Remove hearing-impaired (SDH) subtitles

What this tool does

Subtitle files picked up from around the web are often cluttered, full of hearing-impaired sound descriptions you don't want, styling tags that fight with your player, or lines that flash past too fast to read. This tool tidies a file in three optional ways. Turn on the ones you need and leave the rest alone.

• Strip SDH / sound tags removes hearing-impaired descriptions like [door slams] and (sighs), speaker labels such as JOHN:, and music symbols (♪).
• Strip formatting removes HTML/styling tags like <i> and ASS overrides like {\an8}, and tidies stray blank lines.
• Reading-speed (CPS) check calculates characters-per-second for each cue and flags any that exceed your threshold so you can spot subtitles that flash by too quickly to read.

What is SDH, and why remove it?

SDH stands for "Subtitles for the Deaf and Hard of Hearing." On top of the dialogue, SDH tracks add non-speech information, such as sound effects in brackets like [explosion], music cues marked with ♪, and speaker labels such as MARIA: so you can tell who is talking when it isn't obvious. That information is genuinely valuable if you can't hear the audio, but if you can, it's clutter. Many people download an SDH track simply because it was the only one available for their release, then want it stripped back to plain dialogue. That is exactly what the SDH cleanup does, while leaving the spoken lines untouched.

Why strip formatting tags?

Subtitles can carry styling, such as <i> and <b> tags from SRT, and {\an8} position overrides and font blocks from ASS. Most of the time these render correctly, but some players show the raw tags as literal text on screen, or apply positions and fonts you don't want. Stripping formatting gives you clean, neutral text that displays predictably in any player. If you would rather keep timing and text but change the file's format instead, use the subtitle converter.

Understanding reading speed (CPS)

CPS (characters per second) measures how fast a viewer has to read to keep up with a subtitle. A line of 60 characters shown for 3 seconds is 20 CPS. Go too high and viewers can't finish reading before the line vanishes; the subtitle is technically correct but practically useless.

As a rule of thumb, 15–17 CPS is comfortable, the widely used Netflix ceiling for adult programming is 17 CPS, and most viewers start to struggle past 21 CPS. Set the threshold to match your audience, lower for children's content or learners, higher only if you know your viewers read quickly. The tool lists every cue that exceeds your threshold, with its CPS and text, so you can find and rewrite the offenders. It flags rather than auto-edits, because shortening a line well is a judgement call no tool should make for you. There is a fuller treatment in the guide on subtitle reading speed.

How to use it

• Drop your subtitle file into the box above. The tool detects the format and cue count.
• Tick the cleanups you want and set a CPS threshold if you're checking reading speed.
• Review the preview and the reading-speed report, then download the tidied file.

Is my file uploaded?

No. Cleanup runs entirely in your browser; nothing is uploaded, there is no sign-up, and the original file on your device is never modified. You always download a fresh, cleaned copy.