playlistalo/trimaudio.sh

#!/bin/sh

secmax=240 #max length
sectol=15 #tolerance
secfad=10 #fade

#wav is faster
temp1=$(mktemp /tmp/playlistalo.XXXXXXXX.wav)
temp2=$(mktemp /tmp/playlistalo.XXXXXXXX.wav)
temp3=$(mktemp /tmp/playlistalo.XXXXXXXX.wav)

tempx=$(mktemp /tmp/playlistalo.XXXXXXXX.m4a)

#step 1 rimuove il silenzio
ffmpeg -i "$1" -to $(($secmax + $sectol + 30)) -af "silenceremove=start_periods=1:start_duration=1:start_threshold=-60dB:detection=peak,aformat=dblp,areverse,silenceremove=start_periods=1:start_duration=1:start_threshold=-60dB:detection=peak,aformat=dblp,areverse" -v quiet -y $temp1


#step 2 tronca e sfuma
len=$(ffprobe -show_entries stream=duration -of default=noprint_wrappers=1:nokey=1 -v quiet $temp1)
len=${len%.*}

if [ $len -gt $(($secmax + $sectol)) ];
then 
    ffmpeg -i $temp1 -to $secmax -af "afade=t=out:st=$(($secmax - $secfad)):d=$secfad" -v quiet -y $temp2
    rm $temp1
    mv $temp2 $temp3
else
    mv $temp1 $temp3
fi

#step3 normalizza
#ffmpeg -i $temp3 -af loudnorm $tempx
ffmpeg-normalize -q -f $temp3 -c:a aac -o $tempx
rm $temp3
mv $tempx "$2"