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Comment by virtue3 | Hacker News Reader

I worked at crunchyroll.

Keeping the "hard subs" content is a lot of videos as the subtitles were encoded into the video stream.

This makes CDNs and other systems more difficult to utilize because we have a ton of video streams with just caption changes as opposed to just the Japanese audio source + caption files.

It's one of those things that doesn't seem that problematic till you include all the video_qualities to support streaming bandwith. So you also get a #hardSubLanguages * #videoQualities

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Obviously you probably thought about it but what about rendering the subtitles on top of the video stream? Was there a reason it was not possible (e.g DRMs?)

This kind of softsubbing is what Crunchyroll primarily does, but it has hardsubbed encodes for devices that cannot do softsubbed rendering of the ASS subtitles that Crunchyroll uses. I go over some ways in how they could do away with these hardsubbed variants in the article without any notable loss in primary experience quality.

They could borrow a trick from Netflix mentioned elsewhere in this thread: https://netflixsubs.app/docs/netflix/features/imgsub

I’m pretty sure it’s not too hard to implement an ASS → PNG renderer (especially considering vibe coding is now a thing). Then, just need to split out subs that can be actual text somehow from the ones that have to be overlays.

Apart from that... surely they could at least keep ASS subs for the players that support it, and serve “fallback” subs for low-end devices?

ASS can have frame-by-frame animation IIRC, so a stream of PNGs could end up being quite high bitrate with high complexity files

It can, but that doesn't mean they use that functionality.

It is harder than you think and will break on many more devices than you think.

So you make the business decision to stop supporting weird devices that can't do the job right? Why on earth does a cartoon streaming site need provably-correct subtitle support for devices that clearly suck?

Because the owners of those devices are paying them.

I’ve mentioned it elsewhere, but... why not keep proper ASS subs and fallback subs for those devices?

If you hardsub the video, then you need to have a full copy of the video for every language. That's the opposite of what people want. They want a single textless video source that can then accommodate any internationalization.

The article claims that you can slice up the video and only use language-specific hardsubs for parts that need it. I'd be interested if there are technical reasons that can't be done.

To be more specific, basically all online streaming today is based around the concept of segmented video (where the video is already split into regular X-second chunks). If you only hardsubbed the typesetting while keeping the dialogue softsubbed (which could then be offered in a simpler subtitle format where necessary), you would only need to have multiple copies of the segments that actually feature typesetting. Then you would just construct multiple playlists that use the correct segment variants, and you could make this work basically everywhere.

You can also use the same kind of segment-based playlist approach on Blu-ray if you wanted to, though theoretically you should be able to use the Blu-ray Picture-in-Picture feature to store the typesetting in a separate partially transparent video stream entirely that is then overlaid on top of the clean video during playback.

Technically it's possible.

We did do inlaid server-side ads that way for a while.

IT just takes an excessive amount of work.

The real solution is just the full support of ASS/TTML/VTT subtitles on all platforms. Usually smart devices are kind of only partially supported.

For instance - casting to a chromecast fallsback to SRT.

It's incredibly fragile at the CDN level if deployed at scale for a start.

You'd see playback issues go up by 1000%.

In the nicest possible way, it is pretty clear that this article was written by somebody who has only ever looked at video distribution as a hobbyist and not deploying it at scale to paying customers who quite reasonably get very upset at things not working reliably.

What would be the problems? When I’ve looked into streaming video before (for normal, non ripping reasons), I’ve noticed that most are already playlists of segments. You’d just need to store the segments that are different between versions, which should be better than keeping full separate versions which is what they apparently do currently.

This is just an excuse. There needs to be a hard english sub and then keep other languages can be single video with different text file. Deleting 80% good things only to keep other 20% happy should not be an excuse.

Only english is the most popular and just keep it. Most of the good hard subs are made for english and that is what people want.

That is exactly what I thought and I am not even a native English speaker. My English is infinitely better than my Japanese though, so if I cared about anime I’d much rather watch a good English version rather than a bad German one

Guess how well supported soft subs are on smartTVs etc? :)

It's really tough when you need to scale these things across 20 platforms.

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