How to convert SRT subtitles to SUB and IDX subtitles

Learn how to convert SRT subtitles to SUB and IDX subtitles in Windows 10 and 11 with this step-by-step tutorial.

SRT (.srt) short for SubRipText is a commonly used text-based subtitle format that contains formatted lines of plain text in groups separated by a blank line.

SUB (.sub) short for VobSub is an image-based subtitle format that contains images extracted from a DVD and IDX (.idx) contains the additional information that belongs to the SUB subtitle format.

How to convert SRT subtitles to SUB and IDX subtitles

For this, we'll be using a free small portable program called AVIAddXSubs (which you even don't need to install).

1. Click here to download AVIAddXSubs.

2. Unzip the downloaded file.

Unzip file

3. Open the AVIAddXSubs folder.

4. Double-click on AVIAddXSubs.exe to open it.

Open AVIAddXSubs

5. Click on Configuration 1 at the top of AVIAddXSubs.

6. Check the Idx/Sub (avi,mkv,mp4) option.

AVIAddXSubs Idx/Sub option

7. Click on Create XSUB or Idx/Sub at the top.

8. At File Name(s) (.avi or .srt or .idx) Or Folder(s)..., you click on the [...] button.

AVIAddXSubs browse button

A “Open” window will appear.

9. Within this window, you go to the location on your computer where the SRT subtitle file is.

10. Click on the AVI Files (*.avi) selection menu button and select SRT Files (*.srt).

Select SRT Files

11. Select the SRT file.

12. Click on the Open button.

Open a SRT subtitle file in AVIAddXSubs

13. Click on the Start button at the bottom of the window.

AVIAddXSubs will now convert your SRT subtitle file to SUB and IDX subtitle files.

AVIAddXSubs will save the new subtitle files in the same folder as the SRT subtitle file.