web/src/decrypt/qmccache.ts

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import {
AudioMimeType,
GetArrayBuffer,
GetCoverFromFile,
GetMetaFromFile,
SniffAudioExt,
SplitFilename
} from "@/decrypt/utils.ts";
import {Decrypt as QmcDecrypt, HandlerMap} 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, _: string)
: Promise<DecryptResult> {
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;
}
let ext = SniffAudioExt(buffer, "");
const newName = SplitFilename(raw_filename)
let audioBlob: Blob
if (ext !== "" || newName.ext === "mp3") {
audioBlob = new Blob([buffer], {type: AudioMimeType[ext]})
} else if (newName.ext in HandlerMap) {
audioBlob = new Blob([buffer], {type: "application/octet-stream"})
return QmcDecrypt(audioBlob, newName.name, newName.ext);
} else {
throw "不支持的QQ音乐缓存格式"
}
const tag = await metaParseBlob(audioBlob);
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(audioBlob),
blob: audioBlob,
mime: AudioMimeType[ext]
}
}