Split videofiles by size approximately.

splitter.sh

#!/bin/bash
#
# Split video in chunks with similar size (depends on bitrate, the best option CBR).
#
# require: ffmpeg
# usage: splitter.sh -s chunk_size[KB,MB,GB] [--processes N] file [file ...]
#
# arguments:
# chunk_size[KB,MB,GB]      chunk size in KB, MB, GB, or bytes by default
# [--processes N]           (optional) number of parallel ffmpeg processes
# file [file ...]           input files
#

procs_num=1
while [ -n "$1" ]; do
    case "$1" in
        -s) size_number=$(echo "$2" | tr -dc '0-9')
        units=$(echo "$2" | tr -d '0-9')
        case "$units" in
            KB) chunk_size=$(( $size_number * 1024 ));;
            MB) chunk_size=$(( $size_number * 1024 * 1024 ));;
            GB) chunk_size=$(( $size_number * 1024 * 1024 * 1024 ));;
            *) chunk_size=( $size_number );;
        esac
        shift ;;
        --processes) procs_num=$2
        shift ;;
        *) break ;;
    esac
    shift
done

commands=()
files=( "$@" )
for file in "${files[@]}"; do
    info=$(ffprobe -show_entries format=size,duration -hide_banner -of default=nw=1 -v 0 "$file")
    for str in $info; do
        key=$(echo $str | cut -f1 -d=)
        value=$(echo $str | cut -f2 -d=)
        case "$key" in
            duration) duration="$value";;
            size) size="$value";;
        esac
    done
    chunk_duration=$(bc -l <<< "$duration / $size * $chunk_size * 0.97" | cut -f1 -d.)
    if [ -z $chunk_duration ]; then    
        echo "Approximate chunk duration is less than 1 second. Increase size of the part."
        exit
    fi
    fname=$(basename "$file")
    directory=$(dirname "$file")
    ext="${fname##*.}"
    filename="${fname%.*}"
    output_file="$directory/$filename%02d.$ext"
    commands+=("ffmpeg -v 24 -hide_banner -i \\\"$file\\\" -c copy -f segment -segment_time $chunk_duration \\\"$output_file\\\"")
done
printf "%s\n" "${commands[@]}" | xargs -I CMD --max-procs=$procs_num bash -c CMD