Why proofreading needs a routine
Proofreading a subtitle file is not the same as proofreading a document. The reader cannot go back and forth at will: the text is tied to sound and picture, appears for a few seconds, and is gone. A mistake may be in the words, in the moment the words appear, or in how they sit on screen. Trying to check all of these at once tends to mean none of them is checked well.
A routine fixes that by splitting the work into passes, each with one job. The order below is a general one that many teams use in some form. Adjust it to your style guide and the importance of the material.
Before you start
Gather what you need so you are not stopping to look things up.
- The subtitle file and the final version of the video it belongs to. Checking against an old edit is a common cause of false alarms and missed errors.
- The style guide: line limits, reading-speed limits, punctuation rules, spelling convention.
- The glossary or notes on names and terms, and a script or source text if there is one.
- The player or tool the audience will actually use, if possible.
Also check the basics: does the file open, is it in one of the expected file formats, and is the language label correct?
Pass 1: read the text alone
Read the subtitles as text, without the video. Look for typos, grammar, punctuation, missing words and sentences that do not make sense. Reading aloud, or at least silently at an even pace, helps the eye catch what it skips on a quick scan. Many reviewers also find it useful to change the display, for example by using a different font size or exporting to a plain text view, so that familiar text looks new.
Mark but do not try to solve everything yet. Make a note of anything that needs the audio to resolve.
Pass 2: compare with the audio
Now watch and listen with the text on. The question is whether the subtitles match what is said, or, for translation, what is meant. Pay attention to:
- Omitted or added words, especially negatives and numbers.
- Sound-alike errors, which are common in automated output.
- Whether text condensation has kept the core meaning.
- Whether speaker identification is clear when voices change.
If the draft came from automatic transcription, expect to spend most of your time here, and see the notes on efficient caption editing. For translation, this pass ideally involves someone fluent in both languages.
Pass 3: names, terms and numbers
Do a dedicated check of proper names, places, specialist vocabulary, dates, amounts and units. These are the words most likely to be wrong and the most costly when they are. Check each against the source or the glossary, and search the file for known misspellings. The reasoning behind this separate pass is explored in the article on names and technical terms.
Pass 4: timing
Watch again, this time paying attention to when text appears and disappears. Ask:
- Does each cue arrive close to the start of the speech, as good subtitle timing requires?
- Is there enough time to read it?
- Do cues follow each other with a visible gap, and without overlap?
- Does the sync hold up through the whole video, including the end?
Spot checks at the beginning, middle and end of the file catch most sync drift. If the video was re-edited after timing, check each changed section carefully.
Pass 5: layout and appearance
Look at how the text sits on screen. Check line length, the number of lines, how lines break, whether text covers important picture content, and whether subtitle legibility holds up against the background. If the text is placed or styled, confirm that the styling is consistent. Where possible, test on a phone as well as a large screen, since small displays reveal legibility problems.
Pass 6: consistency and file checks
Finish with consistency across the file: spelling convention, capitalization, treatment of numbers, how sounds or off-screen voices are marked, and use of italics. Then technical checks: the file opens in the target player, special characters display correctly, the track label is right, and the file name and version number follow the project’s rules.
Some of this can be done with automated checks, which are good at measurable things such as line length, overlapping cues and timing limits. They do not replace reading.
Habits that help
Take breaks. Fatigue is a main reason errors slip through. Short breaks, or a fresh pair of eyes for the second pass, make a real difference.
Use a second reviewer for important material. The person who wrote the subtitles is the worst placed to see their own mistakes. For medical, legal or other sensitive material, a qualified human reviewer should check the text before release.
Keep a log. Record what you changed and why. This helps with disputes, and patterns in your notes show which errors keep recurring and what to add to the checklist.
Fix in order of seriousness. Meaning errors first, then timing, then polish. If time is short, this order protects viewers best.
Do not change the style mid-file. A correction that introduces a new convention creates a new inconsistency. If a rule needs to change, apply it throughout.
Re-check after changes. Every fix can introduce a new error. After editing, re-run at least the quick checks on the affected sections.
When you are done
A file is ready to release when each pass is complete, open queries are resolved or consciously accepted, and the version is clearly identified. No proofreading routine guarantees a flawless result, and it is reasonable to expect that a few small issues remain. The aim is that none of them gets in the way of understanding, and that any which are reported later can be fixed quickly.