How To Split Long Audio Files Into Multiple Tracks

“Can longer audio files be divided into shorter tracks?”

This is a question I’m asked many times. Let me explain.

Often we download our audio files to our iPod or mp3 player, and sometimes we even burn them onto a cd to play in the car. If you’re like me, things happen and we get interrupted. The next time we go to listen to the recording we were part way through, we have to start again – from the beginning. By now, we now the first ten minutes by heart and we wonder if we’ll ever hear the end.

That’s one big reason why we would want to break down longer audio files into a number of shorter tracks.

Another reason is – if we want to upload the file onto our website – or have a file for customers to download, we may want to reduce the file size. This can be achieved by having a number of smaller files.

So, here are a couple of options you may choose to use to break one longer audio file into a number of shorter ones.

Using Audacity:

A much overlooked feature within Audacity is the ability to automatically split an audio track every X number of seconds, or if you prefer, you can split the track X number of times. This will allow you to “seek” to a certain part in your recording by using the ‘next track’ button in your cd player or the chapter forward arrow on your mp3 player.

Here’s how you can perform this.

1.  Launch Audacity

2.  Go to File > Open and browse for and select the desired audio file.

3.  Go to Analyze > Regular Interval Labels.

4.  Choose “Label interval” for “Label placement method” and enter the interval (in seconds) for the length of desired splits into separate files.

5.  Go to File > Export Multiple

6.  Choose the “Export format” and configure as desired (eg, mp3, 128 kbps CBR or if preferred wav 16 bit PCM. The latter is preferable if you are burning a cd – it may not be compatible with all cd players. Another advantage for this is having a WAV file exported in Audacity means your burning program won’t have to convert them before burning as an audio cd. The export process is also quicker when using WAV instead of mp3. Quality loss is minimal.)

7.  Choose “Labels” under “Split files based on”.  (Note: Don’t check “Include audio before first label”.)  Choose “Numbering consecutively” under “Name files” and type in the name that you wish to use for the mp3 files.

8.  Click “Export”.

9.  You need to continue clicking “okay” for each separate audio track as Audacity is wanting you to enter tag information for every single file. (This is a pain! but necessary … so just do it!)

Because audacity is now exporting your files, a different window will pop up for each separate file. That’s okay – just let it go and don’t try to cancel during this process. It might take a while, depending on the file size, so go and make a cuppa and come back if you wish.

10. Browse to the folder where you saved the files to. You should now have a group of files numbered sequentially and named according to your settings.

11. The final step – burn the mp3 files to a data cd or burn to an audio cd for regular players, or save to your iPod or mp3 player. Make sure you’ve placed them in the correct order before burning or saving.

Note: As your audio files are being re-compressed during this process, you may experience a slight loss of quality. Honestly, this isn’t really noticeable and worth it to be able to select your best starting point each time.

If you wish, you can download Audacity here. Also download the Lame MP3 encoder to enable you to export your files as mp3′s.

Using Mp3splt-gtk:

This is a free multi-platform tool which enables you to split large mp3 or OGG files without the need to re-encode. There are a number of ways to perform this including:

a.  Autodetecting silences

b.  Use a local CDDB or CUE file

c.  Download album or track length info from freedb.org (if files are commercially available recordings)

Other options include splitting the track by fixed time segments as well as unwrapping mp3 wrap files.

Despite the multiple ways of splitting files, the method I feel you’d be most interested in is splitting by autodetecting silences.

It will be necessary to provide the parameters such as

1.  the threshold level to mark a ‘silence’

2.  the cutpoint offset (0 being the beginning of the silence, and 1 is the end)

3.  minimum silence to detect

4.  how many silences to process

5.  whether to remove the silences between tracks.

You may also wish to visually create and edit your splitpoints by using the ‘player’ tab or by typing in time values (seconds or minutes).

You can download this free Mp3splt-gtk program here.