I'm surprised I have never heard of the Helix streaming server before. However, a look at the supported formats makes me think matroska is not supported. This was the absolute goal of this project: stream in the matroska format. The reason is that most Anime and other subtitled videos are distributed in matroska, because it can mux SubStation Alpha subtitles. I wanted to be able to live stream Anime with my friends without anyone having to download it.