Closed captions / subtitles not displaying on Apple TV with fmp4 HLS

Hi,

We are testing HEVC video, which Apple requires fmp4 HLS. We have this all working on Apple TV 4K with the exception of closed captions / sub titles. We cannot get the sub titles to display - using ismc1 captions (from a ttml source) on Apple TV, though we can get it to display in Safari in some cases.


It seems as if this is either buggy or not sufficiently supported currently? Even Apple's advanced HEVC fmp4 sample stream does not display captions (from 607/708) nor the webvtt based sub titles


Apple Sample stream - from https://developer.apple.com/streaming/examples/


https://tungsten.aaplimg.com/VOD/bipbop_adv_example_hevc/master.m3u8


Has anyone had success with this?

Replies

no replies but if anyone is curious, we got it working with raw webvtt subtitles / captions. Couldnt get ISMC1 or embedded 608 captions working.

We just stumbled across the same issue. While we get webvtt displaying via subtitles, subtitles != closed caption.


Has anyone found a way to get tvOS to properly render cea608 captions out of HEVC segments?