Modern Samsung TVs are able to play movie with subtitles from DLNA server, but subtitles require some non-standard extensions of DLNA protocol. What it means: using standard DLNA server you can watch movie, though without subtitles.
This patch adds some of Samsung proprietary extensions, just enough for subtitles to work.
What it does:
1. When listing a folder, append non-standard <sec:CaptionInfoEx> tag to each video item. This tag servers only as a hint for Samsung client to check for subtitle download URL using HTTP HEAD method.
2. Before playing movie, Samsung device issues HTTP HEAD request on video item. In FileRequestHandler::get_info method we look for subtitle file and return it's download URL in CaptionInfo.sec header.
3. The device retrieves subtitles from URL provided in CaptionInfo.sec header. This is handled thanks to existing blind request feature.