@juspay/neurolink/dist/utils/isoBmff.js

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/**
 * Shared ISO-BMFF (`ftyp`) image-brand detection.
 *
 * FileDetector and ImageProcessor must use the same brand tables and declared
 * box boundary when classifying AVIF, HEIC, and structural HEIF brands. Keeping
 * the scan here prevents the two consumers from drifting as new brands are
 * added.
 */
export const AVIF_FTYP_BRANDS = new Set(["avif", "avis", "avio"]);
export const HEIC_FTYP_BRANDS = new Set([
    "heic",
    "heix",
    "hevc",
    "hevx",
    "heim",
    "heis",
    "hevm",
    "hevs",
]);
export const HEIF_STRUCTURAL_FTYP_BRANDS = new Set(["mif1", "msf1"]);
/**
 * Whether the buffer starts with an ISO-BMFF `ftyp` box signature.
 */
export function hasFtypBoxSignature(input) {
    return (input.length >= 8 &&
        input[4] === 0x66 &&
        input[5] === 0x74 &&
        input[6] === 0x79 &&
        input[7] === 0x70);
}
/**
 * Read compatible brands without scanning past the declared `ftyp` box.
 */
export function getCompatibleFtypBrands(input) {
    const compatibleBrands = new Set();
    if (input.length < 20) {
        return compatibleBrands;
    }
    const declaredBoxSize = input.readUInt32BE(0);
    const boxEnd = declaredBoxSize === 0
        ? input.length
        : Math.min(input.length, declaredBoxSize);
    for (let offset = 16; offset + 4 <= boxEnd; offset += 4) {
        compatibleBrands.add(input.toString("latin1", offset, offset + 4));
    }
    return compatibleBrands;
}
function hasFtypBrand(compatibleBrands, candidates) {
    for (const brand of compatibleBrands) {
        if (candidates.has(brand)) {
            return true;
        }
    }
    return false;
}
/**
 * Return the image MIME type encoded by an ISO-BMFF `ftyp` box, or null when
 * the box belongs to a non-image ISO-BMFF flavor.
 */
export function detectIsoBmffImageMimeType(input) {
    if (input.length < 12 || !hasFtypBoxSignature(input)) {
        return null;
    }
    const brand = input.toString("latin1", 8, 12);
    if (AVIF_FTYP_BRANDS.has(brand)) {
        return "image/avif";
    }
    if (HEIC_FTYP_BRANDS.has(brand)) {
        return "image/heic";
    }
    if (!HEIF_STRUCTURAL_FTYP_BRANDS.has(brand)) {
        return null;
    }
    const compatibleBrands = getCompatibleFtypBrands(input);
    if (hasFtypBrand(compatibleBrands, HEIC_FTYP_BRANDS)) {
        return "image/heif";
    }
    if (hasFtypBrand(compatibleBrands, AVIF_FTYP_BRANDS)) {
        return "image/avif";
    }
    return null;
}