There is lot of mystery around CC608 usage under iOS.
Apple's UsingHLS offers to declare them in the manifest like this:
#EXT-X-MEDIA:TYPE=CLOSED-CAPTIONS,GROUP-ID="cc",NAME="CC1",LANGUAGE="en",DEFAULT=YES,AUTOSELECT=YES,INSTREAM-ID="CC1"
#EXT-X-MEDIA:TYPE=CLOSED-CAPTIONS,GROUP-ID="cc",NAME="CC2",LANGUAGE="sp",AUTOSELECT=YES,INSTREAM-ID="CC2"
#EXT-X-STREAM-INF:BANDWIDTH=1000000,SUBTITLES="subs",CLOSED-CAPTIONS="cc" x.m3u8
But Apple's official sample stream do include CC608 embedded into the MPEG, and still they didn't list them in their manifest!
On that sample stream, I can turn CC608 on using closedCaptionDisplayEnabled=YES, but this method does not allow selection of a specific language.
In Apple's dev forum I have found this question with a promising answer:
Are you still calling "player?.closedCaptionDisplayEnabled=true"?
There's no need to do that. If you author your HLS playlist properly with the appropriate language tags, the user can enable captions in the language of their choice, or disable them completely as well.
I was failing to find API in iOS which will allow me to:
- Read the list of available CC608 streams
- Activate CC for a specific language
Would appreciate your help with this!