dash stream with webvtt not show subtitle

Archived
1

I try to show subtitle in dash stream with webvtt, but failed.

I have set captionMode to “On” and can get available subtitle by availableSubtitleTracks field.

But, No matter I set by subtitleTrack field, or by remote controller(according to https://developer.roku.com/en-gb/docs/developer-program/media-playback/closed-caption.md), subtitle not shown.

Below is test stream I used from dash.js(http://reference.dashif.org/dash.js/latest/samples/captioning/multi-track-captions.html) :

https://dash.akamaized.net/akamai/test/caption_test/ElephantsDream/elephants_dream_480p_heaac5_1_https.mpd

Below are fields I got from player node:

availableSubtitleTracks: [{“Description”:“”,“Language”:“en”,“TrackName”:“dash/c~WEBVTT~en~main~”}]

currentSubtitleTrack: dash/c~WEBVTT~en~main~
globalCaptionMode: On

Is there anything I need to do except for setting captionMode and subtitleTrack?

Thanks,

Klaus

2

I tried that stream and just enabled captions using the remote while the stream was playing and I got captions. Are you getting captions on any videos in any channels?

3

Yes, I can see and control caption by merely changing streamFormat to hls and using url below.

https://devstreaming-cdn.apple.com/videos/streaming/examples/img_bipbop_adv_example_fmp4/master.m3u8 (from https://ottverse.com/free-hls-m3u8-test-urls/)

4

I know why this stream not show subtitle.

Subtitle content only exist on the front part of stream.

I have another question, If the subtitle content can’t get from server(for example, baseUrl in mpd is not right or resource on server is remove). Would it show any error message?