Greasy Fork

(Feature request) Can you add the option to download IMSC 1.1 subtitles? Netflix currently uses IMSC 1.1 for subtitles (plus xHE-AAC for audio) on web browser playback. Subtitles in Arabic, Chinese, Japanese, Korean, Thai and Vietnamese are only available as VTT and IMSC 1.1, so when you set it to "prefer DFXP/XML" it fails and gets the VTT versions for those languages instead. In the case of Japanese, only the IMSC subtitles have support for ruby text/furigana.

The profile is "imsc1.1". Subtitle Edit uses the .xml extension for it.
The SimpleSDH format exists ("simplesdh" profile) in case you want to add that too.

Thank you.

That's not hard to add (thanks for providing the profile name, I don't have Netflix sub), but the question is how to implement it. Should I let people decide exactly which format to use? Or just change "prefer DFXP/XML" to "prefer IMSC/DFXP/XML" and call it a day?

Right now the priority of formats is VTT/DFXP/SimpleSDH when you select "prefer WebVTT" and DFXP/SimpleSDH/VTT when you select "prefer DFXP/XML".

So if I make it "prefer IMSC/DFXP/XML" then you probably won't even see DFXP or SimpleSDH formats at all - unless subs in IMSC format are not added to all movies/series.

What do you think? Are there any benefits of one of these formats over another? They are all XML formats (except for WebVTT one) and all of them have to be converted anyway.

Okay, somehow I missed that SimpleSDH is already there.

IMSC 1.1 (or IMSC 1.1 Netflix Text Profile) is a profile of TTML2. It supports ruby text/furigana while the other formats don't. The general IMSC 1.1 profile is only missing a few timing-related and pixel aspect ratio features from TTML1 which I think Netflix doesn't use. The Netflix IMSC 1.1 profile is more restricted but I don't think these features were used in the DFXP subs either.
https://www.w3.org/TR/ttml-imsc1.1/
https://partnerhelp.netflixstudios.com/hc/en-us/articles/360053755033-Netflix-IMSC-1-1-Text-Profile

DFXP is a profile of the older TTML1 format.

SimpleSDH is described by a 2016 Netflix article as "Supports only text and timing information. This profile doesn’t support any positional information and is expected to be consumed by the most resource-limited devices" so I think it should have a lower priority than WebVTT, which has more features.
https://netflixtechblog.com/a-scalable-system-for-ingestion-and-delivery-of-timed-text-6f4287a8a600

"VTT and IMSC/DFXP/VTT/XML" (fallbacks, SimpleSDH/XML only if everything else fails) sounds right to me. I don't think other "specific format" options (only IMSC, DFXP or XML) would be useful.

Thank you for the detailed info! Try 4.2.7, I hope I didn't make any mistake, since I can't test it. I didn't make "prefer IMSC/DFXP/XML" default. I may do it in the future though.