moving bar testcard generator for synchronization testing based on timestamps

sync_bar_gen.sh

#!/bin/bash
fps=25
delay=2

width=640
height=360
bar_width=20
bar_height=$((height / 2))
bar_speed=4

streams=(
##ACTIVE
"srt://stream1:1234"
"srt://stream1:1234"
"srt://stream1:1234"
##TEST
#"srt://some_unused_stream"
#"srt://some_other_unused_stream"
)

colors=(
"white"
"yellow"
"cyan"
"green"
"magenta"
"red"
"blue"
)

font="/usr/share/fonts/truetype/noto/NotoMono-Regular.ttf"
fontsize=24
text1="\'TELLYO TS SYNC"
text2="%{eif\:mod(n\,1000)\:d:3}\'"
#%{localtime\:%T}\'"

on_die ()
{
    # kill all children
    pkill -KILL -P $$
}

trap 'on_die' TERM

for i in "${!streams[@]}"
do
    frequency=$(awk "BEGIN { printf \"%.2f\", 220 * (2 ^ (1/3)) ^ $i }")
    j=$((i+1))
    text="$text1 $j $text2 +$((i*delay))s"
    echo "Running $j to ${streams[$i]}"

    /apps/ffmpeg/bin/ffmpeg -loglevel 0 -hide_banner -re -f lavfi -i color=s=${width}x${height}:rate=$fps \
        -f lavfi -i sine=$frequency:r=48000 \
       -filter_complex "color=${colors[$i % 7]}:size=${bar_width}x${bar_height}:d=1[c]; \
                        [0:v][c]overlay=x='mod(n*${bar_speed},${width})',drawtext=fontfile=${font}:fontsize=${fontsize}:line_spacing=15:box=1:boxcolor=black@0.75:boxborderw=5:fontcolor=white:x=(w-text_w)/2:y=((40)/2):text=${text}" \
        -c:v h264 -tune:v zerolatency -profile:v baseline -pix_fmt yuv420p -preset:v ultrafast -force_key_frames 'expr:gte(t,n_forced*2)' -sc_threshold 0 -crf 22 -ac 2 -c:a aac -map_metadata -1 -f mpegts ${streams[$i % 7]} &

    sleep $delay
done

wait