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Show HN: Automatically synchronize subtitles with video

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Re: Show HN: Automatically synchronize subtitles with video

#111

Post by oasisbob »

kumarharsh wrote: post #59

Completely tangential question to this awesome discussion: who even writes subtitles? It feels like a thankless job to write subtitles for rips of movies and TV shows old and new. I get that maybe they source original from, say, Netflix, but .set files existed long before Netflix, and for lots of movies not on Netflix. Writing all those tags for hearing impaired seems like a lot of work, which anyone other than the f…

I'm equally amazed by the effort that goes into foreign dubbing. Staying in Chennai, India and channel surfing, Sky TV had dozens of US channels (TLC, Discovery channel, etc) which not only had English/Hindi/Tamil subtitles - but foreign language dubs too!

Not just movies, but full overdubbing for 20-episode season disposable reality TV shows. Think, "Storage Wars" etc. Spent over an hour channel surfing and flipping languages.

I would /love/ to know how they take the original subtitle tracks and translate/dub them efficiently.

Re: Show HN: Automatically synchronize subtitles with video

#112

Post by FranOntanaya »

kumarharsh wrote: post #59

Completely tangential question to this awesome discussion: who even writes subtitles? It feels like a thankless job to write subtitles for rips of movies and TV shows old and new. I get that maybe they source original from, say, Netflix, but .set files existed long before Netflix, and for lots of movies not on Netflix. Writing all those tags for hearing impaired seems like a lot of work, which anyone other than the f…

TED Talks for example has a community of volunteer subtitlers that get credit for their work. A lot of them move on from there to professional captioning.

Re: Show HN: Automatically synchronize subtitles with video

#113

Post by xpil »

kumarharsh wrote: post #59

Completely tangential question to this awesome discussion: who even writes subtitles? It feels like a thankless job to write subtitles for rips of movies and TV shows old and new. I get that maybe they source original from, say, Netflix, but .set files existed long before Netflix, and for lots of movies not on Netflix. Writing all those tags for hearing impaired seems like a lot of work, which anyone other than the f…

A friend of mine does it as a hobby.

Re: Show HN: Automatically synchronize subtitles with video

#114

Post by zimpenfish »

amelius wrote: post #107
zimpenfish wrote: post #105

Earlier quoted context omitted.

Since I already had it open (for unrelated reasons), this might be relevant. https://en.wikipedia.org/wiki/Smith%E2%80%93Waterman_algorit... > The Smith–Waterman algorithm performs local sequence alignment; that is, for determining similar regions between two strings of nucleic acid sequences or protein sequences.

But also: > The Smith–Waterman algorithm is fairly demanding of time: To align two sequences of lengths m and n, O(mn) time is required.

Thankfully I'm only working with short sequences but yeah, I guess that might be a problem.

Re: Show HN: Automatically synchronize subtitles with video

#115

Post by amyjess »

kumarharsh wrote: post #59

Completely tangential question to this awesome discussion: who even writes subtitles? It feels like a thankless job to write subtitles for rips of movies and TV shows old and new. I get that maybe they source original from, say, Netflix, but .set files existed long before Netflix, and for lots of movies not on Netflix. Writing all those tags for hearing impaired seems like a lot of work, which anyone other than the f…

> who even writes subtitles?

I do, as a hobby. Typesetting in particular is one of the most rewarding things I've ever done. There are few things as satisfying me as being able to set a sign so that it looks like it's part of the video.

If you're curious, there's a tool out there called Aegisub. Pretty much every fansubber uses it, and it can handle most parts of the process: timing, typesetting, TL/editing, and it shows you a preview of what it looks like muxed with the video (though you do need a separate tool to actually generate muxed MKV files).

> Both are in English, so I don't see why they can't just transcribe what's being said. Instead, for dialogues such as "The greatest trick the Devil ever pulled was convincing the world he didn't exist.", the subtitle is written as "The devil tricked the world into thinking he didn't exist."

You have entered the wonderful world of Hong Kong bootlegs, which are usually just called "HKs". The people who work on these just plain don't care. They translate the movie into Chinese, and then for whatever other language they release subtitles in, they just Google Translate their Chinese subs into that language, even if it's the movie's original language.

Fansubbers hate them, and if the show or movie in question was never officially released in English, there are some groups who will clean up these subtitles to make them more presentable and fixing the godawful grammatical errors (this is called "scrubbing"). Of course, you're still left with a shitty base TL, but it's at least better than the HKs-as-is, so these scrubs are always just a stopgap until somebody can do a full TL. And there are some groups who will subtitle a series from scratch just to spite the HKs.

