A helpful guide for Digital and Internet Video Producers

A Multi-part series of articles
By Lorraine Grula - Internet Video Gal

Part 5 - Digital Audio

No list of digital file formats would be complete without the glorious MP3, which is actually MPEG-1, Audio Layer 3, but who’s counting?

MP3 is by far the most popular codec for storing and transferring music, made ubiquitous by iPods and other MP3 players.

To compress the file, MP3 removes frequencies judged to be essentially inaudible. For most human ears, MP3 manages to deliver near-CD sound quality in a file that's only about a tenth or twelfth the size of a corresponding uncompressed WAV file.

When creating an MP3 file, you can select varying amounts of compression depending on the desired file size and sound quality.

mp3Pro
An updated version of the original MP3 codec. Small, low-bitrate mp3Pro files contain much more high-frequency detail than standard MP3 files encoded at similar low bitrates.

The high-frequency portion of the audio signal is handled by an advanced and extremely efficient coding process known as Spectral Band Replication (SBR), while the rest of the signal is encoded as a regular MP3.

That means that when you play an mp3Pro file on non-mp3Pro-compatible software, it’ll play, but you'll only hear the non-SBR-encoded portions. This means you'll lose the highs altogether. Bummer.

The solution is to use a fully compatible audio program, such as Windows Media Player and mp3Pro files will deliver great sound quality with extremely low bitrates.

Wave at Me Baby!
.WAV file extension identifies a standard audio format for Windows operating systems that’s used for storing high-quality, uncompressed sound. WAV files are large since they are uncompressed. They provide extremely high quality audio.

.WAV contains CD-quality (44.1 KHz/16-bit) audio signals and require relatively large amounts of memory — roughly 10 MB per minute of music.

WAV is what’s known as a container format, or one which holds different kinds of data within its file. Container formats are gaining in popularity because of their multimedia applications, as well as their cross-platform compatibility. For example, a single container file can hold chapter information, hyperlinks and subtitles, as well as different kinds of codecs that enable various types of players to read the file. This all makes it more convenient for the user.

Windows Media Audio, file extension .WMA
Like .wav, Windows Media Audio is a Microsoft product so is one of today's most pervasive Internet audio formats. Though not as popular as MP3, proponents of the lossy compression format claim it outperforms MP3 in sound quality, particularly with files encoded at lower bitrates such as 64 or 96 Kbps.

This performance advantage makes it handy for applications like portable digital audio players, where total play time is limited by a finite amount of internal memory. Although the technical specs will put WMA ahead of MP3, many human ears could never tell the difference.

The Windows Media Audio format features built-in copy protection abilities, unlike MP3. Windows Vista, the new Microsoft operating system, contains built in support for WMA encoding so you can easily create WMA music files. No doubt Mr. Gates wants WMA to be even more common than it is.

That’s all for this part 5 of our multi-part helpful guide on digital file formats.

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