Subtitles Out of Sync

I’m new to subtitles so forgive the possible naivety of this question.

But sometimes I find that subtitles are off by as many as several seconds when watching a film in Infuse. And even if I adjust the time offset so that they are back in sync, at some point I find that they get out of sync again.

I should also say that I don’t really understand the scale/unit of the Time Offset setting. If I boost it to say 20.5, what does that mean? 20.5 milliseconds? And just to confirm, that would actually delay the appearance of a subtitle by 20.5 units, right?

Any help or pointers would be greatly appreciated!

Welcome to the forum.

Are these embedded subtitles, your own external subtitles, or subtitles downloaded from within Infuse?

One thing to keep in mind is that subtitles timings can vary based on the frames per second (FPS) of the video. For example, movies released in the US are encoded at 24 FPS while movies released in the UK (and some other parts of the world) are encoded at 25. Using a 25fps subtitle with a 24fps video (and vice versa) will cause the subtitles to become increasingly out of sync as the movie goes one.

On a related note, in the 5.4.3 update we just happened to add a note about the FPS of each available subtitle download from OpenSubttiles, and this will be listed in the OpenSubtitles download list. You’ll just want to check and ensure you’re downloading one that matches your video (or just download one with a different FPS if you are experiencing trouble to see if it helps).

Thanks for the insight James. In answer to your question: these are subtitles that I’m downloading from within Infuse.

It makes sense that mismatched fps rates would cause subtitles to go out of sync. I’ll keep an eye on this in the future. Also, good to hear that Infuse is adding info on that. Very helpful!

Are you able to help me better understand the Time Offset variable unit of measurement? I feel like that in particular is conceptually confusing. Thanks!

The Timing Offset option changes when subtitles appear.

So, for example, if you notice your subtitles are appearing 5 seconds late, you would want to set your offset to -5.00. The plus/minus buttons can be used to go up/down in 0.25s increments, or you can tap the number text to type in a specific value.

Will the offset feature become available on the Apple TV as well?

It is, assuming it’s not embedded subtitles.
You highlight the subtitle track then on the right hand side you set the size etc of the subtitles. The last option is the offset.

Ah, that explains a lot. Bummer, I always use embedded ones. Perhaps it has something to do with the format of embedded subtitles being harder to manipulate. Thanks anyway!