New subtitle support

[ferishili]

This PR fixes #48

Description

In Opencast 15, captions (subtitles) are provided with different format as for their flavors: captions/delivery ... etc. and every other data including language code etc. is included in the tags.

Solution

• This patch covers the new subtitles format while it maintain the old ones.
• The get_caption function now cover attachments and media and for media also looks for old and new subtitles.

To TEST

• You would need to have Opencast 15.
• You would need to have auto generated captions as well as manually uploaded caption via block_opencast plugin (or any other way) in order to test all cases.
• Try to watch the event via this plugin or in filter plugin
• All captions must be accessible in the paella player!

[mwuttke]

Hello @ferishili,
I tested videos with subtitles created by amberscript in english & in german with in the mod plugin, embedded in a page and embedded in a book page. And I tested videos with subtitles created by whisper and by whipsercpp in english & in german with in the mod plugin, embedded in a page and in a book page. In all scenarios the subtitles where shown.
So the patch works for me. ;-)

We used for the test scenarios Opencast Version 15.3 and Moodle Version 4.1.9+.

[mwuttke]

@NinaHerrmann & @justusdieckmann, what do you think speaks against reviewing and releasing this PR?

[NinaHerrmann]

We do not have the capacity to review it.

[justusdieckmann]

Hey @ferishili,

thank you very much for the pull request!

If I understand correctly, in all cases where the strpos is checked, the search-string should be at the start of the full string, right? So maybe strpos(...) === 0 would be better in those cases. Also, instead of str_replace('prefix', '', $tag), maybe you could use substr($tag, strlen('prefix')), because that will also work correctly in the (very unlikely) case, that 'prefix' is contained later in the string again.

Do you have any pointers to workflows or documentation regarding how to best setup the automatic captions to have an video to test with? I have found a talk about it, and the ts-api repo, but no instructions how to integrate it in opencast.

Thank you!
Justus

[ferishili]

Hi @justusdieckmann,
The changes are applied.

Unfortunately, I have very little knowledge about automatic captions, but I would guess these docs could help!

https://docs.opencast.org/r/15.x/admin/#configuration/transcription.configuration/whisper/
https://docs.opencast.org/r/15.x/admin/#configuration/transcription.configuration/vosk/