Linux MP3 – Join Multiple MP3 Files Losslessly

debianlinuxmp3Ubuntu

How do you join multiple MP3 files into one? "cat" and "mp3wrap" are no good as they produce non standard MP3 files. I know I can use audacity, but when you have 1000's of MP3 files to join into one, it takes too long.

Any suggestions?

Best Answer

Use ffmpeg or a similar tool to convert all of your MP3s into a consistent format, e.g.

ffmpeg -i originalA.mp3 -f mp3 -ab 128kb -ar 44100 -ac 2 intermediateA.mp3 ffmpeg -i originalB.mp3 -f mp3 -ab 128kb -ar 44100 -ac 2 intermediateB.mp3

Then, at runtime, concat your files together:

cat intermediateA.mp3 intermediateB.mp3 > output.mp3

Finally, run them through the tool MP3Val to fix any stream errors without forcing a full re-encode:

mp3val output.mp3 -f -nb
(source)

Related Solutions

Linux – How to physically reorder files `03.mp3 01.mp3 02.mp3` (`ls -f`) in a directory

It's unlikely that you'll be able to do this on ext4. Unlike FAT(32), which used a linear table of files in a directory, modern filesystems use complex structures such as B+tree (NTFS, XFS) or hashed B-tree (ext3/4), where all entries are sorted according to a specific algorithm.

In particular, ext3/4 sorts files according to the hash value of their name, so you always get the same files in the same order. It's possible to disable the dir_index feature via tune2fs, but it might cost you performance if you have directories containing many files.

A very basic command for this could be cp dir/* otherdir/, where the shell sorts names when expanding arguments, and cp simply copies them in the order given.

Something more complex, for copying subdirectories:

#!/usr/bin/env bash
srcdir=$1
destdir=$2

find "$srcdir" \( -type d -printf "0dir %P\0" \) \
            -o \( -type f -printf "1file %P\0" \) |
sort -z | while read -r -d '' type path; do
    case $type in
        "0dir") mkdir -vp "$destdir/$path";;
        "1file") cp -v "$srcdir/$path" "$destdir/$path";;
    esac
done

FFMPEG: m4a to mp3 conversion using multiple cores

GNU Parallel sounds exactly like what you are looking for.

Here is an example of how you could use GNU Parallel (assuming you already have a directory with all your *.m4a files named videos) using your original commands:

find /path/to/videos -name "*.m4a" | parallel 'ffmpeg -i {} -acodec libmp3lame {.}.mp3'

Two things to explain:

1: The output of the find command (i.e. the list of .m4a files to convert) will be piped into the parallel command, which will in turn (by default) execute as many jobs as there are cores. In essence it is splitting the output from the find command, and distributing it across the different jobs to work on.

2: Per the GNU Parallel Tutorial, {} is where your arguments will go, {.} will substitute in your arguments and remove the terminal extension (in this case the .m4a), and your output will be the original file name but with .mp3 extension.

NOTE: This example will write all your converted files to where your original files are. If this is an issue, then merely pass a directory to store the converted files in the argument string containing the ffmpeg command:

find /path/to/videos -name "*.m4a" | parallel 'ffmpeg -i {} -acodec libmp3lame /path/to/converted/vids/{.}.mp3'