How to mux fragments already downloaded with N_m3u8DL-RE

[elektro]

I captured a livestream but N_m3u8DL-RE didn't mux the streams. They're in 2 folders (audio & video) with many small files. e.g.

_init.mp4
_init_dec.mp4
1072404251136_dec.m4s
1072404252288_dec.m4s
1072404253440_dec.m4s
1072404254592_dec.m4s

How to mux them in an MKV container?

[Obo]

Not sure if this works, but I'd try cat'ing the "*_dec.m4s" fragements into on big file, with _init_dec.mp4 the first fragment; i.e.

cat _init_dec.mp4 *_dec.m4s > video.mp4 (I don't know how this works on Windows, maybe "copy _init_dec.mp4 *_dec.m4s /b video.mp4" does the job)

and the same within the audio folder. If this works you will end up with a video.mp4 and audio.mp4 file that you can mux with MKVToolNix or ffmpeg.