Video-enhanced split_by_silence.sh script.

splitaudiokf.sh

#!/bin/bash

# updated from original to encode as mp3, renamed 'splitaudiokf', and improved usage file

IN=$1
OUT=$2

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

if [ -z "$OUT" ]; then
    echo "Usage: splitaudiokf <input_file> <output_template>"
    echo ""
    echo "Depends on FFmpeg, Bash, Awk, Perl 5. Not tested on Mac or Windows."
    echo "This version of the script takes into account video keyframes by adjusting splitting points next keyframes."
    echo ""
    echo "Arguments:"
    echo "  <input_file>                Media file with silences, to split"
    echo "  <output_template>           A printf-style string such as output-%03d.mp3 which increments for each output file"
    echo ""
    echo "Environment variables (with their current values):"
    echo "  SD_PARAMS=$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 "Enumerating keyframes..." >& 2

KFS=$(
    ffprobe -v warning -select_streams v -show_packets -of  csv "$IN"  \
    | perl -wne '
        @a=(split /,/);
        print $a[4], " "
            if  $a[13] =~ /^K/ 
            and $a[2]==0;
    '
)

echo "Detected $(echo $KFS | wc -w) keyframes" >&2


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 -wne '
        our $prev;
        INIT { $prev = 0.0; }
        chomp;
        if (($_ - $prev) >= $ENV{MIN_FRAGMENT_DURATION}) {
            print "$_,";
            $prev = $_;
        }
    ' \
    | sed 's!,$!!'
)

echo "Splitting points are $SPLITS"

echo "Adjusting splitting points to keyframes..." >&2

export SPLITS
export KFS

SPLITS2=$(perl -we '
    our @kfs = split / /, $ENV{"KFS"};
    our @spl = split /,/, $ENV{"SPLITS"};

    my $k = 0;
    foreach $s (@spl) {
        last if $k > $#kfs;
        while (1) {
            last if $k > $#kfs;
            my $kf = $kfs[$k];
            $k += 1;

            if ($kf >= $s) {
                #print STDERR "$s->$kf\n";
                print "$kf,";
                last;
            }
        }
    }
' | sed 's!,$!!')

echo "Adjusted splitting points are $SPLITS2"

ffmpeg -v warning -i "$IN" -c:a mp3 -map 0 -reset_timestamps 1 -f segment -segment_times "$SPLITS2" "$OUT"