With a simple tool I developed in C#, I extracted all the wav tracks contained in the BIK video files of a game using the binkconv.exe CLI tool from RAD Video Tools.

In total I have extracted 500 videos then I have 500 directories, each directory contains 4 tracks with this incremental filenaming:

  • VideoName_01.wav
  • VideoName_02.wav
  • VideoName_03.wav
  • VideoName_04.wav


Now I'm stuck with the procedure, because I need to fuse/mix the four wav files into a new unique wav file.

I could do this manually with applications as Audacity, but we are talking about +500 folders in which each one contains 4 wav files, its an insane manual job then I need to find a way to automate it.

I need to do this via commandline application. or with a .Net audio lib that can fuse Wave audio files.


Which free command-line audio editing software could fuse wave files into a new one?.


This is a list of Software that I have installed:

Please note that I'm only pointing that I have installed those apps, but I'm not sure if one of the mentioned apps could do this task via command-line.

I think SoX maybe could be the best approach to do this, but I don't know how to.

  • SoX will do this, as you've suggested. The man page shows: sox short.wav long.wav longer.wav concatenates two audio files. If you add more files on the invocation, they will be concatenated in order supplied. The last argument is the output file.
    – baitisj
    Commented Oct 17, 2015 at 7:23
  • @baitisj But I don't want merge/concatenate, I need to mix them. I found that the command to do it is -m (in lowercase. in uppercase -M is for merge) that mixes the supplied files. thanks a lot please feel free to post an answer to mark it as accepted. Commented Oct 17, 2015 at 7:34

3 Answers 3


You can use FFmpeg:

  • Free and open-source
  • Runs on Windows, OS X, Linux, Android
  • Is CLI so you can batch
  • Can overlay two audio files, e.g. ffmpeg -i input1.mp3 -i input2.mp3 -filter_complex amerge -c:a libmp3lame -q:a 4 output.mp3
  • seems that ffmpeg is a better choice than SoX because at least in the exmaple you'd shown I can specify output encoding parameters to use mp3 or wav or whatever. thanks. Commented Oct 18, 2015 at 5:46

If you really would like to save some effort, install python, use pip install pydub to add pydub and then use os.walk something like:

import os
from pydub import AudioSegment

OUTNAME = "Mixed.wav"
def makemix(audiofiles, dirname):
    """ Mix a list of audio files to Mixed.wav """
    mix = AudioSegment.from_file(os.path.join(dirname, audofiles[0])
    for nextfile in audiofiles[1:]:
        layer = AudioSegment.from_file(os.path.join(dirname, nextfile)
    mix.export(os.path.join(dirname, OUTNAME),  format='wav')

for (root, dirs, files) in os.walk('.'):
    if OUTNAME not in files:
         wavefiles = [fn for fn in files if fn.endswith('.wav')]
         if len(wavefiles) > 1:
              makemix(wavefiles, root)

This will traverse your directories, from the current directory, creating a Mixed.wav anywhere there are two or more wave files and no Mixed.wav so your 500+ plus directories will all get done. You may have to install ffmpeg as well.

  • Free, Gratis & Open Source
  • Work on Windows, OS-X & Linux
  • You could vary the loudness of some of the files if desired, etc.
  • Automates the lot.
  • Can be adapted.
  • You can set it going and go out for a pint or something.
  • 1
    I really appreciate how using Python in conjunction with these libraries makes for implicit clarity. My knee-jerk reaction would have been to use SoX, but I like this solution so much more...
    – baitisj
    Commented Oct 18, 2015 at 8:28

You can use SoX (Sound eXchange):

  • free
  • open source
  • Windows / Linux / Mac
  • CLI
  • Can overlay two audio files, e.g. sox --combine {mix|merge|mix-power} track1.mp3 track2.mp3 output.mp3

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