Record various H264 video clips with different settings

chkrec.sh

#!/bin/sh


die() {
	cat << EOF
usage: $(basename $0) secs [timezone]

   30m =  1800s   1h =  3600s   4h = 14400s   7h = 25200s
   90m =  5400s   2h =  7200s   5h = 18800s   8h = 28800s
  120m =  7200s   3h = 10800s   6h = 21600s   9h = 32400s
                                             10h = 36000s
EOF
	exit 1
}

random() {
	r=$(($(dd if=/dev/urandom bs=4 count=1 2>/dev/null | cksum | cut -d' ' -f1) % 32768))
	r=${r#-} # convert to absolute value
	echo $(($r % $1))
}

pick_sign() {
	case "$1" in
		0) echo -;;
		1) echo +;;
		*) die;;
	esac
}

pick_hour() {
	case "$1" in
		0) echo 00;;
		1) echo 01;;
		2) echo 02;;
		3) echo 03;;
		4) echo 04;;
		5) echo 05;;
		6) echo 06;;
		7) echo 07;;
		8) echo 08;;
		9) echo 09;;
		10) echo 10;;
		11) echo 11;;
		12) echo 12;;
		13) echo 13;;
		14) echo 14;;
		*) die;;
	esac
}

pick_min() {
	case "$1" in
		0) echo 00;;
		1) echo 15;;
		2) echo 30;;
		3) echo 45;;
		*) die;;
	esac
}

test -n "$1" || die

test -n "$2" && (while kill -0 $$
do
	tz=GMT$(pick_sign $(random 2))$(pick_hour $(random 15))$(pick_min $(random 4))
	sleep 360
	echo change timezone to $tz
	echo $tz > /etc/TZ
done) 2>/dev/null &

while read idx sz bps h264fps fps
do
	${DO} ./timelimit -q -s INT -t $1 ffmpeg \
		-v verbose -nostdin -y \
		-f video4linux2 -input_format h264 \
		-video_size $sz \
		-framerate $h264fps \
		-bitrate $bps \
		-i /dev/video0 \
		-f alsa -i capture \
		-acodec pcm_s16le \
		-vcodec copy \
		-af 'pan=mono\|c0=FL' \
		-map 0 -map 1 \
		-r $fps -f segment \
		-segment_time 720 \
		-reset_timestamps 1 \
		-segment_format avi \
		${idx}_%3d_%F_%T.avi
done << EOF
720p 1280x720 1500000 24 30
480p  854x480  500000 24 30
360p  640x360  400000 24 30
240p  426x240  300000 24 30
EOF