vtt to srt

src/index.ts

@@ -11,6 +11,7 @@ import { showStatus, hideProgress, resetProgress } from './ui/progress';
 import { showPlaylistSelector } from './ui/selector';
 import { DownloadProgress } from './downloader/segment-fetch';
 import { guessFilename } from './utils/filename';
+import { vttToSrt } from './utils/subtitle';
 
 const detectedStreams = new Map<string, { url: string; type: 'm3u8' | 'vtt'; headers?: Record<string, string>; parsed?: ParsedPlaylist }>();
 let panel: HTMLDivElement | null = null;
@@ -95,10 +96,10 @@ function addStreamToUI(url: string, parsed?: ParsedPlaylist): void {
   });
 }
 
-function downloadVtt(blob: Blob, url: string): void {
+function downloadSubtitle(blob: Blob, url: string): void {
   const baseName = guessFilename(url, 'text/vtt');
-  const filename = baseName.replace(/\.(mp4|ts|m4a)$/, '.vtt');
-  log.info(`downloadVtt: ${filename} (${blob.size} bytes)`);
+  const filename = baseName.replace(/\.(mp4|ts|m4a)$/, '.srt');
+  log.info(`downloadSubtitle: ${filename} (${blob.size} bytes)`);
   const urlObj = URL.createObjectURL(blob);
   const target = (typeof unsafeWindow !== 'undefined' ? unsafeWindow : window) as any;
   const doc = target.document || document;
@@ -219,18 +220,19 @@ async function downloadVttStream(url: string, entry: { url: string; type: 'vtt';
         },
         onload: (response: any) => {
           if (response.status >= 200 && response.status < 300) {
-            const text = response.responseText || response.response || '';
-            const blob = new Blob([text], { type: 'text/vtt' });
-            downloadVtt(blob, url);
+            const vttText = response.responseText || response.response || '';
+            const srtText = vttToSrt(vttText);
+            const blob = new Blob([srtText], { type: 'text/plain' });
+            downloadSubtitle(blob, url);
             resolve();
           } else {
             log.error(`downloadVttStream: HTTP ${response.status} for ${url}`);
-            reject(new Error(`VTT download failed: HTTP ${response.status}`));
+            reject(new Error(`Subtitle download failed: HTTP ${response.status}`));
           }
         },
         onerror: (error: any) => {
           log.error(`downloadVttStream: error for ${url}: ${error.error}`);
-          reject(new Error(`VTT download error: ${error.error}`));
+          reject(new Error(`Subtitle download error: ${error.error}`));
         },
       });
     });

src/utils/filename.ts

@@ -4,7 +4,7 @@ export function guessFilename(url: string, mime?: string): string {
 
   if (titleMatch) {
     if (ext === '.vtt' || mime?.includes('vtt')) {
-      return `${titleMatch.name} ${titleMatch.volume}.vtt`;
+      return `${titleMatch.name} ${titleMatch.volume}.srt`;
     }
     return `${titleMatch.name} ${titleMatch.volume}.mp4`;
   }

src/utils/subtitle.ts

@@ -0,0 +1,80 @@
+export function vttToSrt(vttText: string): string {
+  const lines = vttText.replace(/\r\n/g, '\n').replace(/\r/g, '\n').split('\n');
+
+  let idx = 0;
+  while (idx < lines.length && !lines[idx].trim().startsWith('WEBVTT')) {
+    idx++;
+  }
+
+  if (idx >= lines.length) {
+    return vttText;
+  }
+
+  idx++;
+
+  while (idx < lines.length && lines[idx].trim() !== '') {
+    idx++;
+  }
+
+  if (idx < lines.length && lines[idx].trim() === '') {
+    idx++;
+  }
+
+  const remaining = lines.slice(idx);
+  const blocks = splitBlocks(remaining);
+
+  const srtBlocks: string[] = [];
+
+  for (let i = 0; i < blocks.length; i++) {
+    const block = blocks[i];
+    if (block.length === 0) continue;
+
+    const headerLine = block[0].trim();
+    if (!headerLine.includes('-->')) continue;
+
+    const cleaned = cleanCueText(block.slice(1).join('\n'));
+    const timestampLine = headerLine.replace(/\./g, ',');
+
+    srtBlocks.push(`${i + 1}`);
+    srtBlocks.push(timestampLine);
+    srtBlocks.push(cleaned);
+    srtBlocks.push('');
+  }
+
+  return srtBlocks.join('\n').replace(/\n+$/, '\n');
+}
+
+function splitBlocks(lines: string[]): string[][] {
+  const blocks: string[][] = [];
+  let current: string[] = [];
+
+  for (const line of lines) {
+    if (line.trim() === '') {
+      if (current.length > 0) {
+        blocks.push(current);
+        current = [];
+      }
+    } else {
+      current.push(line);
+    }
+  }
+
+  if (current.length > 0) {
+    blocks.push(current);
+  }
+
+  return blocks;
+}
+
+function cleanCueText(text: string): string {
+  return text
+    .replace(/<\/?(?:c|b|i|u|ruby|rt)(?:\s[^>]*)?>/g, '')
+    .replace(/<v[^>]*>/g, '')
+    .replace(/<\s*(?:position|align|line|size|start)\s*=\s*[^>]*>/g, '')
+    .replace(/<\s*\w+:\w+[^>]*>/g, '')
+    .replace(/&nbsp;/g, ' ')
+    .replace(/&lt;/g, '<')
+    .replace(/&gt;/g, '>')
+    .replace(/&amp;/g, '&')
+    .trim();
+}