How To Split With Mp3Splt

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A number of the terms and concepts used in this guide are explained in How To Listen With Your CD Player. If you will be using your split files either on your digital audio player or for MP3 disks, be sure to read the caution about the limits on the length of filenames for some players.

The main reason for splitting audio files into smaller ones is convenience: shorter files on your digital audio player or on MP3 disks, or shorter tracks on audio CDs make it easier to find your place again if your player doesn't remember for you.

So if your digital audio player either does remember your position or supports bookmarking, or if your CD player remembers where you were listening when you turn off the player (without removing the disk or pressing the Stop button), then you probably don't need to split the audio book files from !LibriVox.

This guide explains how to use the program !Mp3Splt to split all the audio files -- either in MP3 or Ogg Vorbis format -- which are in a folder, all in a single operation. That is, you will be batch-processing all the files.  !Mp3Splt does not alter your original files. It works by copying the original files and writes new, smaller files during the process of splitting. It also runs fast, so the splitting does not take long to do.

This guide applies to MS Windows, but much of it will be directly applicable to the other systems for which Mp3Splt available: Linux, Mac, and Unix. This information is current as of February 2008. It is unknown if Mp3Splt runs on Windows Vista.

Mp3Splt has a GUI interface for Windows, but it seems to be able to process only one file at a time. Therefore, this guide tells you how to use the command line version (via Windows Command Prompt) since it is faster to use because it supports batch processing. We will do it this way even though entering the commands is a bit cumbersome, especially at first.

See Software We Use to get and install Mp3Splt.

Now that you have installed Mp3Splt and have a set of audio books on your PC, let's get started. The procedure will be:

  1. Start Command Prompt.
  2. Configure Command Prompt to know where you installed Mp3Splt.
  3. Go to the folder containing the audio book files.
  4. Split the files with !Mp3Splt.
  5. Repeat steps 3 and 4 as needed for any other audio books.

The details:

  • Start the Windows program "Command Prompt":
    • Start [button on the task bar] > All Programs > Accessories > Command Prompt
  • Modify this command to reflect where you actually installed Mp3Splt:
path C:\Program Files\mp3splt;%PATH%

Then type the corrected line into the Command Prompt window, followed by the Enter key. This tells Windows where to find Mp3Splt.

If you think you'll being doing this again, you may find it useful to put this command and the others below into a text file from which you can copy and paste them into Command Prompt. Use Notepad to create this file and to open it again for the copy and paste operations.

  • Now, in Command Prompt, go to the folder that has the audio book

files you're going to split. Let's use Through the Looking Glass as an example. This shows the full path to the folder where you have the files, as assumed for this example:


To avoid having to type this in, if you first go to that folder in Windows Explorer (aka, My Computer), you can copy this folder path from the Address bar, usually visible at the top of the window (you may need to reconfigure Explorer to display it: View > Toolbars > Address bar [checked]).

With the folder path copied, type in "cd" (without the quotation marks), plus a space, after the prompt in the Command Prompt window. Now paste in the folder path you just copied (right-click in the window and select Paste from the menu). Based on the example above, you should see this in the Command Prompt window

> cd c:\LibriVox\Carroll__Lewis\Through_the_Looking_Glass

Now press the <Enter> key. The prompt (the text to the left of the flashing underline character ('_') will change to show the folder you're now in:

  • At this point, you are nearly ready to split the files. But first,

you get to decide how you want to split them. Mainly, that means into how many pieces you plan to chop up the audio book. Unfortunately, !Mp3Splt does not allow you to ask directly for the number of pieces you want. What you can ask for is the length of each new file, expressed in time. For example, many commercially-produced audio books on CD have tracks which are each about four minutes long. You can estimate how many pieces you'll get by knowing the total run time (which is listed on the page for each work in the !LibriVox catalog), expressed in minutes, and dividing that number by the time length per piece, in minutes per piece, that you will tell !Mp3Splt to produce. For our example of Through the Looking Glass,

200 minutes / 4 minutes per piece = 50 pieces (approximately)

This estimation is complicated by the fact that the audio book is already divided into multiple files by chapter and further so by the use of the Auto-Adjust option (explained below).

