Bash - calculate length of all mp3 files in one folder - bash

Question

I have the following command which returns the filenames and lengths of mp3s files:
mp3info -p "%f: %m:%02s\n" *.mp3
How can I use this in a bash script to return the total length (sum) of all mp3 files in a given directory? I would like to have the following notation: mm:ss

Answer 1

I'd go for a three step approach:
instead of printing filename.mp3: mm:ss\n, omit the file name and print the overall seconds
Build arithmetic expression from result, giving you total seconds
divide by 60, round down to get minutes, calculate remainder of seconds.
The first step is easy
mp3info -o '%S'
will do the job. Now, we want things to give us a valid numerical expression of the form
time1+time2+....
so,
mp3info -o '%S + '
would seem wise.
Then, because the last thing mp3info prints will then be a +, let's add a zero:
"$(mp3info -o '%S + ') 0"
and use that string in an arithmetic expression:
total_seconds=$(( $(mp3info -o '%S + ' *.mp3) 0 ))
Now, get the full minutes:
full_minutes=$(( total_seconds / 60 ))
and the remaining seconds
seconds=$(( total_seconds % 60 ))
So the total script would look like
#!/bin/bash
# This code is under GPLv2
# Author: Marcus Müller
total_seconds=$(( $(mp3info -o '%S + ' *.mp3) 0 ))
printf "%02d:%02d\n" $((total_seconds / 60)) $((total_seconds % 60))

Answer 2

Base calculation in mp3info is error prone, as metadata is not real data. Using sox (swiss army tool for audio) you can get directly from mp3 file.
R=0
for a in *.mp3
do
T="$(soxi -D $a 2>-)"
echo $T
[[ "$T" != "" ]] && R="$R + $T"
done
echo $R | bc
if you want hours
echo "($R) / 60" | bc
For long list of mp3 would be better to sum duration at each loop

Answer 3

This Bourne shell one-liner, when used inside a directory containing only music files, will output their total length in seconds with a very high degree of precision:
LENGTH=0; for file in *; do LENGTH="$LENGTH+$(ffprobe -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 "$file" 2>/dev/null)"; done; echo "$LENGTH" | bc
Modified to only output the length of .mp3 files (and thus avoid breaking on the innocuous .docx sitting within our music directory), it would look like this:
LENGTH=0; for file in *.mp3; do if [ -f "$file" ]; then LENGTH="$LENGTH+$(ffprobe -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 "$file" 2>/dev/null)"; fi; done; echo "$LENGTH" | bc
And if, for example, we wanted to output the total length of audio with only several different file extensions, we can do that as well by adding a second wildcard, still avoiding the dreadful, scary .docx:
LENGTH=0; for file in *.mp3 *.ogg; do if [ -f "$file" ]; then LENGTH="$LENGTH+$(ffprobe -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 "$file" 2>/dev/null)"; fi; done; echo "$LENGTH" | bc
Naturally, ffmpeg has to be installed to use either of these.

Answer 4

Here's a variation of #albfan's kind answer with descriptive variable names and syntax highlighting. It works for an entire directory of directories (albums).
#!/bin/bash
TOTAL=0
for ALBUM in *
do
if [ -d "${ALBUM}" ] ; then
ALBUM_TIME=0
echo ${ALBUM}
# Make `cd` quiet
cd "${ALBUM}" &>/dev/null
for TRACK in *.mp3; do
TRACK_TIME="$(soxi -D "${TRACK}" 2>/dev/null)"
# noisy
# echo "Track duration: $TRACK_TIME"
[[ "$TRACK_TIME" != "" ]] && ALBUM_TIME="$ALBUM_TIME + $TRACK_TIME"
done
# Convert summation to a single number for efficiency
ALBUM_TIME=`echo $ALBUM_TIME | bc`
# This has to be two stmts?
echo -n "Album time (min): "; echo 'scale=2;' ${ALBUM_TIME} / 60 | bc
echo # line break
TOTAL="$TOTAL + $ALBUM_TIME"
cd ..
fi
# Evaluate the expression
TOTAL=`echo $TOTAL | bc`
done
echo -n "Total time (hrs): "; echo 'scale=2;' ${TOTAL} / 3600 | bc

Answer 5

A one-liner to rule them all:
mp3info -p '%S\n' *.mp3 | awk '{s+=$1} END {printf"%d:%02d:%02d\n",s/3600,s%3600/60,s%3600%60}'