ffmpeg bash script segment template

Question

I was trying to control ffmpeg file segment function through a bash script to cut a large movie file into smaller pieces.

I took a look at the documentation here but this doesn't really cover what I would like to do.

I'd like to mix the segment function with some of my own stuff from bash. Here is an example part of the script.

#!/bin/bash
DIR="/../../*"
OUT_DIR="/../../"
file_extension=""
filename=""
input_file=""
input_file_dir=""
output_file=""
working_directory=""
output_file_dir=""
part_count=0
for f in $DIR
do
    filename=$(basename "$f")
    input_file="$filename"
    filename=${filename::-4}
    file_extension=${f: -3}
    input_file_dir=$(dirname "$f")"/"
    part_count="$(printf "%03d" "$counter")"
    output_file="$filename"_"$part_count"."$file_extension
    //my file name generation takes place here
    output_file_dir="$OUT_DIR$filename"_"$part_count".mkv"
    let part_count=$part_count+1

    ffmpeg -i "$f" -c:v libx264 -crf 22 -map 0 -strict -2 -segment_time 600 -g 9 -sc_threshold 0 -force_key_frames "expr:gte(t,n_forced*9)" -f segment "$OUT_DIR"
done

The line above "$OUT_DIR" doesn't work and throws a cryptic error. If I remove "$OUT_DIR" and put anything, example "test.mkv" then the files get written out correctly but in the wrong location.

Can I do this with ffmpeg segment command and bash?

Answer 1

Okay so I figured it out and I rewrote the script from scratch.

#!/bin/bash
DIR="/../../../*" #directory where the movie files are located
OUT_DIR="/../../../../" #directory where the processed movie files will be exported
OUTPUT_FILE=""

file_duration_flat=0
file_duration_int=0
working_file_duration=0
default_chunk_size=600 #video length in seconds (10 minutes)
chunk_size=600 #video length in seconds (10 minutes)
video_pieces=0
video_pieces_hum_re=0
video_pieces_hum_re_cnt=0
counter=0
chunk_start_time=0
chunk_end_time=0
tt=10
end=10
iteration=0

#extract simple metadata from files
for f in $DIR
do
    echo $f
    file_duration_float=$(ffprobe -i "$f" -show_format -v quiet | sed -n 's/duration=//p')
    file_duration_int=$( echo "($file_duration_float+0.5)/1" | bc )
    working_file_duration_int=$file_duration_int
    working_file_duration=$(expr $file_duration_int - $chunk_size )
    echo $file_duration_int

    #---------------------------------------------
    # get the count of pieces to cut the file into
    #---------------------------------------------
    # echo $working_file_duration_int
    while [ "$working_file_duration_int" -ge "$chunk_size" ]
    do
        working_file_duration_int=$(($working_file_duration_int - chunk_size))
        video_pieces=$((video_pieces + 1 ))
        video_pieces_hum_re=$((video_pieces + 1 ))
        video_pieces_hum_re_cnt=$video_pieces_hum_re

        # echo "cut video into $video_pieces pieces"
        # echo "cut video into human readable $video_pieces_hum_re pieces"
        # echo "cut video human readable c $video_pieces_hum_re_cnt pieces"
    done
    #---------------------------------------------

    #---------------------------------------------
    # determine the start and end time of each clip
    #---------------------------------------------
    while [ $working_file_duration_int -gt -1 ]
    do
        filename=$(basename "$f")
        input_file="$filename"
        filename=${filename::-4}" "
        file_extension=${f: -3}
        input_file_dir=$(dirname "$f")"/"


        if [ $iteration -eq 0 ]
        then
            working_file_duration_int=$((file_duration_int - chunk_size))
            chunk_start_time=0
            chunk_end_time=$(($default_chunk_size))

            echo "iteration $iteration start: $chunk_start_time end: $chunk_end_time duration: $default_chunk_size video length left $working_file_duration_int"

            OUTPUT_FILE="$OUT_DIR$filename$iteration.mkv"
            $(ffmpeg -hide_banner -loglevel panic -i "$f" -ss $chunk_start_time -t $chunk_end_time [youre desired encoding] "$OUTPUT_FILE")
            iteration=$((iteration+1))
        fi
        if [ $working_file_duration_int -le $chunk_size ]
        then
            # echo "break early because time is $working_file_duration_int"
            chunk_size=$working_file_duration_int
            working_file_duration_int=$((working_file_duration_int - chunk_size))
            chunk_start_time=$(($chunk_start_time+$chunk_end_time))
            chunk_end_time=$(($chunk_size))

            # echo "early chunk size: $chunk_size iteration $iteration video length left $working_file_duration_int start: $chunk_start_time end: $chunk_end_time"
            echo "early chunk size: $chunk_size iteration $iteration start: $chunk_start_time end: $((chunk_start_time+chunk_end_time)) duration: $chunk_end_time video length left $working_file_duration_int "

            OUTPUT_FILE="$OUT_DIR$filename$iteration.mkv"
            $(ffmpeg -hide_banner -loglevel panic -i "$f" -ss $chunk_start_time -t $chunk_end_time [youre desired encoding] "$OUTPUT_FILE")
            iteration=0
            chunk_size=$default_chunk_size
            break
        else
            chunk_start_time=$(($chunk_start_time+$chunk_end_time))
            chunk_end_time=$(($chunk_size))
            working_file_duration_int=$((working_file_duration_int - chunk_size))
            echo "iteration $iteration start: $chunk_start_time end: $((chunk_start_time+chunk_end_time)) duration: $chunk_end_time video length left $working_file_duration_int "

            OUTPUT_FILE="$OUT_DIR$filename$iteration.mkv"
            $(ffmpeg -hide_banner -loglevel panic -i "$f" -ss $chunk_start_time -t $chunk_end_time [youre desired encoding] "$OUTPUT_FILE")
            iteration=$((iteration+1))
        fi
    done
done

This achieved what I needed it to do.