Hacker News Reader

Comment by scrollaway | Hacker News Reader

I wish VLC, plex, video players in general had the ability to automatically sync subs to audio. (automatically, not manually)

We have the technology; everything we need to do this exists. It's just not done automatically, and when using slightly off-sync subs, you have to fiddle with sub timing for ages until you find the right sync. Even more so when the subtitles have different off-sync issues for the whole movie/episode.

View on HN

And you need to do the manual thing so rarely, that you always forget that does the delay need to be positive or negative if the subtitles are fast. =)

And then VLC does this weird freeze thing to catch up that can't be aborted, so if you accidentally type an extra zero into delay, good luck waiting for that to stop haha. Usually faster to just restart the damn thing.

Try SubSync, open source movie subtitle synchronization app. Build in feature like this in VLC would be awesome.

https://subsync.online/

Discussion on HN (4 months ago): https://news.ycombinator.com/item?id=29794153

Yes I was in that thread hehe :)

Given our capabilities, it's really a straightforward thing to do. YouTube does it automatically (you drop in your script with the video, it auto-syncs everything).

It could even be done for when the language doesn't match, given an auto-translation pass and some heuristics.

I've used https://github.com/kaegi/alass and sometimes it works, sometimes it doesn't. It's not an easy problem to address automatically...

Video players wouldn't want that in their codebase, maybe if it was available as a C library.

I can vouch for alass working quite well about 70% of the time.

It's very convenient when it does.

But that's the "job" of releasers? I have had to manually sync subs to audio maybe a few times over the past two decades...

I don't know about 'automatic', but in mpv[1] you have this:

> Ctrl+Shift+Left and Ctrl+Shift+Right

> Adjust subtitle delay so that the next or previous subtitle is displayed now. This is especially useful to sync subtitles to audio.

This works in 9/10 cases. :)

----

[1]https://mpv.io/

I think this is what the OP refers to with "fiddle around for ages". I know the problem not with subs, but when audio is off related to the image. And of course the problem is rare enough that I am never "in training", and have to find a remarkable spot first (e.g. door slam shut or a suitable spot in dialogue), then think about going backwards or forwards, guess the amount, etc. etc. :)

If the whole subtitle file is out of sync (e.g. every line is late 2s), one shortcut is all it takes. In that 1/10 case, you do need to 'fiddle around for ages', but given that all other options (e.g. SubtitleEdit[1]) are way more complicated and time consuming, mpv is all I could suggest. For the problem with audio and image being out-of-sync, I have no idea :)

---

[1] https://www.nikse.dk/subtitleedit

For AV sync you can do this in the receiver (and some devices with e.g. Bluetooth support for speakers) because it's not really a problem with the source material (typically anyway) it's just something that does need tuning to the room & hardware.

I use Bazarr to automate downloading of subtitles for my movies and TV shows, and it integrates subsync. Works 99% of the time, if it doesn't I find the subs for that particular series are consistently offsync by 1.0s which is easy to fix with decent media players.

Reply on news.ycombinator.com