Codex
97 lines
3.8 KiB
JavaScript
97 lines
3.8 KiB
JavaScript
import { fftInPlace } from "./fft.js";
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function throwIfAborted(signal) {
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if (signal?.aborted) {
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const error = new Error("STFT 계산이 취소되었습니다.");
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error.name = "AbortError";
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throw error;
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}
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}
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function yieldToEventLoop() {
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return new Promise((resolve) => setTimeout(resolve, 0));
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}
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export function hannWindow(size) {
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if (!Number.isInteger(size) || size < 2) throw new Error("Hann window 크기는 2 이상이어야 합니다.");
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const window = new Float64Array(size);
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for (let index = 0; index < size; index += 1) {
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window[index] = 0.5 - 0.5 * Math.cos((2 * Math.PI * index) / (size - 1));
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}
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return window;
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}
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export function getFrameCount(sampleCount, fftSize, hopSize) {
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if (!Number.isInteger(hopSize) || hopSize < 1 || hopSize > fftSize) {
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throw new Error("hopSize는 1 이상 fftSize 이하여야 합니다.");
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}
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return Math.max(1, 1 + Math.ceil(Math.max(0, sampleCount - fftSize) / hopSize));
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}
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export async function extractStftBins(channels, options) {
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const { fftSize, hopSize, bins, signal, onProgress, transformBatchSize = 32 } = options;
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if (!Array.isArray(channels) || channels.length === 0) throw new Error("마이크 채널이 필요합니다.");
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const sampleCount = channels[0].length;
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if (channels.some((channel) => channel.length !== sampleCount)) throw new Error("마이크 채널 길이가 다릅니다.");
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const uniqueBins = [...new Set(bins)].sort((a, b) => a - b);
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for (const bin of uniqueBins) {
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if (!Number.isInteger(bin) || bin < 0 || bin > fftSize / 2) throw new Error(`유효하지 않은 FFT bin: ${bin}`);
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}
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const frameCount = getFrameCount(sampleCount, fftSize, hopSize);
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const microphoneCount = channels.length;
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if (!Number.isInteger(transformBatchSize) || transformBatchSize < 1) {
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throw new Error("transformBatchSize는 1 이상의 정수여야 합니다.");
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}
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const spectra = new Map();
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for (const bin of uniqueBins) {
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spectra.set(bin, {
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real: new Float32Array(frameCount * microphoneCount),
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imaginary: new Float32Array(frameCount * microphoneCount),
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});
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}
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const window = hannWindow(fftSize);
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const real = new Float64Array(fftSize);
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const imaginary = new Float64Array(fftSize);
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const totalTransforms = frameCount * microphoneCount;
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let completedTransforms = 0;
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for (let frameIndex = 0; frameIndex < frameCount; frameIndex += 1) {
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const frameStart = frameIndex * hopSize;
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for (let microphoneIndex = 0; microphoneIndex < microphoneCount; microphoneIndex += 1) {
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const channel = channels[microphoneIndex];
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real.fill(0);
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imaginary.fill(0);
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for (let offset = 0; offset < fftSize; offset += 1) {
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real[offset] = (channel[frameStart + offset] ?? 0) * window[offset];
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}
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fftInPlace(real, imaginary);
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const spectrumIndex = frameIndex * microphoneCount + microphoneIndex;
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for (const bin of uniqueBins) {
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const spectrum = spectra.get(bin);
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spectrum.real[spectrumIndex] = real[bin];
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spectrum.imaginary[spectrumIndex] = imaginary[bin];
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}
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completedTransforms += 1;
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if (completedTransforms % transformBatchSize === 0) {
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onProgress?.({ completedTransforms, totalTransforms });
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await yieldToEventLoop();
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throwIfAborted(signal);
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}
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}
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}
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onProgress?.({ completedTransforms, totalTransforms });
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throwIfAborted(signal);
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return { frameCount, microphoneCount, spectra };
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}
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export function binsForBand(band, sampleRate, fftSize) {
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const binWidth = sampleRate / fftSize;
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const firstBin = Math.max(0, Math.ceil(band.minHz / binWidth));
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const lastBin = Math.min(fftSize / 2, Math.floor(band.maxHz / binWidth));
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if (firstBin > lastBin) {
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throw new Error(`${band.minHz}–${band.maxHz} Hz에 해당하는 FFT bin이 없습니다.`);
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}
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return Array.from({ length: lastBin - firstBin + 1 }, (_, index) => firstBin + index);
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}
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