Add Detect Media Type by File

src/decrypt/common.js

@@ -3,7 +3,6 @@ const QmcDecrypt = require("./qmc");
 const RawDecrypt = require("./raw");
 const TmDecrypt = require("./tm");
 
-
 export async function CommonDecrypt(file) {
     let raw_ext = file.name.substring(file.name.lastIndexOf(".") + 1, file.name.length).toLowerCase();
     let raw_filename = file.name.substring(0, file.name.lastIndexOf("."));

src/decrypt/ncm.js

@@ -2,7 +2,7 @@ const CryptoJS = require("crypto-js");
 const ID3Writer = require("browser-id3-writer");
 const CORE_KEY = CryptoJS.enc.Hex.parse("687a4852416d736f356b496e62617857");
 const META_KEY = CryptoJS.enc.Hex.parse("2331346C6A6B5F215C5D2630553C2728");
-import {AudioMimeType, GetArrayBuffer} from "./util"
+import {AudioMimeType, DetectAudioExt, GetArrayBuffer} from "./util"
 
 export async function Decrypt(file) {
 
@@ -23,27 +23,16 @@ export async function Decrypt(file) {
     let audioOffset = musicMetaObj.offset + dataView.getUint32(musicMetaObj.offset + 5, true) + 13;
     let audioData = new Uint8Array(fileBuffer, audioOffset);
 
-    for (let cur = 0; cur < audioData.length; ++cur) {
-        audioData[cur] ^= keyBox[cur & 0xff];
-    }
+    for (let cur = 0; cur < audioData.length; ++cur) audioData[cur] ^= keyBox[cur & 0xff];
+
+    if (musicMeta.format === undefined) musicMeta.format = DetectAudioExt(audioData, "mp3");
 
-    if (musicMeta.format === undefined) {
-        const [f, L, a, C] = audioData;
-        if (f === 0x66 && L === 0x4c && a === 0x61 && C === 0x43) {
-            musicMeta.format = "flac";
-        } else {
-            musicMeta.format = "mp3";
-        }
-    }
     const mime = AudioMimeType[musicMeta.format];
 
     const artists = [];
-    musicMeta.artist.forEach(arr => {
-        artists.push(arr[0]);
-    });
-    if (musicMeta.format === "mp3") {
+    musicMeta.artist.forEach(arr => artists.push(arr[0]));
+    if (musicMeta.format === "mp3")
         audioData = await writeID3(audioData, artists, musicMeta.musicName, musicMeta.album, musicMeta.albumPic)
-    }
 
     const musicData = new Blob([audioData], {type: mime});
     return {

src/decrypt/qmc.js

@@ -1,4 +1,4 @@
-import {AudioMimeType, GetArrayBuffer, GetCoverURL, GetFileInfo} from "./util";
+import {AudioMimeType, DetectAudioExt, GetArrayBuffer, GetCoverURL, GetFileInfo} from "./util";
 import {QmcMaskCreate58, QmcMaskGetDefault, QmcMaskDetectMgg, QmcMaskDetectMflac} from "./qmcMask";
 
 const musicMetadata = require("music-metadata-browser");
@@ -15,7 +15,6 @@ const HandlerMap = {
     "tkm": {handler: QmcMaskGetDefault, ext: "m4a", detect: false}
 };
 
-//todo: use header to detect media type
 export async function Decrypt(file, raw_filename, raw_ext) {
     if (!(raw_ext in HandlerMap)) return {status: false, message: "File type is incorrect!"};
     const handler = HandlerMap[raw_ext];
@@ -27,14 +26,16 @@ export async function Decrypt(file, raw_filename, raw_ext) {
         seed = handler.handler(audioData);
         keyData = fileData.slice(-0x170);
         if (seed === undefined) seed = await queryKeyInfo(keyData, raw_filename, raw_ext);
-        if (seed === undefined) return {status: false, message: "此格式仅提供实验性支持！"};
+        if (seed === undefined) return {status: false, message: raw_ext + "格式仅提供实验性支持！"};
     } else {
         audioData = fileData;
         seed = handler.handler(audioData);
     }
     const dec = seed.Decrypt(audioData);
 
