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Bulk Subtitle Time-Shifter

Shift subtitle timing by ±milliseconds with pasted SRT/VTT text and instant before/after comparison. Localizers fix a 2.5s broadcast delay — paste, shift, copy or download, all local.

Runs on JSZip

100% Local Browser Native

How to Use the Bulk Subtitle Time-Shifter

1. Paste subtitle text

Paste SRT or VTT cues into the left pane (a sample loads by default). Pick .SRT or .VTT output.

2. Set the offset

Enter milliseconds (positive delays, negative advances, step 100) or tap a preset like Delay 1s or Advance 0.5s.

3. Copy or download

Shift timestamps, verify the before/after cue comparison, then copy or download the shifted file.

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Frequently Asked Questions

Why do subtitle batches drift out of sync?

Frame-rate conversions (23.976 vs 25 fps), removed intros, and director's-cut length differences shift every cue equally. A uniform +2500 ms offset fixes a leader change — shift once, verify the first and last cue in the before/after comparison, done.

Positive or negative offset — which?

Positive delays captions (video runs ahead), negative advances them (captions run ahead); negatives clamp at zero so no cue goes negative. Test on the sample: if dialogue appears before lips move, apply a small positive offset in 250 ms steps.

Can episodes need different offsets?

Yes when edits differ per episode — this tool shifts one pasted text per run. Measure each episode's drift (pilot +0 ms, rest +2500 ms) and run one shift per group.

Are my subtitle files uploaded?

No — shifting runs locally in your browser on pasted text with a free copy/download; timing data never leaves your device. Original formatting passes through untouched, with the separator kept per format (, for SRT, . for VTT).

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Last updated October 2026