[FFmpeg-user] AES Enc with segmenter

[bra vo]

I would like to segment a live mpegts udp stream into hls and there are two
constraints:

1) Subtitles must be copied (dvbsub) to output; (If it can be converted to
webvtt it would be awesome)
2) The segments must be encrypted with AES128 and the playlist should
contains the URI to the key.

Well, the issue is that I can't achieve both at the same time. If I use the
ffmpeg hls muxer, it encrypt the chunks with AES but do not copy subtitles
to the output and throws an error: [webvtt @ 0x561100fa5700] Exactly one
WebVTT stream is needed.

Ok, then let's give the generic segmenter muxer a try. Good, it can copy
the subtitles to the hls output. Question is, how can I  encrypt the
segments on the fly and properly add te key URI to the manifest using this
generic segmenter? (Remember it's a live content)

Thanks!