Script mixing Janus .mjr video files (videocall recordings)

merge_video.sh

#!/bin/bash

JANUS_BIN=/usr/bin/janus-pp-rec
FFMPEG_BIN=/usr/bin/ffmpeg


file1=$1
file2=$2
out1=${file1%.mjr}.webm
out2=${file2%.mjr}.webm

if [ -z "$3" ]
then
  out3=OUTPUT.webm
else
  out3=$3
fi

start1=`$JANUS_BIN --extended-json $file1 | jq ".u"`
start2=`$JANUS_BIN --extended-json $file2 | jq ".u"`
delay=$((($start1-$start2)/1000))

if [ $delay -lt 0 ]
then
  delay1=0
  delay2=${delay#-}
else
  delay1=$delay
  delay2=0
fi

$JANUS_BIN $file1 $out1
$JANUS_BIN $file2 $out2

$FFMPEG_BIN -i $out1 -i $out2  -filter_complex "[0:v]format=yuv420p, scale=640:360:force_original_aspect_ratio=increase,\
                                                crop=640:360,setsar=1,setpts=PTS-STARTPTS,tpad=start_duration=${delay1}ms:start_mode=add:color=black[l]; \
                                                [1:v]format=yuv420p, scale=640:360:force_original_aspect_ratio=increase,\
                                                crop=640:360,setsar=1,setpts=PTS-STARTPTS,tpad=start_duration=${delay2}ms:start_mode=add:color=black[r]; \
                                                [l][r]xstack=inputs=2:fill=black:layout=0_0|w0_0, pad=1280:720:-1:-1[stacked]" -map [stacked] -preset superfast $out3
rm -f $out1 $out2