I have Embedded 3GPP captions in an MP4 video and this is working perfectly in RTMP, HDS & HLS (both CEA-608 & WebVTT).
Now, I need adaptive VOD, so I have put two copies of this file in a SMIL (yes same bitrate for now, just testing).
Using the SMIL: Captions work for RTMP, HDS and HLS (CEA) - but not with WebVTT. I am no longer seeing the caption select menu in iOS.
I have tried using external TTML & SRT, instead of the embedded 3GPP, no change.
Conclusion : WebVTT not working on iOS when using a SMIL.
Please somebody prove me wrong ! with example