChannel::Stop() {
 		midi_out_used = false;
 		instance->midi_thread->GetMidiOut().Reset();
 		instance->midi_thread->GetMidiOut().Pause();
-	} else if (decoder) {
-		decoder.reset();
 	}
+	// Don't reset the decoder here, another thread could be using it right now
+	// it will be reset on the next call to Decode
 }
 
 void GenericAudio::BgmChannel::SetPaused(bool newPaused) {

src/audio_generic.h

@@ -70,6 +70,7 @@ class GenericAudio : public AudioInterface {
 	virtual void UnlockMutex() const = 0;
 
 	void Decode(uint8_t* output_buffer, int buffer_length);
+	void Decode(float* output_buffer, int buffer_length);
 
 private:
 	struct BgmChannel {
@@ -118,6 +119,12 @@ class GenericAudio : public AudioInterface {
 	std::vector<float> mixer_buffer = {};
 
 	std::unique_ptr<GenericAudioMidiOut> midi_thread;
+	typedef struct DecodeResult {
+		bool channel_active;
+		float total_volume;
+		int samples_per_frame;
+	} DecodeResult;
+	DecodeResult Decode(int buffer_length);
 };
 
 #endif