57 lines
1.4 KiB
TypeScript
57 lines
1.4 KiB
TypeScript
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import { createReadStream } from "fs";
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export type SwapPoint = {
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position_start: number;
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duration: number;
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loud: boolean;
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label: string;
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};
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export default async function (
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file: import("fs").PathLike,
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threshold_at_point: number,
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inertia_samples: number,
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label: string
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): Promise<SwapPoint[]> {
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const stream = createReadStream(file);
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let position = 0;
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const results: SwapPoint[] = [];
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let last_swap_position = 0;
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let keep_loud_until = 0;
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let was_loud_last_time = false;
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return new Promise((resolve, reject) => {
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stream.on("readable", () => {
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let chunk: Buffer | null;
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while ((chunk = stream.read()) !== null) {
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for (let i = 0; i < chunk.byteLength; i++) {
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position++;
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const byte = chunk[i];
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const volume = Math.abs(byte - 128);
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if (position >= keep_loud_until) {
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const is_loud: boolean = volume > threshold_at_point;
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if (is_loud != was_loud_last_time) {
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const swap_point = {
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position_start: last_swap_position,
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duration: position - last_swap_position,
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loud: was_loud_last_time,
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label,
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};
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results.push(swap_point);
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last_swap_position = position;
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was_loud_last_time = is_loud;
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}
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}
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if (volume > threshold_at_point) {
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keep_loud_until = position + inertia_samples;
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}
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}
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}
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});
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stream.on("end", () => {
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resolve(results);
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});
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stream.on("error", reject);
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});
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}
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