Surely you can do much better than this using a speech recogniser?
Show HN: Automatically synchronize subtitles with video
11–20 of 129 posts
Re: Show HN: Automatically synchronize subtitles with video
#12This problem is called forced alignment. YouTube's subtitler does it for you. If you don't want to upload your video and subtitles, here are some other tools that will work: https://github.com/pettarin/forced-alignment-tools/blob/mast...
Cool! It looks to me like most of those approaches are a lot more sophisticated and work even when the text doesn't have any time annotations. At a first glance, it looks like the major downside is that these approaches are geared toward particular target languages. Subsync's advantage is its simplicity: by limiting the acoustic analysis part to simple voice detection, it can perform alignment between subtitles and audio/video in different languages, which is great for when you want to watch a TV episode in another language, but your video includes the previous episode's recap and your subtitles do not (or vice-versa). I'll definitely be taking a deeper look at these to see if there's any ideas / functionality that can be further incorporated.
Re: Show HN: Automatically synchronize subtitles with video
#13Sorry for the dumb question, but what exactly does this do? `subsync reference.srt -i unsynchronized.srt -o synchronized.srt` I mean, I already have a synchronized srt file, so what would I be syncing here?
Great question. The main use case I can think of is when reference.srt and unsynchronized.srt are in different languages, and you want to eventually merge them into a single dual-language subtitle file.
EDIT: Oh, I should also mention that you don't need a reference.srt -- it can look at the video directly and use that as a reference.
Re: Show HN: Automatically synchronize subtitles with video
#14"Although it can usually work if all you have is the video file, it will be faster (and potentially more accurate) if you have a correctly synchronized "reference" srt file, in which case you can do the following: subsync reference.srt -i unsynchronized.srt -o synchronized.srt" I really don't understand what the reference.srt is supposed to be here. Edit: If I have a "reference" which is synchronized why do I have to…
I believe it's a typo and should read "Although it can usually work if all you have is the subtitles file [...]".
This means that you would use a reference file that would allow you to synchronize your subtitles.
Re: Show HN: Automatically synchronize subtitles with video
#15Sorry for the dumb question, but what exactly does this do? `subsync reference.srt -i unsynchronized.srt -o synchronized.srt` I mean, I already have a synchronized srt file, so what would I be syncing here?
I'm guessing `synchronized.srt` is just the name of the output file.
I think they were referring to the fact that "reference.srt" would already be synchronized.
Re: Show HN: Automatically synchronize subtitles with video
#16Sorry for the dumb question, but what exactly does this do? `subsync reference.srt -i unsynchronized.srt -o synchronized.srt` I mean, I already have a synchronized srt file, so what would I be syncing here?
I haven’t tried this command, but I believe the use case is as follows:
• Open audio/video file with —supposedly— synchronized file
• After a few seconds, I realize the subtitles appear before/after the dialogues
• I immediately close the multimedia player, and open the Terminal
• I execute the “subsync” command which does who knows what
• Open the SRT and discover that the subtitles are now in the correct timestamps
• ???
• Profit
Re: Show HN: Automatically synchronize subtitles with video
#17Sorry for the dumb question, but what exactly does this do? `subsync reference.srt -i unsynchronized.srt -o synchronized.srt` I mean, I already have a synchronized srt file, so what would I be syncing here?
It's quite common for different people to create their own subtitles for videos, and for all of these different subtitle versions be available for download at various subtitle sites on the internet.
If you've already synchronized one of these from the video itself (by using the voice detection algorithm described in the Readme, or maybe even by hand), it looks like you can then synchronize the rest using the already synchronized subtitle file. It's probably faster.
Re: Show HN: Automatically synchronize subtitles with video
#18This is cool. I am constantly impressed by ffmpeg and it capabilities. Last week I was able to make it act as a proxy for live streaming video that reduced the volume of ad-breaks by 50% automatically by listening for SCTE35 cue packets in the stream and adjusting a volume filter accordingly. My housemate has a reality TV addiction, and the ads were getting on my nerves. I just intended to see if it was possible, but…
A neat subtitle feature I found out mpv has, but no other video player: Hide those parts of the subtitle which are mainly for those with impaired hearing like '[loud noise]' etc, but keep the rest:
`mpv --sub-filter-sdh ...`
That logic could probably be extracted into a separate subtitle filtering tool.
Re: Show HN: Automatically synchronize subtitles with video
#19Sorry for the dumb question, but what exactly does this do? `subsync reference.srt -i unsynchronized.srt -o synchronized.srt` I mean, I already have a synchronized srt file, so what would I be syncing here?
Great question. The main use case I can think of is when reference.srt and unsynchronized.srt are in different languages, and you want to eventually merge them into a single dual-language subtitle file. EDIT: Oh, I should also mention that you don't need a reference.srt -- it can look at the video directly and use that as a reference.
Given it just processes audio, how long does processing one video file usually take?
Re: Show HN: Automatically synchronize subtitles with video
#20Sorry for the dumb question, but what exactly does this do? `subsync reference.srt -i unsynchronized.srt -o synchronized.srt` I mean, I already have a synchronized srt file, so what would I be syncing here?
Great question. The main use case I can think of is when reference.srt and unsynchronized.srt are in different languages, and you want to eventually merge them into a single dual-language subtitle file. EDIT: Oh, I should also mention that you don't need a reference.srt -- it can look at the video directly and use that as a reference.
Ohh now I got you. I believe README should be improved in this part then.
It reads:
====
Although it can usually work if all you have is the video file, it will be faster (and potentially more accurate) if you have a correctly synchronized "reference" srt file, in which case you can do the following:
subsync reference.srt -i unsynchronized.srt -o synchronized.srt
====
I believe you should explain that if you have a reference file in another language which is correctly synchronized with that video, you can use that file instead of the video, as its timestamps will serve as references when synchronizing the target .srt file.
Now this has raised a question, what if the reference file has a different block count? For example, in some languages (like Chinese or Japanese) we can say a lot with fewer characters than in English. So in Chinese a text will stay on the screen for a long time, whereas in English the corresponding text would be split into two or more blocks. Wouldn't that make synchronization less accurate?
BTW that's a cool project. Thanks for sharing!