Understanding Digital Media Formats

[Wayde]

Have you ever tried to make sense of all the different types of digital audio and video? Ever thought of creating a digital media library of your own but feel a little overwhelmed by all the formats?

Welcome to the first installment of a series that looks at digital audio and what it all means to you. Who can deny the convenience of storing your entire library of music in something size of a cigarette pack? But some digital audio formats can backup CDs in audio quality that rivals (or duplicates) that of the original, while others are about as pleasant as cat under the couch. The first step in understanding digital media is to know your codecs.

Digital audio formats are actually codecs. Codec is a portmanteau word or a word originally made up of other words - like brunch. Codec comes from Code - Decode which is what's happening when someone rips (encodes) a CD into another digital format and then listens to it later (decode). Here's a quick outline of many of the most popular codecs.

Real Audio: RealPlayer has been around a long time. You may have clicked an audio or video stream that prompted you to install the Real Player codec on your computer. It's used mainly for streaming media from a website or internet radio. It’s a low bandwidth encoding method so it won't sound very good, not a problem for a student wanting to hear a recording a famous speech by JFK. Its strength is that it can stream music through the web even under adverse conditions such as dial-up. But if you care about sound quality there are better codecs.

WAV: Short for wave. This format was created by IBM and Microsoft years ago and has annoyed Windows users with bleeps and blurps ever since. It's not suitable for encoding digital music because WAV files are too large. WAV is sometimes worthwhile as a temporary step when transcoding. When you want to convert a digital audio file to another format but the codec won't recognize the format your digital music is in, you must first convert it to something your codec can see. WAV is so ubiquitous when using Windows that many codec tools will read it and can encode to it.

AIFF: This is the Apple equivalent to a WAV file. It has the same disadvantage as WAV in that it produces very large files.

MPEG: Pronounced M-Peg, an acronym for Moving Pictures Experts Group. The MPEG produced a family of codecs that ushered in the golden age of digital media compression we now enjoy. The groups' codecs are used on DVDs, digital radio, satellite and cable TV and through the internet. MPEG consists of a coalition of companies interested in high quality compressed audio visual media including: Dolby Labs, Fraunhofer (FhG), AT&T, Nokia and Sony.

Mpeg Details

MPEG developed the first widely adopted lossy audio video compression, MPEG version 1. Lossy compression simply means that after the audio or video is encoded the result is a relatively small file with minimal loss of quality. When we're dealing with something like an MP3 (or AAC) the loss of fidelity is proportionate to the amount of compression applied and measured in bits per second, the more bits per second the more data in the file hence higher quality. Smaller files result in greater loss of fidelity and therein lay the rub in dealing with digital media.

A 128 kilobit per second (kbps) MP3 is a nominal amount of compression and average for what you'll find online at sources like iTunes. 128 bit MP3s fit nicely through the internet and has an audio quality that sounds acceptable through most earbuds played back through the average portable player. But to the discerning ear played back on a home theater audio system a 128 bit MP3 is the acoustic equivalent of unwrapping a Little Debbie snack cake at a fine dining establishment.

MP3: The MP3 was derived from the first version of its codec Mpeg1. MP3 is by far the most popular format of digitally encoded music. The .mp3 file is the most widely used digital audio format on the internet. Nearly all portable digital media players can playback an MP3 as it's the first real breakthrough in lossy audio encoding, MP3 is also known as MPEG-1, layer 3.

AAC: Advanced Audio Coding is the audio core of the Mpeg-4. This is a more advanced audio codec than the MP3 which is derived from Mpeg-1 and its most commonly used by Apple in its iPod which can read AAC files. As a more advanced codec you'll get slightly higher fidelity at a slightly lower bit rate.
Next we'll delve into more Digital Audio codecs and explore of great interest to audiophiles there are a few that are lossless.

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