srt starts OK, goes off track, comes back at the end. why, and how to fix?

[gallant205]

Situation: I'll have an mp4 or an mkv without an attached srt. I'll go get one at Addic7ed.com and try it. Frequently, sync is off, usually a problem with 23.975 to 25 or vice versa, whatever, so I use Subtitle Edit to visually Start and End the srt to the right video parts. But then, in just this one TV series episodes, the weirdest thing happens- the srt slowly goes out of sync and stays that way in the middle, and then slowly at the end catches up to the right sync.

This happens in every single TV episode of this show.

You know, it would really be nice if there was a program that would load the srt lines, run the video, and let you tag an srt line at the right moment, all the way through the video. In some cases, I'd do it if the video were important enough. But I've never seen anything like that.

Anyway, why might this be happening, and is there any Easy way to fix? (besides getting another copy of the show- I tried that, with the same results)

[jagabo]

Something was cut or added somewhere in the middle of the movie. You'll have to work in segments.

[johns0]

Or get the proper srt for the video.

[jagabo]

Keep in mind that it's very common for releases in different parts of the world to be cut differently. With segments removed or added to suit local sensibilities.

[Nikse]

In Subtitle Edit, you can right-click on the waveform and choose "Seek silence"... it's often at these zero-volume-places that you need to sync.
Then select the first unsync'ed line, and place the video position in the waveform where the sub should start and click "Set start and offset the rest" (or do Ctrl+shift+left-mouse-button-click).

[orsetto]

Addic7ed is a great resource, but not as good as it used to be: the site is festering with suspicious popups, direct search functionality has been crippled for months, and they no longer offer quite as many re-syncs. So this issue of imperfect SRT matchups for certain files has come up more and more of late, esp with international co-production series that air a year earlier in Europe than North America (if at all). Addic7ed will often do just the first release, which may be terrible quality, then never follow up with resyncs when the improved video files appear a week or a month later. So if you want usable SRTs for those, DIY updating is the only alternative (unless you can find a compatible update posted to a different SRT site).

In my experience, this kind of timing drift is due to the file including longer-than-usual dead air between commercial breaks, or it includes fade out/fade in where the commercials/ads were removed. The only way to fix this is by finding the closest SRT match on Addic7ed, then manually locating the first commercial break, timing the sync drift, then adjusting the speedup or delay of all the subtitles up to that point in a subtitle editing app (so the video+SRT regains sync after that commercial break, until drifting again at the next). Find the next break, and repeat. Then the next, and the next, until you reach the end. Tedious, but effective. Usually sync is off by about 3-4 seconds at each segment break.