What it checks
For each subtitle, CueNorm measures the gap since the previous subtitle in the file. A gap shorter than the profile's minimum produces one issue, reported on the later subtitle.
A gap of zero (back-to-back subtitles) is reported when the minimum is above zero. Overlapping subtitles (negative gap) are not reported here: the structural overlap check reports them.
How it is measured
- Gap = start of the subtitle − end of the previous subtitle, in file order, computed exactly.
- The minimum can be declared in milliseconds, seconds or frames. Frames use the frame rate of the profile's writer configuration: at 25 fps,
2fis 0.080 s. - Frame quantization matters: a gap that looks sufficient in milliseconds can shrink once times are snapped to frames by the output format. When CueNorm converts a file, it validates the generated file after quantization, so such a gap is reported too.
- When CueNorm validates a file it has just written, the minimum is first projected onto the output's time grid, rounded down:
2fat 24 fps (0.083 33 s) becomes 0.083 s for a millisecond format such as TTML. A gap of exactly two frames therefore passes after quantization, while a one-frame gap is still reported.
Parameters
| Parameter | Type | Meaning |
|---|---|---|
duration |
duration (ms, s or f) |
Minimum gap between consecutive subtitles |
Example
With duration: 5f at 25 fps (0.200 s), a subtitle starting 3 frames after the previous one ended is reported as Gap of 0.120 s to previous subtitle (minimum 0.200 s).
How to fix
- Shorten the previous subtitle's out time. The
ENSURE_MINIMUM_GAPtransformation does exactly this when the profile allows it, and it never delays a subtitle's in time. - Merge the two subtitles when they belong to the same sentence.