Why You Can’t See the Problems Yourself
Anyone who makes subtitles knows the content too well — you know what every line says next, so nothing ever feels too fast; you have seen the layout hundreds of times, and your eyes skip the flaws on their own. So the pre-delivery check cannot rely on “watching it again from the top” — it has to be measured against numbers: reading speed, line width, duration, overlaps. Let the figures decide.
The Six Most Common Failures
Ranked by how often they sink a delivery:
- Reading speed too high: viewers cannot finish before the cue cuts, and the whole viewing experience falls apart
- Timeline overlaps: two lines stacking on screen, usually left behind by editing or subtitle merges
- Lines too wide: more than 42 half-width units on landscape, overflowing on small screens
- More than two lines: a three-line block eats half of a phone screen
- Non-standard punctuation: missing spaces between CJK and Latin, wrong full/half-width forms — it looks cheap
- Broken numbering and empty entries: renumbering forgotten after entries were deleted or merged
How to Check
Open Subtitle QC and drop your subtitles in; set the language to auto-detect (27 languages, each with its own rule tiers). The report lists findings at three levels — errors / warnings / hints — each with the entry number and the measured value. Errors must be dealt with (garbled text, timestamp format, end earlier than start, broken numbering); warnings depend on the case (overlaps, reading speed, line width, duration); hints are the polish (line-break position, spaces, punctuation).
What Can Be Fixed with One Click
Numbering, empty entries, rewrapping, spaces and punctuation — anything that leaves the timing untouched — can be fixed automatically; fixes that change the timing (swapping start and end, shifting overlaps, trimming or stretching durations) are unticked by default and should be ticked only after you confirm the impact. Reading speed over the limit has no auto-fix — the machine cannot know which word to cut, so shorten the translation yourself or loosen the timing a bit; see Subtitles Too Fast to Read. After fixing, a fresh check runs automatically, and the report counts only what was genuinely fixed.
While You’re At It
The report page can download a plain-text `.qc.txt` report directly — attach it to the delivery so the other side sees at a glance what you checked. For freshly translated subtitles, run QC before delivery; overall timeline drift is a different kind of problem — if reading speed still fails after checking, see Subtitles Drifting Out of Sync.