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DASH Closed Captioning from an MP4 with embedded TTML

I have mp4 files with embedded TTML data as a text track. When I upload these to my VOD application in Wowza Streaming Engine though, the MPD manifest for Dash is not including the text track.

Is this expected to work? If so, any pointers on what the track type has to be in the mp4 files, etc. for Wowza to find it and use it?



Hey Bill,

I have the same problem…

But as you can read here wowza doesn’t seem to support cc yet.




For now when using DASH you will have to use WebVTT sidecar files.

There is a fix for this feature that is still marked as Preview in the recent Engine update.

Fixed support for “sidecar” WebVTT caption files in on-demand MPEG-DASH streaming (preview feature)

Since this is marked as a “Preview” feature it is still not recommended for production delivery, but this is the option that is currently available.

Do note that active maintenance and support is required to access the latest update installers.



I have been also talking to a Wowza engineer through support ticket. The current recommendation is to use a WebVTT sidecar for closed captioning with DASH.

Unfortunately, the MP4 embedded TTML track is not supported yet, though they may add this in a future release.


how do you do it?

I still can’t get it to work :confused:

I’ve added ttml, srt and vtt to my SMIL, but getting no entry in the MPD file.