fax-a-video

fax-a-video.sh

#!/bin/bash

# Script to create one or more images of a number n of equally spaced frames of video.
# Adding a caption with a prefix and counting number.

# this version	20221219
# init		20210321

# Licence: 	WTFPL

# see https://github.com/Wikinaut/utils/wiki#How_to_extract_every_nth_frame
# how to convert a video to a sequence of its frames as single images
# ffmpeg -i in.mp4 %04d.jpg

# How to extract every n-th frame, every keyframe, or frames every n-th second:
# ffmpeg -i in.mp4 -vf fps=1/5 %04d.jpg

red="\e[1;31m"
yellow="\e[1;33m"
nocol="\e[0m"

if [ $# -lt 5 ] ; then

 echo "Add a prefix text and numbers to images of a video and collage-arrange them"
 echo
 echo "Usage:"
 echo "fax-a-video <videofile> <pick-n-frames> <ColumnxRow (tiles)> <pointsize> <prefix>"
 echo

 exit

fi

nframes=$2
tiles=$3
pointsize=$4
prefix=$5

# get number of frames
nbframes=$(ffprobe -select_streams v -show_streams "$1" 2>/dev/null | grep nb_frames | sed -e 's/nb_frames=//')

# https://www.reddit.com/r/ffmpeg/comments/feort1/how_to_generate_video_thumbnails_with_evenly/
duration=$(ffprobe -v 0 -show_entries format=duration -of default=nw=1:nk=1 "$1")

echo -e "$red$1: $nbframes ($duration seconds).$nocol"

# ffmpeg -i "$1" \
# 	-vsync vfr \
#	-vf "select=(isnan(prev_selected_t)*gte(t\,$duration/$2))+gte(t-prev_selected_t\,$duration/13),scale=160:120:force_original_aspect_ratio=decrease,tile=4x3" \
#	"${1%.*}-%05d.jpg"


ffmpeg -i "$1" \
	-vsync vfr \
	-vf "select=(isnan(prev_selected_t)*gte(t\,$duration/($nframes+1)))+gte(t-prev_selected_t\,$duration/($nframes+1))" \
	"${1%.*}-%05d.jpg"

number=1

for f in "${1%.*}"-*.jpg; do
   convert "$f" -gravity south -font Hack-Regular -pointsize $pointsize -undercolor white -fill black -annotate 0 "${prefix}${number}" miff:-
   ((number++))
done | montage -geometry 'x600>+12+12' -tile $tiles - "${1%.*}.collage.jpg"

# cleaning up
rm "${1%.*}"-*.jpg