Recordings

Janus records to .mjr, its own container format. janus-pp-rec is compiled into this image to convert them.

Enabling

Recording is usually toggled at runtime by the application - for the videoroom plugin, via the enable_recording request - rather than being switched on in configuration. Set record and rec_dir in janus.plugin.videoroom.jcfg only if you want it always on.

Mount somewhere with real capacity:

volumes:
  - /srv/janus/recordings:/mnt/recordings

File layout

One file per media track, per participant:

videoroom-<room>-user-<userid>-<timestamp>-audio-0.mjr
videoroom-<room>-user-<userid>-<timestamp>-video-1.mjr

Converting

docker compose exec janus janus-pp-rec /mnt/recordings/<file>-audio-0.mjr /mnt/recordings/audio.opus
docker compose exec janus janus-pp-rec /mnt/recordings/<file>-video-1.mjr /mnt/recordings/video.webm

Then combine one participant's tracks:

ffmpeg -i video.webm -i audio.opus -c copy participant.webm

janus-pp-rec can also print a file's header without converting it, which is the quickest way to check a recording is intact:

docker compose exec janus janus-pp-rec --header /mnt/recordings/<file>.mjr

Checking a session immediately

ls -la /srv/janus/recordings/

Expect one file per track per participant, all non-empty. A zero-byte file means that track never started - worth catching while the participants are still there.