Fix subtitle drift
Use two known speech starts to correct subtitles that gradually drift out of sync.
Check the size of the error
Play a line early in the video and another near the end. If the delay grows or shrinks steadily, pick clear speech starts at both ends.
Set two smooth anchors
Match each cue start to its real start in the video. If a cue at 00:01:00.000 belongs at 00:01:01.000 and one at 00:11:00.000 belongs at 00:11:05.000, the line halfway between them moves by three seconds. Preview a line in the middle and add an anchor if its timing still needs repair.
Before the first and after the last anchor, CueMend uses the closest offset. Place anchors close to both ends if drift continues there.