How Humlens validates subtitle timing before it reaches post-production

Here's a failure mode that doesn't show up until it's expensive to fix: a subtitle line gets translated accurately, but the translation is long enough that it can't be read in the time the original line was on screen. Nobody catches it during translation, because the translation itself is correct. It surfaces in a review pass, or worse, after export — at which point fixing it means going back to re-time or re-cut, not just re-translate.

Why this happens so often

Languages don't expand at the same rate. German and Finnish translations commonly run 20-30% longer than their English source. Spanish and French sit a bit lower, but still routinely longer than English. None of that is a translation quality problem — it's just how the languages work — but it collides directly with a constraint that has nothing to do with translation: how many characters a viewer can read in the time a line is displayed.

A translator working line-by-line in a spreadsheet has no reliable way to see this. They see text, not a timeline. The overflow is invisible until someone plays the video back with the new subtitles loaded.

What Humlens checks automatically

When a subtitle track is translated, Humlens validates every segment against the original timing constraints from the source file — not a generic reading-speed rule, but the actual display window each line had in the source video. If a translated segment would overflow that window, it's flagged before the file ever reaches a human reviewer, with the specific segment and the amount of overflow called out.

That means the person doing final review isn't scanning an entire transcript looking for problems. They're looking at a short list of segments that need a decision: trim the translation, rephrase it more concisely, or in some cases accept a slightly faster reading pace for a line that's on screen a beat longer than the timestamp suggests.

Why we check before review, not during export

The difference between catching this at translation time versus at export time is the difference between a five-minute fix and a re-cut. Once a video is rendered with burned-in subtitles, or once an SRT file has shipped to a platform, fixing a timing problem means going back through the whole pipeline again. Catching it at the translation step means it's just a text edit.

This is the same principle behind every format Humlens handles: don't wait for a human to find the problem in a full review pass. Check the constraints the format actually has — timing for video, structure for JSON and YAML, length limits for UI strings — as close to the translation step as possible, so review time gets spent on judgment calls instead of hunting for breakage.

See the full video localization workflow, or read about quality assurance across every format.