web/src/decrypt/ncmcache.ts

import { AudioMimeType, GetArrayBuffer, GetCoverFromFile, GetMetaFromFile, SniffAudioExt } from '@/decrypt/utils';

import { DecryptResult } from '@/decrypt/entity';

import { parseBlob as metaParseBlob } from 'music-metadata-browser';

export async function Decrypt(file: Blob, raw_filename: string, raw_ext: string): Promise<DecryptResult> {
  const buffer = new Uint8Array(await GetArrayBuffer(file));
  let length = buffer.length;
  for (let i = 0; i < length; i++) {
    buffer[i] ^= 163;
  }
  const ext = SniffAudioExt(buffer, raw_ext);
  if (ext !== raw_ext) file = new Blob([buffer], { type: AudioMimeType[ext] });
  const tag = await metaParseBlob(file);
  const { title, artist } = GetMetaFromFile(raw_filename, tag.common.title, String(tag.common.artists || tag.common.artist || ""));

  return {
    title,
    artist,
    ext,
    album: tag.common.album,
    picture: GetCoverFromFile(tag),
    file: URL.createObjectURL(file),
    blob: file,
    mime: AudioMimeType[ext],
  };
}