Multilanguage webVTT vod streams

Wowza Streaming Engine
,
1

As described here Wowza-Docs: “how-to-configure-closed-captioning-language-selection-for-video-on-demand-streaming#using-multi-language-caption-files” WSE might support multilanguage webVTT files. But I did not find the propper format for that. I assume a smil file must be created like this example Wowza-Docs: “how-to-stream-webvtt-subtitles-to-ios-for-closed-captioning#play-using-a-smil-file” with 2 or more languages as system-language and src pointing to one vtt file. Does somebody got that running? How must the vtt file be structured and the languages be separated if they are in one file.
Right now I record them in separated files (one per language). But as it looks like multiple files are not supported in the smil configuration. In this case only the first caption language is working, even if the lables for the others are visible in the player.

2

Hi Kay.

I believe for multi language VOD CC:

  • only TTML multi lang CC files are supported
  • you need to use a smil file to specify multiple languages
  • I believe (I may be wrong here), you need to set a property in the TimedText section of App.xml that specifies the comma separated list of possible language codes. This may not be needed if you use a smil file, but I seem to remember this needs set to make it work

Hopefully Wowza team can give more details and an example

3

Hi Scott, thanks for now. Lets see if the Wowza team responds. At least the “linked” examples in the docs should be more clear if only TTML is possible.

4

Thanks for raising this — we’ve also noticed similar behavior when working with multiple language WebVTT files for VOD.

It looks like the issue might come down to how the caption languages are being interpreted when captionLanguages is explicitly set vs using captionUndefinedLanguageId. We’ve seen cases where only one language shows up correctly depending on those settings, especially when using SMIL-based VOD setups.

If you’re still stuck, I’d actually recommend opening a support ticket with Wowza, as to take a closer look at your config and test setup. This might be something that needs deeper review or refinement in how caption languages are handled internally.

You can open a support ticket here:
:point_right: Open a Wowza Support Ticket | Wowza Media Systems

— Vijay