Created a single source for querying the quantum size

A single JS function exists for the quantum size, the value is also passed to the processor node on creation.

Author: cwoffenden

src/audio_worklet.js

@@ -31,16 +31,15 @@ function createWasmAudioWorkletProcessor(audioParams) {
       let opts = args.processorOptions;
       this.callbackFunction = Module['wasmTable'].get(opts['cb']);
       this.userData = opts['ud'];
+      // Plus the number of samples to process, fixed for the lifetime of the context that created this processor
+      this.quantumSize = opts['qs'];
     }
 
     static get parameterDescriptors() {
       return audioParams;
     }
 
     process(inputList, outputList, parameters) {
-      // hardcoding this until the Web Audio 1.1 API spec makes it into browsers and we can get the AudioWorkletProcessor's context quantum
-      const quantumSize = 128;
-
       // Marshal all inputs and parameters to the Wasm memory on the thread stack,
       // then perform the wasm audio worklet call,
       // and finally marshal audio output data back.
@@ -54,7 +53,7 @@ function createWasmAudioWorkletProcessor(audioParams) {
         didProduceAudio, paramArray;
 
       // Calculate how much stack space is needed.
-      const quantumBytes = quantumSize * 4;
+      const quantumBytes = this.quantumSize * 4;
       for (i of inputList) stackMemoryNeeded += i.length * quantumBytes;
       for (i of outputList) stackMemoryNeeded += i.length * quantumBytes;
       for (i in parameters) stackMemoryNeeded += parameters[i].byteLength + {{{ C_STRUCTS.AudioParamFrame.__size__ }}}, ++numParams;
@@ -68,7 +67,7 @@ function createWasmAudioWorkletProcessor(audioParams) {
       for (i of inputList) {
         // Write the AudioSampleFrame struct instance
         HEAPU32[k + {{{ C_STRUCTS.AudioSampleFrame.numberOfChannels / 4 }}}] = i.length;
-        HEAPU32[k + {{{ C_STRUCTS.AudioSampleFrame.quantumSize / 4 }}}] = quantumSize;
+        HEAPU32[k + {{{ C_STRUCTS.AudioSampleFrame.quantumSize / 4 }}}] = this.quantumSize;
         HEAPU32[k + {{{ C_STRUCTS.AudioSampleFrame.data / 4 }}}] = dataPtr;
         k += {{{ C_STRUCTS.AudioSampleFrame.__size__ / 4 }}};
         // Marshal the input audio sample data for each audio channel of this input
@@ -85,7 +84,7 @@ function createWasmAudioWorkletProcessor(audioParams) {
       for (i of outputList) {
         // Write the AudioSampleFrame struct instance
         HEAPU32[k + {{{ C_STRUCTS.AudioSampleFrame.numberOfChannels / 4 }}}] = i.length;
-        HEAPU32[k + {{{ C_STRUCTS.AudioSampleFrame.quantumSize / 4 }}}] = quantumSize;
+        HEAPU32[k + {{{ C_STRUCTS.AudioSampleFrame.quantumSize / 4 }}}] = this.quantumSize;
         HEAPU32[k + {{{ C_STRUCTS.AudioSampleFrame.data / 4 }}}] = dataPtr;
         k += {{{ C_STRUCTS.AudioSampleFrame.__size__ / 4 }}};
         // Reserve space for the output data
@@ -114,7 +113,7 @@ function createWasmAudioWorkletProcessor(audioParams) {
         // not have one, so manually copy all bytes in)
         for (i of outputList) {
           for (j of i) {
-            for (k = 0; k < quantumSize; ++k) {
+            for (k = 0; k < this.quantumSize; ++k) {
               j[k] = HEAPF32[outputDataPtr++];
             }
           }

src/library_webaudio.js

@@ -37,11 +37,21 @@ let LibraryWebAudio = {
   // Wasm handle ID.
   $emscriptenGetAudioObject: (objectHandle) => EmAudio[objectHandle],
 
-  // emscripten_create_audio_context() does not itself use
+  // Performs the work of getting the AudioContext's quantum size.
+  $emscriptenGetContextQuantumSize: (contextHandle) => {
+    // TODO: in a future release this will be something like:
+    //   return EmAudio[contextHandle].renderQuantumSize || 128;
+    // It comes two caveats: it needs the hint when generating the context adding to
+    // emscripten_create_audio_context(), and altering the quantum requires a secure
+    // context and fallback implementing. Until then we simply use the 1.0 API value:
+    return 128;
+  },
+
+  // emscripten_create_audio_context() does not itself use the
   // emscriptenGetAudioObject() function, but mark it as a dependency, because
   // the user will not be able to utilize the node unless they call
   // emscriptenGetAudioObject() on it on JS side to connect it to the graph, so
-  // this avoids the user needing to manually do it on the command line.
+  // this avoids the user needing to manually add the dependency on the command line.
   emscripten_create_audio_context__deps: ['$emscriptenRegisterAudioObject', '$emscriptenGetAudioObject'],
   emscripten_create_audio_context: (options) => {
     let ctx = window.AudioContext || window.webkitAudioContext;
@@ -264,6 +274,7 @@ let LibraryWebAudio = {
     });
   },
 
+  emscripten_create_wasm_audio_worklet_node__deps: ['$emscriptenGetContextQuantumSize'],
   emscripten_create_wasm_audio_worklet_node: (contextHandle, name, options, callback, userData) => {
 #if ASSERTIONS
     assert(contextHandle, `Called emscripten_create_wasm_audio_worklet_node() with a null Web Audio Context handle!`);
@@ -282,7 +293,11 @@ let LibraryWebAudio = {
       numberOfInputs: HEAP32[options],
       numberOfOutputs: HEAP32[options+1],
       outputChannelCount: HEAPU32[options+2] ? readChannelCountArray(HEAPU32[options+2]>>2, HEAP32[options+1]) : void 0,
-      processorOptions: { 'cb': callback, 'ud': userData }
+      processorOptions: {
+        'cb': callback,
+        'ud': userData,
+        'qs': emscriptenGetContextQuantumSize(contextHandle)
+      }
     } : void 0;
 
 #if WEBAUDIO_DEBUG
@@ -293,14 +308,13 @@ let LibraryWebAudio = {
   },
 #endif // ~AUDIO_WORKLET
 
+  emscripten_audio_context_quantum_size__deps: ['$emscriptenGetContextQuantumSize'],
   emscripten_audio_context_quantum_size: (contextHandle) => {
 #if ASSERTIONS
     assert(EmAudio[contextHandle], `Called emscripten_audio_context_quantum_size() with an invalid Web Audio Context handle ${contextHandle}`);
     assert(EmAudio[contextHandle] instanceof (window.AudioContext || window.webkitAudioContext), `Called emscripten_audio_context_quantum_size() on handle ${contextHandle} that is not an AudioContext, but of type ${EmAudio[contextHandle]}`);
 #endif
-    // TODO: once the Web Audio 1.1 API is implemented we can query the context for its renderQuantumSize
-    // (With two caveats: it needs the hint when generating the context adding, plus it requires a secure context and fallback implementing)
-    return 128;
+    return emscriptenGetContextQuantumSize(contextHandle);
   },
 
   emscripten_audio_node_connect: (source, destination, outputIndex, inputIndex) => {