web/src/decrypt/xm.js

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import {AudioMimeType, GetArrayBuffer, GetFileInfo, GetMetaCoverURL, IsBytesEqual} from "./util";
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import {Decrypt as RawDecrypt} from "./raw";
const musicMetadata = require("music-metadata-browser");
const MagicHeader = [0x69, 0x66, 0x6D, 0x74]
const MagicHeader2 = [0xfe, 0xfe, 0xfe, 0xfe]
const FileTypeMap = {
" WAV": ".wav",
"FLAC": ".flac",
" MP3": ".mp3",
" A4M": ".m4a",
}
export async function Decrypt(file, raw_filename, raw_ext) {
const oriData = new Uint8Array(await GetArrayBuffer(file));
if (!IsBytesEqual(MagicHeader, oriData.slice(0, 4)) ||
!IsBytesEqual(MagicHeader2, oriData.slice(8, 12))) {
if (raw_ext === "xm") {
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return {status: false, message: "此xm文件已损坏"}
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} else {
return await RawDecrypt(file, raw_filename, raw_ext, true)
}
}
let typeText = (new TextDecoder()).decode(oriData.slice(4, 8))
if (!FileTypeMap.hasOwnProperty(typeText)) {
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return {status: false, message: "未知的xm文件类型"}
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}
let key = oriData[0xf]
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let dataOffset = oriData[0xc] | oriData[0xd] << 8 | oriData[0xe] << 16
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let audioData = oriData.slice(0x10);
let lenAudioData = audioData.length;
for (let cur = dataOffset; cur < lenAudioData; ++cur)
audioData[cur] = (audioData[cur] - key) ^ 0xff;
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const ext = FileTypeMap[typeText];
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const mime = AudioMimeType[ext];
let musicBlob = new Blob([audioData], {type: mime});
const musicMeta = await musicMetadata.parseBlob(musicBlob);
if (ext === "wav") {
//todo:未知的编码方式
musicMeta.common.album = "";
musicMeta.common.artist = "";
musicMeta.common.title = "";
}
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let _sep = raw_filename.indexof("_") === -1 ? "-" : "_"
const info = GetFileInfo(musicMeta.common.artist, musicMeta.common.title, raw_filename, _sep);
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const imgUrl = GetMetaCoverURL(musicMeta);
return {
status: true,
title: info.title,
artist: info.artist,
ext: ext,
album: musicMeta.common.album,
picture: imgUrl,
file: URL.createObjectURL(musicBlob),
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mime: mime,
rawExt: "xm"
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}
}