Choosing a File Format
Once you decide between lossy and lossless compression, you can then start examining available file formats. Not all formats offer both lossy and lossless options.
Let’s start with lossy formats, which is the probable choice for a majority of users, especially those with portable devices. There are three popular file formats that offer lossy compression:
- AAC (Advanced Audio Coding). This is the proprietary audio format used by Apple for its iPod and iPhone devices, and for the tracks sold in the iTunes Store. AAC offers slightly better sound quality than similar-bitrate MP3 files.
- MP3. The MP3 format is the most widely-used digital audio format today, with a decent compromise between small file size and sound quality. The primary advantage of MP3 is its universality; unlike most other file formats, just about every digital music player and player program can handle MP3-format music.
- WMA (Windows Media Audio.) This is Microsoft's digital audio format, promoted as an MP3 alternative with similar audio quality at half the file size. That may be stretching it a bit, but WMA does typically offer a slightly better compromise between compression and quality than you find with MP3 files.
If you prefer the higher fidelity available with lossless compression, you also have three popular file formats to choose from – although they’re a slightly different three than for lossy compression:
- Apple Lossless (AKA AAC Lossless). This is the lossless version of Apple’s AAC format, compatible with Apple's iTunes and iPod, as well as any Apple-compatible device. The best lossless option for anyone mired in the Apple ecosystem, as Apple Lossless files work just fine with all Apple products.
- FLAC (Free Lossless Codec). This is an open-source lossless format, popular format among audiophiles. The FLAC format can actually reproduce music at higher-than-CD fidelity – so-called high definition audio – when ripped with the right settings.
- WMA Lossless. This is Microsoft's lossless compression format, a good option if you’re wedded to the world of Windows. WMA Lossless uses the same WMA file extension as normal Windows Media Audio files, and plays on any player compatible with the WMA format.
Note that the MP3 format doesn’t have a lossless option, nor does FLAC have a lossy one. Both AAC and WMA have both lossless and lossy versions.
Which file format you choose, then, depends on your choice of lossy or lossless compression, and the devices and apps you intend to use.