SMPTE-TT CODEC not recognized in HLS master playlist

[jparekh-tivo]

Issue description

​
SMPTE-TT CODEC not recognized in HLS master playlist
​​
The DASH manifest specifies the SMPTE-TT captions in the codecs in the manifest (from W3C TTML Profiles for Internet Media Subtitles and Captions 1.1.
​
Apple describes IMSC1 in MP4 in RFC-8216 Section 3.6
​
They use the SHOULD and MAY mealy words to imply the codec to use for it in the Authoring Guidelines
​
The origin server vendors put all this together and implement a playlist that expects EXT-X-MEDIA:TYPE=SUBTITLES to work like this
​

Proposed Solution

Pull request issued 7184. The solution was to modify the HlsPlaylistParser to look for codecs in references to the subtitle media.
​

Reproduction steps

Test case shows both paths (exiting default to VTT) and IMSC codec.
​

Link to test content

​
Sorry, we don't have a sample that is not live. We can get this if absolutely needed
​

A full bug report captured from the device

N/A
​

Version of ExoPlayer being used

2.11.4
​

Device(s) and version(s) of Android being used

N/A test case.