Use CDex to Add WAV Headers to MP3 Files

When working with adding sound within PowerPoint, be it adding sound to an animation or even adding sound to a slide transition, you'll realize that only WAV files can be used as sounds in either of these scenarios. What's more—the same WAV file is always larger in size than its MP3 alternative and since animation and transition sounds are always embedded within PowerPoint, you can end up with really large PowerPoint file sizes! Note that adding an MP3 file for animation or transition sounds is normally not doable since PowerPoint won't accept a file that has an MP3 file extension, and this is unfortunate because MP3 files can be almost 10x smaller than WAV files.

So, can we trick PowerPoint in allowing an MP3 file to be used for animation or transition sounds? Yes indeed, here is a solution using a free program called CDex that adds a header to your MP3 file and renames it with the WAV file extension. The file size still remains the same. This header is added within the file's binary format and is transparent to you as a user; PowerPoint though is convinced that this is a WAV file!

Note that CDex only works with PCs not with Macs.

Download and install CDex. Before starting, you need a MP3 file to work on. We used a sample MP3 file from Office.com. Follow these steps to add a header to an MP3 file using CDex:

1. Go to your Windows Start menu and choose All Programs | CDex | CDex.
2. This launches the CDex interface, as shown in Figure 1.
3. 
   Figure 1: CDex interface
3. To add a header to an MP3 file, chose the Convert | Add a RIFF -WAV header(s) to MP2 or MP3 file(s) menu option, as shown in Figure 2.
4. 
   Figure 2: Choose the Add a RIFF -WAV header(s) to MP2 or MP3 file(s) menu option
Tip: You can also start with a conventional WAV file and then convert it to MP3 within CDex. To do that, choose the Convert | Convert WAV file(s) to Compressed Audio File(s) menu option.
4. This brings up the Open dialog, as you can see in Figure 3. Within this dialog box use the Browse button (highlighted in red within Figure 3) to browse and add the MP3 file(s) you want to convert. Optionally, you can similarly add more MP3 files if you want to do a batch conversion.
5. 
   Figure 3: Open dialog box
5. Once the MP3 file(s) is/are added to the Available Files list, select the file(s) you want to convert. Then click the Convert button (highlighted in blue within Figure 3). The converted files will typically be in the same folder as the original and will have a WAV suffix. Note that the converted file is still an MP3 file with the same size as the original file. However, it has a WAV file extension that can easily convince PowerPoint that you are adding a WAV (and not an MP3) as your transition or animation sound.