@loaders.gl/images/dist/lib/category-api/parse-isobmff-binary.js

Framework-independent loaders and writers for images (PNG, JPG, ...)

// loaders.gl
// SPDX-License-Identifier: MIT
// Copyright (c) vis.gl contributors
// code adapted from https://github.com/sindresorhus/file-type under MIT license
/**
 * Tests if a buffer is in ISO base media file format (ISOBMFF) @see https://en.wikipedia.org/wiki/ISO_base_media_file_format
 * (ISOBMFF is a media container standard based on the Apple QuickTime container format)
 */
export function getISOBMFFMediaType(buffer) {
    // Almost all ISO base media files start with `ftyp` box. (It's not required to be first, but it's recommended to be.)
    if (!checkString(buffer, 'ftyp', 4)) {
        return null;
    }
    // Extra check: test for 8859-1 printable characters (for simplicity, it's a mask which also catches one non-printable character).
    if ((buffer[8] & 0x60) === 0x00) {
        return null;
    }
    // `ftyp` box must contain a brand major identifier, which must consist of ISO 8859-1 printable characters.
    return decodeMajorBrand(buffer);
}
/**
 * brands explained @see https://github.com/strukturag/libheif/issues/83
 * code adapted from @see https://github.com/sindresorhus/file-type/blob/main/core.js#L489-L492
 */
export function decodeMajorBrand(buffer) {
    const brandMajor = getUTF8String(buffer, 8, 12).replace('\0', ' ').trim();
    switch (brandMajor) {
        case 'avif':
        case 'avis':
            return { extension: 'avif', mimeType: 'image/avif' };
        default:
            return null;
    }
    // We don't need these now, but they are easy to add
    // case 'mif1':
    //   return {extension: 'heic', mimeType: 'image/heif'};
    // case 'msf1':
    //   return {extension: 'heic', mimeType: 'image/heif-sequence'};
    // case 'heic':
    // case 'heix':
    //   return {extension: 'heic', mimeType: 'image/heic'};
    // case 'hevc':
    // case 'hevx':
    //   return {extension: 'heic', mimeType: 'image/heic-sequence'};
    // case 'qt':
    //   return {ext: 'mov', mime: 'video/quicktime'};
    // case 'M4V':
    // case 'M4VH':
    // case 'M4VP':
    //   return {ext: 'm4v', mime: 'video/x-m4v'};
    // case 'M4P':
    //   return {ext: 'm4p', mime: 'video/mp4'};
    // case 'M4B':
    //   return {ext: 'm4b', mime: 'audio/mp4'};
    // case 'M4A':
    //   return {ext: 'm4a', mime: 'audio/x-m4a'};
    // case 'F4V':
    //   return {ext: 'f4v', mime: 'video/mp4'};
    // case 'F4P':
    //   return {ext: 'f4p', mime: 'video/mp4'};
    // case 'F4A':
    //   return {ext: 'f4a', mime: 'audio/mp4'};
    // case 'F4B':
    //   return {ext: 'f4b', mime: 'audio/mp4'};
    // case 'crx':
    //   return {ext: 'cr3', mime: 'image/x-canon-cr3'};
    // default:
    // if (brandMajor.startsWith('3g')) {
    //   if (brandMajor.startsWith('3g2')) {
    //     return {ext: '3g2', mime: 'video/3gpp2'};
    //   }
    //   return {ext: '3gp', mime: 'video/3gpp'};
    // }
    // return {ext: 'mp4', mime: 'video/mp4'};
}
/** Interpret a chunk of bytes as a UTF8 string */
function getUTF8String(array, start, end) {
    return String.fromCharCode(...array.slice(start, end));
}
function stringToBytes(string) {
    return [...string].map((character) => character.charCodeAt(0));
}
function checkString(buffer, header, offset = 0) {
    const headerBytes = stringToBytes(header);
    for (let i = 0; i < headerBytes.length; ++i) {
        if (headerBytes[i] !== buffer[i + offset]) {
            return false;
        }
    }
    return true;
}