I have some audio recorded in Audacity 3.2.3 that I have exported as an mp3 and a flac. Then I have this file split_by_silence.sh
Which has hardcoded input path values that take an input file, split it by detecting silence, and then finally run an ffmpeg command to split the files. If you save the below code into a file split.sh, you can call it with the command $ ./split_by_silence.sh "value1" "value2"
# ./split_by_silence.sh "full_lowq.flac" %03d_output.flac
#IN=$1
#OUT=$2
OUT="%03d_output.flac"
IN="/mnt/e/martinradio/rips/vinyl/WIP/Dogs On Fire (1983, Vinyl)/dog on fire.flac"
OUTPUT_LOCATION="/mnt/e/martinradio/rips/vinyl/WIP/Dogs On Fire (1983, Vinyl)/"
true ${SD_PARAMS:="-18dB"};
true ${MIN_FRAGMENT_DURATION:="20"};
export MIN_FRAGMENT_DURATION
if [ -z "$OUT" ]; then
echo "Usage: split_by_silence.sh full.mp3 output_template_%03d.mp3"
echo "Depends on FFmpeg, Bash, Awk, Perl 5. Not tested on Mac or Windows."
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
#
# get comma separated list of split points (use ffmpeg to determine points where audio is at SD_PARAMS [-18db] )
#
echo "_______________________"
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 "SPLITS= $SPLITS"
#
# Add 5 seconds to each of the comma separated numbers
#
# Convert the comma-separated string into an array
arr=($(echo $SPLITS | tr ',' '\n'))
# Initialize a new array to store the results
new_arr=()
# Iterate through each element and add 5 seconds of padding
for i in "${arr[@]}"; do
result=$(echo "$i + 5" | bc -l)
new_arr+=("$result")
done
# Convert the array back into a comma-separated string
NEW_SPLITS=$(IFS=,; echo "${new_arr[*]}")
# Print the result
echo "NEW_SPLITS= $NEW_SPLITS"
SPLITS=$NEW_SPLITS
#
# Print how many tracks should be exported
#
res="${SPLITS//[^,]}"
CHARCOUNT="${#res}"
num=$((CHARCOUNT + 2))
echo "Exporting $num tracks"
echo "_______________________"
#
# Split audio into individual tracks
#
current_directory=$(pwd)
cd "$OUTPUT_LOCATION"
echo "Running ffmpeg command: "
ffmpeg -i "$IN" -c copy -map 0 -f segment -segment_times "$SPLITS" "$OUT"
#ffmpeg -i "full_lowq.flac" -c copy -map 0 -f segment -segment_times "302.825,552.017" "%03d_output.flac"
echo "Done."
cd $current_directory
echo "running flac command"
# check flac file intrgrity
If I call this code for my flac file:
OUT="%03d_output.flac"
IN="/mnt/e/martinradio/rips/vinyl/WIP/Dogs On Fire (1983, Vinyl)/dog on fire.flac"
The outputted files have an incorrect metadata for the length. They all report as having the same length, but if i import any of them into audacity, the file has a correct length.
but if i run this for my mp3 file, we can see the correct length metadata:
OUT="%03d_output.mp3"
IN="/mnt/e/martinradio/rips/vinyl/WIP/Dogs On Fire (1983, Vinyl)/dogs on fire.mp3"
So there is something with my ffmpeg command that causes it to export flac files with wrong 'length' metadata
ffmpeg -i "$IN" -c copy -map 0 -f segment -segment_times "$SPLITS" "$OUT"
I've tried with the flac example to change -c copy to -c:a flac, but that just gives every output flac file a length of 00:00:00
is it a problem with my ffmpeg command? Or my files? https://file.io/tIFsa1l70076 it works for mp3 files just fine, why does it have this issue with flac?
