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Allow the number of channels to increase (or the audio chain to change)
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Typed views are recreated if needed but otherwise are reused.
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cwoffenden committed Oct 18, 2024
1 parent 9b3dbb6 commit d4680ca
Showing 1 changed file with 16 additions and 12 deletions.
28 changes: 16 additions & 12 deletions src/audio_worklet.js
Original file line number Diff line number Diff line change
Expand Up @@ -38,8 +38,8 @@ function createWasmAudioWorkletProcessor(audioParams) {
// shouldn't be required (to be verified).
this.samplesPerChannel = opts['sc'];
// Typed views of the output buffers on the worklet's stack, which after
// creation should not change (since the stack is passed externally once).
this.outputViews = null;
// creation should only change if the audio chain changes.
this.outputViews = [];
}

static get parameterDescriptors() {
Expand All @@ -57,7 +57,7 @@ function createWasmAudioWorkletProcessor(audioParams) {
bytesPerChannel = this.samplesPerChannel * 4,
stackMemoryNeeded = (numInputs + numOutputs) * {{{ C_STRUCTS.AudioSampleFrame.__size__ }}},
oldStackPtr = stackSave(),
inputsPtr, outputsPtr, outputDataPtr, paramsPtr,
inputsPtr, outputsPtr, outputDataPtr, paramsPtr, requiredViews = 0,
didProduceAudio, paramArray;

// Calculate how much stack space is needed.
Expand Down Expand Up @@ -96,18 +96,22 @@ function createWasmAudioWorkletProcessor(audioParams) {
k += {{{ C_STRUCTS.AudioSampleFrame.__size__ / 4 }}};
// Reserve space for the output data
dataPtr += bytesPerChannel * i.length;
// How many output views are needed in total?
requiredViews += i.length;
}
if (!this.outputViews) {

// Verify we have enough views (it doesn't matter if we have too many, any
// excess won't be accessed) then also verify the views' start address
// hasn't changed.
// TODO: allocate space for outputDataPtr before any inputs?
k = outputDataPtr;
if (this.outputViews.length < requiredViews || (this.outputViews.length && this.outputViews[0].byteOffset != k << 2)) {
this.outputViews = [];
k = outputDataPtr;
for (/*which output*/ i of outputList) {
for (/*which channel*/ j of i) {
this.outputViews.push({
// dataPtr is the sanity check (to be implemented)
// dataSub is the one-time subarray into the heap
dataPtr: k,
dataSub: HEAPF32.subarray(k, k += this.samplesPerChannel)
});
this.outputViews.push(
HEAPF32.subarray(k, k += this.samplesPerChannel)
);
}
}
}
Expand All @@ -134,7 +138,7 @@ function createWasmAudioWorkletProcessor(audioParams) {
k = 0;
for (i of outputList) {
for (j of i) {
j.set(this.outputViews[k++].dataSub);
j.set(this.outputViews[k++]);
}
}
}
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