fix(#1): 重构字幕下载逻辑

lib/index.js

@@ -1,6 +1,5 @@
 const axios = require('axios')
 const fs = require('fs')
-const vtt2srt = require('node-vtt-to-srt')
 
 class VideoDownloader {
   constructor (config) {
@@ -33,14 +32,15 @@ class VideoDownloader {
                 const fileName = `${chapterNumber}-${title}.${subtitle.language}`
                 console.log(`开始下载:${fileName}.vtt`)
                 await this.downloadFile(subtitle.link, `${fileName}.vtt`)
-                console.log('vtt转srt')
+                console.log('vtt转srt...')
                 try {
-                  fs.createReadStream(`${fileName}.vtt`)
-                    .pipe(vtt2srt())
-                    .pipe(fs.createWriteStream(`${folderName}/${fileName}.srt`))
+                  const source = fs.readFileSync(`${fileName}.vtt`, 'UTF-8')
+                  const srt = this.vtt2srt(source)
+                  fs.writeFileSync(`${folderName}/${fileName}.srt`, srt, 'UTF-8')
                   console.log(`格式转换成功,删除${fileName}.vtt`)
                   fs.unlinkSync(`${fileName}.vtt`)
                 } catch (error) {
+                  console.log(error.message)
                   console.log(`${fileName}.vtt 格式转换失败`)
                 }
               }
@@ -113,6 +113,27 @@ class VideoDownloader {
       writer.on('error', reject)
     })
   }
+
+  vtt2srt (source) {
+    const vttRemoval = /(WEBVTT\s+)(\d{2}:)/mg
+    const itemMatcher = /((\d{2}:)?\d{2}:\d{2})\.(\d{3}\s+)-->\s+((\d{2}:)?\d{2}:\d{2})\.(\d{3}\s*)/mg
+    const separator = '\n'
+    let srtString = source.replace(vttRemoval, '$2')
+    let lineCounter = 0
+    srtString = srtString.replace(itemMatcher, function (match) {
+      lineCounter++
+      return lineCounter + separator + match.replace(itemMatcher, (match, p1, p2, p3, p4, p5, p6) => {
+        if (p1.split(':').length === 2) {
+          p1 = '00:' + p1
+        }
+        if (p4.split(':').length === 2) {
+          p4 = '00:' + p4
+        }
+        return `${p1},${p3} --> ${p4},${p6}`
+      })
+    })
+    return srtString
+  }
 }
 
 exports.VideoDownloader = VideoDownloader

package.json

@@ -12,8 +12,7 @@
   "author": "",
   "license": "ISC",
   "dependencies": {
-    "axios": "^0.21.1",
-    "node-vtt-to-srt": "^1.0.1"
+    "axios": "^0.21.1"
   },
   "devDependencies": {
     "eslint": "^7.30.0",