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Video-enhanced split_by_silence.sh script.
#!/bin/bash
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: split_by_silence_kf input_media.mp4 output_template_%03d.mkv"
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 "There is a simpler version of the sript around"
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 copy -map 0 -reset_timestamps 1 -f segment -segment_times "$SPLITS2" "$OUT"
@vi

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@vi vi commented Jun 6, 2019

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