subsync
Dev tools
subtitle alignment tool
SHOW HN2019
583points
124comments
#23of 2,195 in 2019
Top 2%of 2019 by points
How HN took it
CuriousMostly questions and neutral comments
9 positive, 35 neutral or asking, 0 mixed, 6 critical, out of 50 comments about the project. Thread score +0.03.
Execution: 2 for, 4 againstIdea: 5 for, 0 againstPerformance: 0 for, 2 againstDocs: 1 for, 0 against
The thread, comment by comment
Each row is a top-level comment and its replies, in HN's order. Select a cell to open that comment on HN.
positive neutral or mixed critical about another commenter or something else the maker
What HN said
What people liked
Clever use of FFT to make alignment O(n log n)
From 2 comments
From the README: "[...] the naive O(n^2) strategy for scoring all alignments is unacceptable. Instead, we use the fact that "scoring all alignments" is a convolution operation…
anyfoo on HNThis is quite amazing. The code quality overall looks pretty good too. Pleasantly surprised to see it in Python. Was dreading complex C++ code. Thanks for sharing. The code will…
sidcool on HN
Works well and is fast for long videos
From 1 comment
It's actually fairly annoying for subtitles, but it's useful for getting videos in unfamiliar languages to the right ballpark. Afterwards, my go-to so far has been to just…
smacke on HN
Objections
Only corrects constant drift, not varying drift
From 3 comments
Actually, it unfortunately doesn't work if the drift gets worse over time -- so far, it only works with constant drift. Maybe fixing constant 1st derivative drift is the next step!
smacke on HNMy guess is that your subtitles don't have a "fixed drift". Unfortunately, this project only works for constant drift at the moment -- dynamic subtitle drift is a harder problem…
smacke on HNYou are most welcome, although unfortunately it looks like this project doesn't support your use case yet. Right now it can only correct "constant drift", although I'll…
smacke on HN
Errors of around 1 second are noticeable
From 2 comments
> I have yet to find a case where the automatic synchronization has been off by more than ~1 second That's actually quite bad synchronization error for A-V; maybe it's less…
loeg on HN> I have yet to find a case where the automatic synchronization has been off by more than ~1 second. 1 second is in the 0 - 1000ms which is still a lot of room for manual…
kowdermeister on HN
Would not pass broadcaster QC tolerances
From 1 comment
This is an area I am actively looking into at the moment for my employer. It's an interesting project, and I am excited to see work in this domain. Note that this will not pass…
draz on HN
Requests
Handle varying drift and frame-rate differences
From 3 comments
I'm still waiting for the day there is an automatic synchronizer for the video and audio tracks in VLC. It's so frustrating trying to find the right offset when they get out of…
ummonk on HNThis blows my mind (like everyone else's here)! While playing digital copies of somewhat older movies (before BluRay rips came into vogue), a problem which surfaces frequently is…
kumarharsh on HNAwesome! According to the description of the internals this only works with offsets and doesn't adjust the subtitle's playback speed. I think playback speed variations are not…
dearrifling on HN
Support for detecting extra scenes in director's cuts
From 1 comment
An even harder and cooler problem to solve would be finding extra scenes. Sometimes subtitle or movie have slightly different "cut" (e.g. directors cut) and there are some extra…
kozikow on HN
Clearer README on the reference.srt usage
From 2 comments
"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…
acqq on HNSorry 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…
kojackst on HN
Questions
How does the reference subtitle file work
From 2 comments
"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…
acqq on HNSorry 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…
kojackst on HN
Alternatives named
aligner (kaegi)
From 1 comment
I recently ran across a similar tool for aligning subtitles based on a reference subtitle file called aligner: https://github.com/kaegi/aligner It seemed to work pretty well in…
boolemancer on HN
subtitle-synchronization (AlbertoSabater)
From 1 comment
Nice! Have you seen this similar project? If not sure if there are any ideas to be borrowed, but it sounds like it achieved excellent accuracy:…
symstym on HN
forced alignment tools
From 1 comment
This 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:…
lern_too_spel on HN
Subtitle Workshop
From 1 comment
I see this will only shift the timings some offset. But many times it isn't enough e.g. if the video source is NTSC and the subtitle were meant for PAL. In this scenario I use…
hobbes78 on HN