Using FFmpeg to split multimedia file into parts based on audio volume level

splitaudio.sh

#!/bin/bash

# Modified from original to encode as mp3, renamed to 'splitaudio', and made the usage text more substantial

IN=$1
OUT=$2

true ${SD_PARAMS:="-55dB:d=0.3"};
true ${MIN_FRAGMENT_DURATION:="20"};
export MIN_FRAGMENT_DURATION

if [ -z "$OUT" ]; then
    echo "Usage: splitaudio <input_file> <output_template>"
    echo ""
    echo "Depends on FFmpeg, Bash, Awk, Perl 5. Not tested on Mac or Windows."
    echo ""
    echo "Arguments:"
    echo "  <input_file>                Media file with silences, to split"
    echo "  <output_template>           A printf-style string such as output-%03d.mp3 which increments for each output file"
    echo ""
    echo "Environment variables (with their current values):"
    echo "    SD_PARAMS=$SD_PARAMS       Parameters for FFmpeg's silencedetect filter: noise tolerance and minimal silence duration"
    echo "    MIN_FRAGMENT_DURATION=$MIN_FRAGMENT_DURATION    Minimal fragment duration"
    exit 1
fi

echo "Determining split points..." >& 2

SPLITS=$(
    ffmpeg  -v warning -i "$IN" -af silencedetect="$SD_PARAMS",ametadata=mode=print:file=-:key=lavfi.silence_start -vn -sn  -f s16le  -y /dev/null \
    | grep lavfi.silence_start= \
    | cut -f 2-2 -d= \
    | perl -ne '
        our $prev;
        INIT { $prev = 0.0; }
        chomp;
        if (($_ - $prev) >= $ENV{MIN_FRAGMENT_DURATION}) {
            print "$_,";
            $prev = $_;
        }
    ' \
    | sed 's!,$!!'
)


echo "Splitting points are $SPLITS"

ffmpeg -v warning -i "$IN" -c:a mp3 -map 0 -f segment -segment_times "$SPLITS" "$OUT"