@audio/gain

Audio gain DSP module

Amplify input values.

Usage

./gain.js

import gain from '@audio/gain';

// mono, k-param gain
[output] = gain([[0.1,0.2,...inputValues]], .75);

// stereo, a-param gain
[outputLeft, outputRight] = gain([[0.1,...leftInput], [-0.1,...rightInput]], [.5,.6,...gainValues]);

// multichannel, a-param gain
outputChannels = gain([...inputChannels], gainValues);

./gain.wasm

Raw WASM function requires a bit of memory management.

const memory = new WebAssembly.Memory({initial:1, maximum: 8}) // can be shared

WebAssembly.instantiateStreaming(fetch('./gain.wasm'), { init: { memory } })
.then(({ instance }) => {
	const { gain, block, blockSize } = instance.exports

	const data = new Float64Array(memory.buffer) // memory view
	const inPtr = block(2), gainPtr = block(1) // allocate batch slots for audio buffers

	// sample processing loop
	const processGain = (input, output, param) => {
		// adjust processing block size
		blockSize.value = input[0].length, outPtr

		// write input to memory
		data.set(input[0], inPtr), data.set(input[1], inPtr+blockSize)

		// process a-rate (accurate) gain values
		if (param.gain.length > 1) {
			data.set(param.gain, gainPtr)
			outPtr = gain(inPtr, gainPtr)
		}
		// process k-rate (controlling) gain values
		else {
			outPtr = gain(inPtr, param.gain[0])
		}

		// write output from memory
		output[0].set(data.subarray(outPtr, blockSize))
		output[1].set(data.subarray(outPtr+blockSize, blockSize))
	}
});

This is illustrative flow, can be enhanced to use multiple channels, shared memory etc.

./gain.son

Can be used in sonr as:

# './gain.son': gain;

gain(mySource, 0.45);	// direct fn
mySource | gain(0.45); // pipe style

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