records from webcam when midi play button pressed and stops when stop button pressed

record-webcam-on-midi-play-button.sh

#!/bin/bash

device="/dev/v4l/by-id/usb-046d_HD_Pro_Webcam_C920_0AE6127F-video-index0"
takenum=1

aseqdump -p "MPKmini2" | \
	while IFS=" ," read src ev1 ev2 ch label1 data1 label2 data2 rest; do
		case "$ev1 $ev2 $data1" in
			"Note on 45" )

				killall ffmpeg
				if fuser -v $device > /dev/null 2>&1; then
				    printf '%s\n' "device in use"
				else
				    printf '%s\n' "device available"
				fi

				timestamp=`date +%Y%m%d-%H%M%S`;

				until pids=$(pidof ffmpeg)
				do
					ffmpeg -f v4l2 -s 1920x1080 -r 30 -input_format h264 -i $device -an -c:v copy -f avi - | tee "wc-$1 take-$takenum $timestamp.avi" | mpv - &
				sleep 0.2
				done

				((takenum++));
				;;

			"Note on 46" )
				killall ffmpeg;
				killall mpv;
				;;
		esac
	done