Online Subtitle Tool (Convert / Adjust / Extract / Merge)
Subtitle center for SRT / VTT / ASS conversion, timing shifts and range trimming, embedded subtitle extraction, and soft-subtitle muxing into video. Everything is processed locally in the browser.
Video Subtitle Center: Convert, Adjust, Extract, and Merge in One Place
Working with subtitles usually involves four tasks: converting them to a familiar format, adjusting timing, extracting them from a video, and putting them back into a video. This tool combines all four functions on one page. Subtitle files are parsed and converted directly in the browser, while video-related operations are handled by the built-in engine without re-encoding the video streams.
Subtitle Format Conversion
The tool supports conversion between SRT, WebVTT (VTT), and ASS. After selecting a file, the page automatically detects the input format and shows the subtitle count. Choose the output format to preview the result, then download it after confirmation. ASS styling information is removed when converting to SRT or VTT because those formats do not support the full range of ASS style descriptions. Only subtitle text and timing are retained.
Timing Adjustment
Subtitle synchronization is one of the most common problems: even a half-second delay or advance can make subtitles feel wrong. You can shift all subtitles earlier or later by a fractional number of seconds. If only one section needs adjustment, such as when the first half is correct but the second half is offset, enter a start and end time and the tool will only affect subtitles within that range. The adjusted file can be downloaded automatically, and you can also continue with format conversion.
Extract Embedded Subtitles from Video
Many downloaded videos already contain subtitle tracks. Select a video and click Detect Subtitle Tracks. The page lists the available tracks and language labels such as English or Chinese. Select the track you need and export it as a standalone subtitle file. The operation copies only the subtitle data and does not modify the video stream, so it is very fast and does not affect video quality.
Add Subtitles to Video as Soft Subtitles
Merge adds subtitles as a separate track inside the video container. The video and audio streams are copied without re-encoding, making the operation fast and lossless. After the subtitles are added, compatible players can turn the subtitle track on or off. Burning subtitles directly into the picture requires rendering fonts and libass and is planned for a later stage.
Common Uses
Convert ASS subtitles to SRT for broader player compatibility; convert SRT to VTT for web video; fix subtitles that are out of sync with the video; extract a specific language track from a multi-language video; or add an external subtitle file to a downloaded video without subtitles. All processing takes place on your own device.
Privacy and Data Security
Subtitle parsing, conversion, and timing adjustment are performed completely in the browser without network requests. Video-related extraction and subtitle muxing are also performed locally. When the page is closed or refreshed, the file references are released. Neither subtitle files nor videos are uploaded or stored on the server.
Video Subtitle Center: Convert, Adjust, Extract, and Merge in One Place
- Convert between SRT, WebVTT, and ASS with automatic input-format detection and no file upload
- Shift subtitles earlier or later, including fractional seconds such as +1.5 seconds, and optionally apply the change only within a selected time range
- Detect and list embedded subtitle tracks in local videos, including language labels, then extract the selected track
- Add subtitles as a soft subtitle track that compatible players can turn on or off without re-encoding the video stream
- Preview the complete subtitle output in the target SRT / VTT / ASS format and show the subtitle count before downloading
- Subtitle files and videos are processed locally in the browser, never uploaded, and no registration is required