Transcode MP4 video to adaptive bitrate HLS.
Original motivation was for family videos on nextCloud, VOD from mobile devices.
hls-transcode <input MP4 videos>
Master HLS playlist for each video takes same name as video, with .m3u8 extension.
Bitrate-specific playlists and transcoded videos are in subdirs under .hls in the current directory,
named after each video file.
To edit the resolution and bitrates, edit the bitrate dictionary near the top of the script.