How does subtitle retiming work?

Subtitle retiming shifts every cue's start and end timestamps by a specified offset in milliseconds or seconds. It can also stretch or compress timestamps to correct framerate drift (such as 23.976 fps to 24 fps or 25 fps).

What is the difference between SRT and WebVTT?

SRT (SubRip) uses commas for millisecond delimiters (00:01:23,456) and numbered cue headers. WebVTT uses periods (00:01:23.456), starts with WEBVTT, and is the native W3C subtitle standard for HTML5 video elements.

Are my subtitle files uploaded to a remote server?

No. All subtitle parsing, editing, retiming, conversion, and exporting happen 100% locally in your browser using client-side JavaScript. Your dialogue and video data never leave your computer.

Free Online Subtitle Editor & Retimer (SRT & WebVTT)

Understanding Subtitle Synchronization & Formats

Subtitles are essential for accessibility, international translation, and SEO indexing of multimedia content. However, moving subtitles across different media players, streaming encoders, and video cuts frequently leads to audio drift or timing offset bugs.

Common Causes of Subtitle Desynchronization

Linear Time Shift: The subtitle begins several seconds before or after the dialogue begins (commonly caused by studio logos, intro clips, or commercial leader cuts). Easily fixed by adding or subtracting a constant offset.
Framerate Mismatch (Progressive Drift): Subtitles that gradually drift out of sync over the course of a film are typically caused by framerate conversion errors—e.g. video recorded at 23.976 fps played against subtitles timed at 25 fps or 24 fps. Scaling by 1.0427x or 0.959x resolves progressive drift.
Format Differences: SubRip (.srt) uses commas (00:01:25,500) for millisecond fractions, while HTML5 WebVTT (.vtt) requires decimal periods (00:01:25.500). Our editor parses both transparently.