Add a timer or other text display to a video using FFMPEG

add_timer.sh

#!/bin/bash

# From: https://discuss.kde.org/t/date-time-overlay-in-timelapse-video/2880/5
# Monospaced font from here: https://www.1001fonts.com/download/digital-7.zip

INPUT_FILE="video.mp4"
TOTAL_DURATION=30  # Total duration in seconds
FPS=30
FONT_FILENAME="./digital-7/digital-7 (mono).ttf"
FONT_SIZE=72
FONT_COLOR="white"
OUTPUT_BITRATE=800k
ffmpeg -an -y -i ${INPUT_FILE} -vf "drawtext=fontfile=${FONT_FILENAME}:
fontsize=${FONT_SIZE}:
fontcolor=${FONT_COLOR}:
x=w-tw-50:
y=h-th-50:
text='%{eif\:trunc(n/${FPS}*${TOTAL_DURATION}/(${FPS}*60*60))\:d\:02}\:%{eif\:trunc(mod(n/${FPS}*${TOTAL_DURATION}/(${FPS}*60),60))\:d\:02}\:%{eif\:trunc(mod(n/${FPS}*${TOTAL_DURATION}/${FPS},60))\:d\:02}'" \
-vcodec libx264 \
-b ${OUTPUT_BITRATE} \
-f mp4 output.mp4