Flowplayer will automatically load all subtitle tracks of your media, if any. If FlowplayerView was prepared with a valid FlowplayerMedia then a Flowplayer config will be fetched and all the subtitles that are included in
this config will be automatically added to your media.
In case your media doesn't contain any subtitles and you wish to add your own, create an ArrayList<Subtitle> and then pass this list as an argument to the ExternalMedia that will be used to prepare FlowplayerView.
Subtitle constructor takes two parameters, label of subtitle and url of subtitle.
val subtitlesList = ArrayList<Subtitle>("English", "https://link.to.a.subtitle.file")
val externalMedia = ExternalMedia("https://url.to.a.media.file", subtitles = subtitlesList)
Subtitle files must be in one of the following formats: WebVTT, TTML/SMPTE-TT, SubRip or SubStationAlpha (SSA/ASS).