Initial mixer

Rough implementation to see what needs doing in JS vs Wasm.

Author: cwoffenden

test/test_interactive.py

@@ -306,6 +306,12 @@ def test_audio_worklet_tone_generator(self):
   def test_audio_worklet_modularize(self):
     self.btest('webaudio/audioworklet.c', expected='0', args=['-sAUDIO_WORKLET', '-sWASM_WORKERS', '-sMINIMAL_RUNTIME', '-sMODULARIZE'])
 
+  # Tests an AudioWorklet with multiple stereo inputs mixing to a single output
+  def test_audio_worklet_stereo_io(self):
+    os.mkdir('audio_files')
+    shutil.copy(test_file('webaudio/audio_files/emscripten-beat.mp3'), 'audio_files/')
+    shutil.copy(test_file('webaudio/audio_files/emscripten-bass.mp3'), 'audio_files/')
+    self.btest('webaudio/audioworklet_in_out_stereo.c', expected='0', args=['-sAUDIO_WORKLET', '-sWASM_WORKERS'])
 
 class interactive64(interactive):
   def setUp(self):

test/webaudio/audioworklet_in_out_stereo.c

@@ -1,35 +1,97 @@
+#include <stdio.h>
+
 #include <emscripten/em_js.h>
 #include <emscripten/webaudio.h>
 
-#define AUDIO_STACK_SIZE 2048
+#define AUDIO_STACK_SIZE 4096
+
+#ifdef REPORT_RESULT
+void playedAndMixed(void* data) {
+	REPORT_RESULT(0);
+}
+#endif
 
-EM_JS(bool, addAudio, (EMSCRIPTEN_WEBAUDIO_T ctxHnd, const char* url, const char* label), {
+// Adds a button to play and stop an audio file
+EM_JS(bool, addAudio, (EMSCRIPTEN_WEBAUDIO_T ctxHnd, EMSCRIPTEN_AUDIO_WORKLET_NODE_T nodeHnd, int index, const char* url, const char* label), {
 	var context = emscriptenGetAudioObject(ctxHnd);
 	if (context) {
 		var audio = document.createElement('audio');
 		audio.src = UTF8ToString(url);
 		audio.loop = true;
 		var track = context.createMediaElementSource(audio);
-		track.connect(context.destination);
-		
+
+		var worklet = emscriptenGetAudioObject(nodeHnd);
+		track.connect(worklet ? worklet : context.destination, 0, index);
+
 		var button = document.createElement('button');
 		button.innerHTML = UTF8ToString(label);
 		button.onclick = () => {
 			if (context.state == 'suspended') {
 				context.resume();
 			}
-			audio.play();
+			if (audio.paused) {
+				audio.currentTime = 0;
+				audio.play();
+			} else {
+				audio.pause();
+			}
+			
 		};
-		
 		document.body.appendChild(button);
 		return true;
 	}
 	return false;
 });
 
+bool process(int numInputs, const AudioSampleFrame* inputs, int numOutputs, AudioSampleFrame* outputs, int numParams, const AudioParamFrame* params, void* data) {
+	for (int o = 0; o < numOutputs; o++) {
+		for (int n = outputs[o].samplesPerChannel * outputs[o].numberOfChannels - 1; n >= 0; n--) {
+			outputs[o].data[n] = 0.0f;
+			for (int i = 0; i < numInputs; i++) {
+				outputs[o].data[n] += inputs[i].data[n] * 0.75f;
+			}
+		}
+	}
+	return true;
+}
+
+void processorCreated(EMSCRIPTEN_WEBAUDIO_T context, bool success, void* data) {
+	if (success) {
+		printf("Audio worklet processor created\n");
+
+		int outputChannelCounts[1] = { 2 };
+		EmscriptenAudioWorkletNodeCreateOptions opts = {
+			.numberOfInputs  = 2,
+			.numberOfOutputs = 1,
+			.outputChannelCounts = outputChannelCounts
+		};
+		EMSCRIPTEN_AUDIO_WORKLET_NODE_T worklet = emscripten_create_wasm_audio_worklet_node(context, "mixer", &opts, &process, NULL);
+		emscripten_audio_node_connect(worklet, context, 0, 0);
+
+		addAudio(context, worklet, 0, "audio_files/emscripten-beat.mp3", "Toggle Beat");
+		addAudio(context, worklet, 1, "audio_files/emscripten-bass.mp3", "Toggle Bass");
+	} else {
+		printf("Audio worklet node creation failed\n");
+	}
+}
+
+void initialised(EMSCRIPTEN_WEBAUDIO_T context, bool success, void* data) {
+	if (success) {
+		printf("Audio worklet initialised\n");
+
+		WebAudioWorkletProcessorCreateOptions opts = {
+			.name = "mixer",
+		};
+		emscripten_create_wasm_audio_worklet_processor_async(context, &opts, &processorCreated, NULL);
+	} else {
+		printf("Audio worklet failed to initialise\n");
+	}
+}
+
 int main() {
+	static char workletStack[AUDIO_STACK_SIZE];
 	EMSCRIPTEN_WEBAUDIO_T context = emscripten_create_audio_context(NULL);
+	emscripten_start_wasm_audio_worklet_thread_async(context, workletStack, sizeof(workletStack), initialised, NULL);
 
-	addAudio(context, "audio_files/emscripten-beat.mp3", "Play Beat");
-	addAudio(context, "audio_files/emscripten-bass.mp3", "Play Bass");
+	return 0;
 }