Free Your Music: How to Convert Digital Audio Files
Pages: 1, 2, 3

Which Format to Use?

Even with more sophisticated formats like AAC and WMA, many people prefer plain MP3. The reason is that MP3 is supported by the widest range of hardware and software, and that MP3 files can sound just as good as any of the competing formats.

If your hardware and software support it and you want smaller files without sacrificing quality, go with AAC or Ogg Vorbis. Lossless formats make sense only if you are starting with uncompressed audio and want to retain every bit of information. (For example, you might choose FLAC if you want to make backup copies of your CDs in half the space.)

Table 2 shows typical file sizes for a four-minute song in several formats.

Three Conversion Methods

Figure 1 shows several methods of converting between digital audio formats. Audio capture should be the last resort, because it takes longer, and in some configurations the signal will be converted to analog and then back to digital, which means that more information will be lost and that noise can leak in.

Figure 1. Three methods for converting digital audio files to different formats.

1. Direct Conversion

Direct conversion is the simplest approach, because it converts one format to another without any intermediate steps. Direct conversion to MP3 and other popular formats may be accomplished with a jukebox program such as iTunes or Musicmatch Jukebox, or with an audio editing program such as Sound Forge or Peak.

When you convert a file to another format, the original file usually remains intact. Either delete it to save space, or move it to another location if you want to keep it as a backup. With iTunes, you'll also need to delete the duplicate entries from your music library.

iTunes

iTunes can only convert files that have been imported into its music library. To convert a file to another format in iTunes, first specify the new format and bit rate in the Preferences section.

To do that, select Edit (select iTunes on the Mac) → Preferences and click the Importing tab or button. For MP3, choose MP3 Encoder in the Import Using drop-down menu and choose the bit rate in the Setting menu:

Next, highlight one or more songs in your music library, then right-click and choose Convert Selection to MP3 from the pop-up menu. (If you had specified another format in the preferences screen, "MP3" would be replaced by that format on the pop-up menu.)

iTunes will automatically convert unprotected WMA files when you import them into its music library.

Musicmatch Jukebox

Musicmatch allows you to convert files to different formats without actually importing them into your music library. This is handy if you want to create MP3 files at several different bit rates without cluttering up your music library with duplicate entries.

To convert a file to another format in Musicmatch, select File → Convert Files. In the upper left pane, choose the folder that contains the files to be converted. In the lower left pane, highlight the files to convert. In the upper right pane, specify the destination directory (the folder where the converted files will be stored). Choose the new format from the Destination Data Type drop-down box. Click Start to begin the conversion and the converted files will be listed in the bottom right pane.

2. Burn and Rip

The most reliable way to convert copy-protected songs to plain MP3 (or any other format) is to use your jukebox program to burn them to a standard audio CD, and then rip the files from the CD to the format you want. The drawback of course, is the cost of the blank CDs and the time to burn and rip. (However, this problem is partially solved by using CD-RW discs, which can be erased and reused.) The advantage is that this approach should work every time.

Make sure you configure your jukebox program to burn audio-format CDs. (If you attempt to burn a copy-protected song directly to an MP3 CD, you'll get an error.) In most cases the ID3 tag information (song title, artist, genre, etc.) will be transferred to the new file, but in all cases you'll need to re-embed any album artwork.

3. Audio Capture

The last resort for converting copy-protected audio files to another format is to play them through any program that supports the format and record the audio via your sound card. (This is the same procedure used to record audio from an internet radio stream.) Once the audio is recorded, save it to the new format and import it into your jukebox program.

For this approach to work, you must have a full-duplex sound card, which means that the card can play and record at the same time. Most new sound cards are duplex, but many older sound cards (and many of those built into the motherboards of notebook computers) are not. In this case, use a streamripper program like Audio Hijack or Total Recorder to capture the audio (see Table 3).

Avoid running a cable from the Line Out jack of your sound card to its Line In jack. The sound quality will suffer more and some noise will be added, because the audio will be converted into an analog signal and then back to digital by your sound card before it is captured by your recording program.