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forked from um/web
web/src/decrypt/qmccache.ts

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import {AudioMimeType, GetArrayBuffer, GetCoverFromFile, GetMetaFromFile, SniffAudioExt} from "@/decrypt/utils.ts";
import {Decrypt as QmcDecrypt} from "@/decrypt/qmc";
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, detect: boolean = true)
: Promise<DecryptResult> {
let ext = raw_ext;
if (detect) {
const buffer = new Uint8Array(await GetArrayBuffer(file));
let length = buffer.length
for (let i = 0; i < length; i++) {
buffer[i] ^= 0xf4
if(buffer[i] <= 0x3f)buffer[i] = buffer[i] * 4;
else if(buffer[i] <= 0x7f)buffer[i] = (buffer[i] - 0x40) * 4 + 1;
else if(buffer[i] <= 0xbf)buffer[i] = (buffer[i] - 0x80) * 4 + 2;
else buffer[i] = (buffer[i] - 0xc0) * 4 + 3;
}
ext = SniffAudioExt(buffer, raw_ext);
if (ext !== raw_ext) file = new Blob([buffer], {type: AudioMimeType[ext]})
else {
file = new Blob([buffer], {type: "application/octet-stream"})
let ext = raw_filename.substring(file.name.lastIndexOf(".") + 1, file.name.length).toLowerCase();
if (ext !== "mgg" && ext !== "mflac") throw "不支持的QQ音乐缓存格式" + raw_filename + ".cache";
return QmcDecrypt(file, raw_filename, ext+".cache");
}
}
const tag = await metaParseBlob(file);
const {title, artist} = GetMetaFromFile(raw_filename, tag.common.title, tag.common.artist)
return {
title,
artist,
ext,
album: tag.common.album,
picture: GetCoverFromFile(tag),
file: URL.createObjectURL(file),
blob: file,
mime: AudioMimeType[ext]
}
}