VTT writer and reader do not treat WebVTT cue ruby

[MtHunny]

Hello.

I am trying to convert between IMSC 1.1 and WebVTT including ruby.

For example, when I input the file ruby001.ttml from imsc-tests, it does not output the vtt file including ruby. The same goes for inputting a vtt file including ruby. Is there any plan for ttconv to support this?

Thanks

[palemieux]

As I recall the feature was deferred until ruby annotations were reliably supported by WebVTT players (@andreastai might recall differentely).

What is the level of support for ruby annotations in WebVTT players today?

[MtHunny]

Thank you.

I have tried the following VTTs: Chrome (and Edge), Firefox and Safari can render ruby.

WEBVTT

1
00:00:00.000 --> 00:00:01.000
<ruby>利用許諾<rt>ライセンス</rt></ruby>

If you have a renderer other than a browser that you often use, please let me know.

[palemieux]

Ok. It looks like we should plan on adding this feature.

Do you have a catalog of files available for testing?

[MtHunny]

Unfortunately I do not have the files. However, in my opinion, it is already in imsc-tests and ttconv/src/test in the necessary files.

In my opinion, there is no ruby functionality possible only in WebVTT.

I think the only CSS that can be specified for ruby in WebVTT is ruby-position. In other words, I think only ruby in imsc-tests is applicable. (rubyAlign is not.) However, as far as I confirmed, Chrome (and Edge), Firefox and Safari cannot render ruby-position.

Another feature related to ruby is writing-mode. This can be tested, for example, with bidi_vertical_lr.vtt and bidi_vertical_rl-oneline.vtt. Unfortunately, only Safari can render vertical-mode, Chrome and Firefox cannot.

I hope I can show you the information you need. Thanks.