unix 1 liner to get total minutes of audio

I’m upscaling some audio and the website asked me to state how many minutes I’d need:

In a code block, the one-liner looks like this:

find | grep mp3$ | xargs -L 1 mp3-minutes | math-sum

This one-liner does the following:

1. The find command lists all the files and directories in the current location.

2. The output of find is then piped to grep mp3$ which filters and retains only the lines ending with mp3.

3. The filtered list of mp3 files is then piped to xargs -L 1 mp3-minutes which executes the mp3-minutes command on each mp3 file to find the duration in minutes of each file.

4. The resulting list of durations is then piped to math-sum which sums up all the durations to give a total.

Lets break down each stage with partial outputs.

1. The find command

It lists all files and directories recursively in a directory. The output includes both file and directory names.

Partial Output:

.
./3_Vayikra
./3_Vayikra/7_Kedoshim
./3_Vayikra/7_Kedoshim/c19_v02.mp3
./3_Vayikra/4_Tazria
...

2. The grep mp3$ command

It scans its input lines for matches to the given pattern which is mp3$, and it returns only the lines ending with mp3, i.e. mp3 files.

Partial Output:

./3_Vayikra/7_Kedoshim/c19_v02.mp3
./3_Vayikra/4_Tazria/c12_v04.mp3
./3_Vayikra/4_Tazria/c12_v05.mp3
...

3. The xargs -L 1 mp3-minutes command

xargs is used to build and execute command lines from standard input. Here, it takes each mp3 file (one by one due to -L 1 option) and passes it as an argument to mp3-minutes command, a custom command gpt mostly wrote for me.

#!/usr/env/bin bash

mp3_file="$1"

if [ -f "$mp3_file" ]; then
    duration=$(ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 "$mp3_file")
    minutes=$(bc <<< "scale=2; $duration / 60")
    echo $minutes
else
    exit 1
fi

Partial Output:

5
4
3
...

This hypothetical output assumes that each mp3 files duration represents in minutes.

4. The math-sum command

Finally, the math-sum command sums the durations listed in its input. The final output would be the total duration (i.e., the sum) of all mp3 files.

Final Output:

123

This hypothetical output assumes that the total durations of all mp3 files are 123 minutes.