Partial Sync Shifter

The Problem

The regular Sync Shifter fixes files where every cue is off by the same constant amount. But some files have a more complicated problem: they sync fine for the first act, then drift out after a scene break, then drift again later.

This happens when the video file has chapter breaks, when the subtitle was created from a different edit of the film, or when two separately timed subtitle files were stitched together imperfectly. A single global offset can't fix any of these cases — if you shift the whole file by 2 seconds, you fix the middle but break the beginning and end.

How the Partial Sync Shifter Solves It

Instead of one global offset, you define multiple time ranges, each with its own offset. A range tells the tool: "for any subtitle cue whose start time falls between timestamp A and timestamp B, shift it by X seconds." You can add as many ranges as you need. Cues not covered by any range are left untouched.

How to Use It

Step 1 — Upload your file

Drag your .srt file onto the upload zone. The range editor appears below once the file is loaded.

Step 2 — Define your ranges

Each range has three fields:

Field	Description
From	The timestamp where this range begins (e.g. 00:20:00). Leave blank to start from the beginning.
To	The timestamp where this range ends (e.g. 01:10:00). Leave blank to apply to the end of the file.
Offset	Seconds to shift. Positive = forward, negative = backward.

Step 3 — Add more ranges if needed

Click + Add Another Range to define a second or third correction zone.

Step 4 — Download

Click Download Fixed File. The corrected SRT is saved to your computer.

Example

Subtitles are correct for the first 20 minutes, then run 2 seconds late for the rest of the film. Add one range:

From:   00:20:00
To:     (leave blank — applies to end of file)
Offset: -2.0

Two drift points — fine until 15 min, then 1.5s late until 45 min, then 3s late after that:

Range 1 — From: 00:15:00 | To: 00:45:00 | Offset: -1.5
Range 2 — From: 00:45:00 | To: (blank)   | Offset: -3.0

When to Use This vs. the Regular Sync Shifter

Situation	Use
Off by the same amount throughout	Sync Shifter
Fine in places, wrong in others	Partial Sync Shifter
Drifts gradually worse over time	Partial Sync Shifter with multiple small ranges

Tips

• Start broad, then refine. Fix the main problem section first, download, test in your player, then add a second range if needed.
• Timestamps use HH:MM:SS format — no milliseconds needed.
• Ranges don't need to cover the whole file. Uncovered cues pass through unchanged.