The only thing good about these subs is that they tend to turn into memes. I'd recommend looking up the HKs of Revenge of the Sith, which ended up becoming an impressive stockpile of memes, most famously being the origin of "Do not want!". For memes that came out of shows I actually watch, I'd recommend googling phrases like "Don't molest the lawyer" and "Gao Main Bastard".

Re: Show HN: Automatically synchronize subtitles with video

#116

Post by [deleted] »

kumarharsh wrote: post #59

Completely tangential question to this awesome discussion: who even writes subtitles? It feels like a thankless job to write subtitles for rips of movies and TV shows old and new. I get that maybe they source original from, say, Netflix, but .set files existed long before Netflix, and for lots of movies not on Netflix. Writing all those tags for hearing impaired seems like a lot of work, which anyone other than the f…

[deleted]

Re: Show HN: Automatically synchronize subtitles with video

#117

Post by _fbpt »

aabeshou wrote: post #55
hosay123 wrote: post #48

Earlier quoted context omitted.

I thought I understood FFT, but totally not getting the relationship to this problem. Someone ELI5 please? :)

ELI5: You can turn this problem into finding the best "convolution index", and fourier transforms make computing convolutions cheaper. ELIUndergrad: (note that \* means multiplication, there doesnt seem to be a way to escape an asterisk) Lets start by seeing how this is a convolution. We have the videoSpeech sequence, and the subtitle sequence - each is a vector, indexed by time, of 0's and 1's indicating whether the…

I've beem working on a similar algorithm.

I'm writing a program which takes multiple channels of near-periodic audio wav files, and outputs a phase-stable oscilloscope video. This is done by FFT-correlating (a buffer of recent oscilloscope plots) with (the audio signal) (with quite a bit of added complexity for better results). Incidentally I'm also using Python/Numpy/ffmpeg.

It's most useful for "complex" chiptune like FM/SNES/tracker/MIDI music, which are easy to split into monophonic single-note channels. https://github.com/corrscope/corrscope Should I submit this separately (Show HN)?

Re: Show HN: Automatically synchronize subtitles with video

#118

Post by Guillaume86 »

apexalpha wrote: post #95

Please tell me someone that works at Plex is reading this thread. I know it might seem a bit distant for Americans but this HUGE!

A Kodi plugin might be a more realistic target, subtitles handling in Kodi is pretty great in my experience, especially compared to Plex (download while playing, sources addons, offset adjustement).

Re: Show HN: Automatically synchronize subtitles with video

#119

Post by MagnumOpus »

oasisbob wrote: post #111
kumarharsh wrote: post #59

Completely tangential question to this awesome discussion: who even writes subtitles? It feels like a thankless job to write subtitles for rips of movies and TV shows old and new. I get that maybe they source original from, say, Netflix, but .set files existed long before Netflix, and for lots of movies not on Netflix. Writing all those tags for hearing impaired seems like a lot of work, which anyone other than the f…

I'm equally amazed by the effort that goes into foreign dubbing. Staying in Chennai, India and channel surfing, Sky TV had dozens of US channels (TLC, Discovery channel, etc) which not only had English/Hindi/Tamil subtitles - but foreign language dubs too! Not just movies, but full overdubbing for 20-episode season disposable reality TV shows. Think, "Storage Wars" etc. Spent over an hour channel surfing and flipping…

Dubbing is a major industry in many non-English-speaking countries (Germany, France, Spain, Italy etc), employing more than half of voice actors -- so it's generally not some DIY cottage industry, but professional audio engineers and voice actors. They don't just use subtitles, they use the original video/audio to lip-sync as well as possible.

Wikipedia has some more detail: https://en.wikipedia.org/wiki/Dubbing_(filmmaking)#Methods

Re: Show HN: Automatically synchronize subtitles with video

#120

Post by smacke »

kojackst wrote: post #20
smacke wrote: post #13

Earlier quoted context omitted.

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 r…

Sorry, I forgot to answer your last question. It turns out that, because of how the algorithm works, the number of blocks shouldn't matter. Since it is discretizing time windows in 10ms increments, the granularity of the "effective blocks" is small enough that putting two separate large blocks on the screen, each for a shorter period of time, is roughly equivalent to putting a single large block on the screen for twice as long (for synchronization purposes, that is).
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