Subtitle Shifter fixes captions that are out of sync with the audio. Set a delay in seconds and every cue moves together. If the drift grows the further into the film you go, a frame-rate rescale corrects it. It also converts between SRT and WebVTT.
The subtitle file is read in the page. It is not uploaded, and the retimed file is built on your device.
No. Parsing and re-timing run in JavaScript in the tab. The file stays on your device.
SubRip (.srt) and WebVTT (.vtt), in both directions. SSA/ASS and SBV are not read.
It multiplies every timestamp by the ratio of the two rates, for example 25 to 23.976 for a PAL subtitle used with an NTSC film.
Per-cue position settings are kept. Global style and region blocks are dropped.