There is no right or wrong value to pick, since it is solely a matter of convenience. If you're planning to make audio CDs from an audio book, then four-minute tracks will give you about twenty tracks on an eighty-minute CD. Twenty tracks are easy to deal with. However, if you're making an MP3 disk of a long novel, you could well end up with 200 or more files if you split at four-minute intervals. That could pose a problem in trying remember and get back to track 82, where you left off listening. In this case, it probably makes sense to increase the length of each piece to reduce the total number of pieces to something more manageable. Experience will show what works best for you.

  • Do the split. The recommended command line has the form
mp3splt -f -t TIME -a -d split *.mp3
Select a specific `TIME` (as explained below), then either type or
copy and paste the modified line into the Command Prompt window.
In our example, this is what you should see:
 .  `c:\LibriVox\Carroll__Lewis\Through_the_Looking_Glass>mp3splt -f -t 4.0 -a -d split *.mp3`
Now press the <Enter> key to start the splitting.  !Mp3Splt writes
status messages in the Command Prompt window as it works.
All the command line options are listed farther below.  Here's an
explanation of the recommended options:
  * `-f`: for MP3 files only, increases precision and is needed if
  the MP3 files are variable bit rate (VBR).
  * `-t TIME`: specifies the length, measured in time, to make each
  piece.  You will replace `TIME` with a numerical value expressed in
  minutes, such as `4.0` for four minutes or `7.30` for seven
  minutes, thirty seconds.  In our example, we picked four minute
  pieces, so the command line will be
   . `mp3splt -f -t 4.0 -a -d split *.mp3`
  * `-a`: automatically adjusts the split points to occur during
  silences, which avoids splitting in the middle of a word.
  Therefore, the pieces will vary in their exact length.
  * `-d split`: writes the split files to a sub-folder named `split`
  (you may pick any name you wish).  The folder will be created if it
  doesn't already exist.  It's more convenient if you don't put the
  split files in the same folder with the original ones.
  * `*.mp3`: process all the MP3 files in the current folder.  If you
  are splitting Ogg Vorbis files, change this to `*.ogg`.
By default, !Mp3Splt uses the original file's name for the split
pieces, adding the time interval of each piece to the name in order
to generate unique filenames. 
For our example, the filename for Chapter 1 is
These are the names of the split pieces (46 characters long, which is
comparatively short):

Complete List of Command Line Options

To see this list of command line options, run !Mp3Splt without any options:

{{{ Mp3Splt 2.1 (2004/Sep/28) by Matteo Trotta <> USAGE (Please read man page for complete documentation)

     mp3splt [OPTIONS] FILE... [BEGIN_TIME] [END_TIME...]
     TIME FORMAT: min.sec[.0-99], even if minutes are over 59.


-w   Splits wrapped files created with Mp3Wrap or AlbumWrap.
-l   Lists the tracks from file without extraction. (Only for wrapped mp3)
-e   Error mode: split mp3 with sync error detection. (For concatenated mp3)
-f   Frame mode (mp3 only): process all frames. For higher precision and VBR.
-c + file.cddb, file.cue or "query". Get splitpoints and filenames from a
     .cddb or .cue file or from Internet ("query"). Use -a to auto-adjust.
-t + TIME: to split files every fixed time len. (TIME format same as above).
-s   Silence detection: automatically find splitpoint. (Use -p for arguments)
-a   Auto-Adjust splitpoints with silence detection. (Use -p for arguments)
-p + PARAMETERS (th, nt, off, min, rm, gap): user arguments for -s and -a.
-o + FORMAT: output filename pattern. Can contain those variables:
     @a: artist, @p: performer (only CUE), @b: album, @t: title, @n: number
-d + DIRNAME: to put all output files in the directory DIRNAME.
-k   Consider input not seekable (slower). Default when input is STDIN (-).
-n   No Tag: does not write ID3v1 or vorbis comment. If you need clean files.
-q   Quiet mode: do not prompt for anything and print less messages.