How to fix subtitle timing and sync on a Mac

Subtitles that appear a second too early — or slowly drift out of sync — are the most common subtitle problem. It usually happens when the subtitles were made for a different version of the film, with a different frame rate or an extra logo at the start.

Subtitles are off by the same amount everywhere

Use Shift Times: move every line (or only the selected lines) earlier or later by a fixed amount. Find the right amount by playing the first spoken line and comparing it with its subtitle.

Subtitles drift further out of sync

That is a speed difference, typically 23.976 vs 25 frames per second. Stretch the timing so the first and the last line both match, and everything in between follows.

A few lines are wrong

Select the line and adjust its start and end right in the list, or drag its edges on the audio waveform, where you can see exactly where speech begins. Overlapping lines are flagged so they don't flash on screen.

All of this is in AI Caption & Translate Pro, with a live preview of the subtitle drawn on the video.