#!/usr/bin/env bash

## REQUIREMENTS mp3info
## SOURCE:  https://unix.stackexchange.com/a/95907/20107
## USAGE: findmp3.sh 3:00 3:15 music/

## Convert MM:SS to seconds.
## The date is random, you can use your birthday if you want.
## The important part is not specifying a time so that 00:00:00
## is returned.
d=$(date -d "1/1/2013" +%s);

## Now add the number of minutes and seconds
## you give as the first argument
min=$(date -d "1/1/2013 00:$1" +%s);
## The same for the second arument
max=$(date -d "1/1/2013 00:$2" +%s);

## Search the target directory for files
## of the correct length.
find "$3" -name "*mp3" |
  while IFS= read -r file; do
   length=$(mp3info -p "%m:%s" "$file");
   ## Convert the actual length of the song (mm:ss format)
   ## to seconds so it can be compared.
   lengthsec=$(date -d "1/1/2013 00:$length" +%s);

   ## Compare the length to the $min and $max
   if [[ ($lengthsec -ge $min ) && ($lengthsec -le $max ) ]]; then
       echo "$file :: $length";
   fi;
done