@4bitlabs/dct/dist/dct.js

Discrete cosine transform algorithms in js and ts

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.dct = dct;
exports.idct = idct;
function dct(vIn, vOut) {
    const N = vIn.length;
    const sqrt2_n = Math.sqrt(2 / N);
    let sum;
    for (let k = 0; k < N; k++) {
        sum = 0;
        for (let n = 0; n < N; n++) {
            sum += vIn[n] * Math.cos((Math.PI * (n + 0.5) * k) / N);
        }
        const s = k === 0 ? 1 / Math.SQRT2 : 1;
        vOut[k] = s * sqrt2_n * sum;
    }
}
function idct(vIn, vOut) {
    const N = vIn.length;
    const sqrt2_n = Math.sqrt(2 / N);
    let sum;
    for (let n = 0; n < N; n++) {
        sum = 0;
        for (let k = 0; k < N; k++) {
            const s = k === 0 ? Math.SQRT1_2 : 1;
            sum += s * vIn[k] * Math.cos((Math.PI * (n + 0.5) * k) / N);
        }
        vOut[n] = sqrt2_n * sum;
    }
}
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