Support bold, italic and underline in SRT

README.md

@@ -30,7 +30,6 @@ premium subscription!**
 ### Pending Implementation
 
 * Detect and write the appropriate video extension (instead of hard-code mp4).
-* Improve SRT support for i, b and u.
 * Add ASS support.
 * Add muxing (MP4+ASS=MKV).
 * Add series API to download an entire series rather than per-episode.

src/subtitle/formats/srt.js

@@ -2,7 +2,7 @@
 var xml2js = require('xml2js');
 
 /**
- * Converts an input buffer to a SRT subtitle.
+ * Converts an input buffer to a SubRip subtitle.
  * @param {Buffer|string} input
  * @param {function(Error, string=)} done
  */
@@ -62,7 +62,12 @@ function _suffix(value, length) {
  * @returns {string}
  */
 function _text(text) {
-  return text.replace(/{[^}]+}/g, '').replace(/\\n/ig, '\n');
+  return text
+    .replace(/{\\i1}(.+){\\i0}/g, '<i>$1</i>')
+    .replace(/{\\b1}(.+){\\b0}/g, '<b>$1</b>')
+    .replace(/{\\u1}(.+){\\u0}/g, '<u>$1</u>')
+    .replace(/{[^}]+}/g, '')
+    .replace(/\\n(\s+)?/ig, '\n');
 }
 
 /**