Ubuntu – Concatenating several .mp3 files into one .mp3

bashcommand linefiles

As it was suggested here I am using cat command to concatenate several .mp3 files into one .mp3 file.

Imagine, I have following .mp3 files in the current folder:

001001.mp3 001002.mp3 001003.mp3 001004.mp3 001005.mp3

or, like this:

096001.mp3 096002.mp3 096003.mp3 096004.mp3

I need to concatenate these .mp3 files in there ascending sequence, i.e. 001001.mp3+001002.mp3+001003.mp3+etc.

In order to join these .mp3 files into one I am executing following command in the current folder:

cat *.mp3 > final.mp3

I tested the final .mp3 file and it is what I am expected, but I need to be sure that above command picks files in there ascending sequence.

Can I be sure that above command always concatenates files in the ascending sequence?

Thank you Sir!

Best Answer

cat is not the right tool for this job. The MP3 format has all sorts of junk that can lurk at the front and end of the file and this needs to be strippe out. mp3wrap is what you want. It will exclude any metadata in the files and stick the audio together.

sudo apt-get install mp3wrap
mp3wrap output.mp3 *.mp3

Before you do that, run ls *.mp3 to check that they're in the correct order. When I originally wrote this answer (over six years ago!) wildcard globs apparently didn't behave well but I think they do now.

You might need to rename the files if for example, they are numbered but aren't zero-padded, {1-11}.mp3 would be sorted by 1 10 11 2 3 4 5 6 7 8 9. This can be fixed easily.

Related Solutions

Ubuntu – How to combine multiple text files into one text file ordered by date created

It can be done with a python script, with one sidenote: I took the modification date instead of the creation date, since the creation date will almost certainly not match the real creation date: it is the date the file was copied to the computer, while the modification date seems unchanged during copying (see discussion at @cOrps answer). You will have to see if it works in your situation.

If that is acceptable for you, you can use the script below to create a combined file with your notes. It reads the notes, sorts them and appends them to a text file (creates it if it doesn't exist).

The good news is that you can append your new notes to the same file without overwriting the old ones.

Example output:

Mon Sep 29 08:48:31 2014
This is my first note.
As you can read, I am not really awake yet.

----------
Mon Sep 29 09:04:06 2014
It is really time I am going to eat something.
I am a bit hungry.
Making it a bit longer.

----------

How to use:

Copy the script below into an empty file, save it as add_notes.py
change the directories for files_dir (where your notes are) and the file in which you want to save the notes: combined_file (the script creates the file if it doesn't exist)
run the script in a terminal window by typing the command:
```
python3 /path/to/add_notes.py
```

The script:

#!/usr/bin/env python3

import os
import time
import subprocess

# --------------------------------------------------------
files_dir = "/path/to/your/textfiles"
combined_file = "/path/to/your/combined/file.txt"
# ---------------------------------------------------------
notes = []

if not os.path.exists(combined_file):
    subprocess.Popen(["touch", combined_file])

def read_file(file):
    with open(file) as note:
        return note.read()

def append_file(combined_file, text):
    with open(combined_file, "a") as notes:
        notes.write(text)

for root, dirs, files in os.walk(files_dir):
    for name in files:
        subject = root+"/"+name
        cr_date_text = time.ctime(os.path.getmtime(subject))
        cr_date_n = os.stat(subject).st_mtime
        notes.append((cr_date_n, cr_date_text, subject))

notes.sort(key=lambda x: x[0])

for note in notes:
    text = note[1]+"\n"+read_file(note[2])+"\n"+"-"*10+"\n"
    append_file(combined_file, text)

Ubuntu – Configuring youtube-dl

You need to create the config file yourself, it's not created by installation of the program.

Just save from your editor to ~/.config/youtube-dl.conf (note no dash in .config).

The system-wide default configuration file, /etc/youtube-dl.conf, could be created by installing, but is not. That's not a problem, as the file format is not complicated, so an example file is not important.

Not sure what exactly you are doing, but if it's about repeating the download command with a different url, try using the shell history, pressing Up to recall the command, and edit the file name.

(To show your Ubuntu version, use lsb_release -a)