credits: endrift and MarioMasta64, slightly modified by me

readme.md

this script truncates videos to mp4 files of 29 second clips and fixes audio compatibility for Twitter's janky fleets

fleeter.sh

#!/bin/sh

if [ $# -eq 0 ]; then
    echo "Usage: fleeter FILE\n"
    exit 1
fi

VIDEO=$1

LEN=$(ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 "$VIDEO")
CHUNKSIZE=29
EPSILON=0.1
CHUNKS=$(echo "scale=0;($LEN + $CHUNKSIZE - $EPSILON) / $CHUNKSIZE" | bc)
for C in $(seq 0 $(($CHUNKS-1))); do
    # add echo to the front to see output as test
    ffmpeg -ss $(printf "%02i" $(( $C * $CHUNKSIZE / 3600 ))):$(printf "%02i" $(( $C * $CHUNKSIZE / 60 % 60 ))):$(printf "%02i" $(( $C * $CHUNKSIZE % 60))) -i "$VIDEO" -t $CHUNKSIZE -sn -c:a aac -b:a 256k -pix_fmt yuv420p -c:v libx264 -crf 14 $(($C+1)).mp4
done