I think it would help to set expectations since there are many reasons why a subtitle can’t be synced. And rather than people thinking the feature sucks, it would be great to lay out more of its limitations on the help page.
I’m not sure what the Plex auto-sync is capable of yet. Since it can only adjust up to 30 seconds, I’m going to assume that it can only move the subtitle track as a whole (single-point sync) and can’t adjust the speed (two-point sync) like SubSync and Subtitle Edit can. So, if it can’t do the latter, I suggest adding a bullet point saying that the subtitle file may not be at the same speed as the video. I know “calculated offset is too inconsistent” is kind of the same but not as clearly understood.
I’ve synchronized thousands and thousands of subtitles. Some reasons why it won’t sync are more obvious, like different versions of movies: uncut, director’s cut, extended, etc. Other reasons are more obscure, like commercials and intermissions. Also, sometimes there are regional differences based on where the movie or show is released, or digital vs broadcast versions.
I guess for some people, these reasons don’t need to be stated. But giving people an idea of all the various ways why it won’t sync will give them pause from expecting too much from this feature. I always see people complaining that some auto-sync feature sucks, but the reality is some subtitles just aren’t a match at all.
Correct, it’s currently only using a fixed offset, we’re definitely looking to improve this going forward to make it more robust. We store the original voice activity so tweaking the algorithm is very computationally inexpensive once that step is complete.
We do check and compensate for framerate differences too, i.e. 25 vs 23.976. So this part is technically not true as it would work in this instance as long as the subtitle still matches up to the audio track once it’s been compensated for.
That’s a great list of reasons! I’ll talk to the team so we can improve the the support article to include this detail.
I’m glad we have somebody around here with experience with this and it would be great to hear some feedback once you have had chance to test it out!
