概要
参考：
DASH Adaptive Streaming for HTML 5 Video | MDN
What is MPEG-DASH? / HLS vs. DASH | Cloudflare
Dynamic Adaptive Streaming over HTTP – Wikipedia
MPD ファイルを作成する (.mpd)
参考：
dash | FFmpeg Formats Documentation [Official]
Generate single MPEG-Dash segment with ffmpeg – Stack Overflow
Use FFmpeg to generate MPD files for MPEG-DASH adaptive streaming – Stack Overflow
How to create multi bit rate dash content using ffmpeg dash muxer – Stack Overflow