Gera Tools

SRT Subtitle Cleaner

Remove HTML tags, SDH annotations and ad lines from SRT subtitle files.

Free SRT cleaner. Strips italic, bold and font tags, removes SDH brackets like [music], speaker labels and ad or credit lines such as 'Subtitles by …', then renumbers cues. Pure JavaScript, no upload. It runs free in your browser on Gera Tools, with nothing uploaded.

Last updated Source: Gera Tools

What is SDH and why remove it?

SDH stands for Subtitles for the Deaf and Hard of hearing. It adds non-dialogue cues such as [dramatic music] or (door creaks) and speaker labels. Removing them leaves only spoken dialogue, which some viewers and downstream tools prefer.

The SRT subtitle cleaner strips the clutter out of downloaded subtitles: formatting tags, hearing-description annotations, speaker labels and the promotional or credit lines that release groups inject. The result is a tidy .srt containing just the dialogue, correctly renumbered and ready to use.

What the cleaning rules do

Each cue is parsed into its index, timing and text. The text is then passed through whichever rules you enable, line by line:

  • Strip tags removes HTML-style markup such as <i>, <b> and <font>, plus ASS-style override blocks in curly braces {…}.
  • Remove SDH deletes bracketed descriptions in […] and parenthetical cues in (…), such as [dramatic music playing] or (whispering).
  • Remove speaker labels strips a leading uppercase name followed by a colon, like JOHN: or NARRATOR:.
  • Remove ads drops lines matching known patterns — Subtitles by …, Synced by …, release-group names, and any line containing a URL.

After cleaning, a cue whose text is now empty is discarded, and the surviving cues are renumbered from 1 with their original timings preserved.

Before and after example

Input:

2
00:00:05,200 --> 00:00:08,000
[TENSE MUSIC]

3
00:00:08,000 --> 00:00:11,500
SARAH: <i><font color="#ffff00">Over here, now!</font></i>

4
00:00:12,000 --> 00:00:13,500
(door slams)

5
00:00:14,000 --> 00:00:16,000
Subtitles by RelGrp @ OpenSubs

After cleaning with all rules enabled:

1
00:00:08,000 --> 00:00:11,500
Over here, now!

Cues 2, 4, and 5 were entirely cleaned (music, sound effect, ad), leaving only cue 3’s dialogue. The cue is renumbered to 1 and the timing is preserved exactly.

When to enable or disable each rule

Strip tags should almost always be on. The only exception is if you plan to re-import the subtitle into an editor that reads the tags for styling.

Remove SDH is useful for clean transcripts and for feeding subtitles into translation tools, but turn it off if you need the sound cues for accessibility purposes or are working with a hearing-impaired audience.

Remove speaker labels helps when using subtitles as a plain transcript, but turn it off if you are studying the script and need to follow which character is speaking.

Remove ads is almost always worth enabling — injected promo cues appear at the start or end of many downloaded .srt files and are never part of the original content.

Common issues

Timing drifts after cleaning — timing is never altered by this tool. If your subtitles are out of sync, they were out of sync in the source file; use a subtitle synchronisation tool to apply an offset or stretch.

Multi-line SDH cues — a cue like [MUSIC]\nOver here! will have only the first line removed, leaving the dialogue intact. Purely SDH cues (every line is a description) are dropped.

Non-English SDH formats — some files use guillemets «…» or dashes for hearing descriptions rather than brackets. Those patterns are not currently matched by the SDH rule and will remain in the output. Edit them manually after downloading the cleaned file.

All cleaning runs in your browser — nothing is uploaded and the .srt file never leaves your device.