-    const mime = AudioMimeType[handler.ext];
+    const ext = DetectAudioExt(dec, handler.ext);
+    const mime = AudioMimeType[ext];
+
     const musicData = new Blob([dec], {type: mime});
 
     const tag = await musicMetadata.parseBlob(musicData);
@@ -45,7 +46,7 @@ export async function Decrypt(file, raw_filename, raw_ext) {
         status: true,
         title: info.title,
         artist: info.artist,
-        ext: handler.ext,
+        ext: ext,
         album: tag.common.album,
         picture: GetCoverURL(tag),
         file: URL.createObjectURL(musicData),

src/decrypt/qmcMask.js

@@ -110,10 +110,7 @@ export function QmcMaskDetectMflac(data) {
     for (let block_idx = 0; block_idx < search_len; block_idx += 128) {
         try {
             mask = new QmcMask(data.slice(block_idx, block_idx + 128));
-            if (!mask.Decrypt(data.slice(0, FLAC_HEADER.length))
-                .every((val, idx) => {
-                    return val === FLAC_HEADER[idx];
-                })) break;
+            if (!IsBytesEqual(FLAC_HEADER, mask.Decrypt(data.slice(0, FLAC_HEADER.length)))) break;
         } catch (e) {
         }
     }

src/decrypt/raw.js

@@ -1,17 +1,23 @@
 const musicMetadata = require("music-metadata-browser");
-import {GetCoverURL, GetFileInfo, AudioMimeType} from "./util";
+import {GetCoverURL, GetFileInfo, AudioMimeType, DetectAudioExt, GetArrayBuffer} from "./util";
 
-export async function Decrypt(file, raw_filename, raw_ext) {
+export async function Decrypt(file, raw_filename, raw_ext, detect = true) {
+    let ext = raw_ext;
+    if (detect) {
+        const buffer = new Uint8Array(await GetArrayBuffer(file));
+        ext = DetectAudioExt(buffer, raw_ext);
+        if (ext !== raw_ext) file = new Blob([buffer], {type: AudioMimeType[ext]})
+    }
     const tag = await musicMetadata.parseBlob(file);
     const info = GetFileInfo(tag.common.artist, tag.common.title, raw_filename);
     return {
         status: true,
         title: info.title,
         artist: info.artist,
-        ext: raw_ext,
+        ext: ext,
         album: tag.common.album,
         picture: GetCoverURL(tag),
         file: URL.createObjectURL(file),
-        mime: AudioMimeType[raw_ext]
+        mime: AudioMimeType[ext]
     }
 }

src/decrypt/tm.js

@@ -10,5 +10,5 @@ export async function Decrypt(file, raw_filename) {
         audioData[cur] = TM_HEADER[cur];
     }
     const musicData = new Blob([audioData], {type: "audio/mp4"});
-    return await RawDecrypt(musicData, raw_filename, "m4a")
+    return await RawDecrypt(musicData, raw_filename, "m4a", false)
 }

src/decrypt/util.js

@@ -1,4 +1,7 @@
-export const FLAC_HEADER = [0x66, 0x4C, 0x61, 0x43, 0x00];
+export const FLAC_HEADER = [0x66, 0x4C, 0x61, 0x43];
+export const MP3_HEADER = [0x49, 0x44, 0x33];
+export const OGG_HEADER = [0x4F, 0x67, 0x67, 0x53];
+export const M4A_HEADER = [0x66, 0x74, 0x79, 0x70];
 export const AudioMimeType = {
     mp3: "audio/mpeg",
     flac: "audio/flac",
@@ -45,7 +48,19 @@ export function GetCoverURL(metadata) {
 }
 
 export function IsBytesEqual(first, second) {
+    // if want wholly check, should length first>=second
     return first.every((val, idx) => {
         return val === second[idx];
     })
 }
+
+/**
+ * @return {string}
+ */
+export function DetectAudioExt(data, fallbackExt) {
+    if (IsBytesEqual(MP3_HEADER, data.slice(0, MP3_HEADER.length))) return "mp3";
+    if (IsBytesEqual(FLAC_HEADER, data.slice(0, FLAC_HEADER.length))) return "flac";
+    if (IsBytesEqual(OGG_HEADER, data.slice(0, OGG_HEADER.length))) return "ogg";
+    if (IsBytesEqual(M4A_HEADER, data.slice(4, 8))) return "m4a";
+    return fallbackExt;
+}