Outside of the government and the military, the computer world uses the most acronyms. This is especially true for the names of audio compression formats. There are dozens of formats, each with its own reason for being and with its own strengths and weaknesses.
But what do all of those names mean?
And how do you deal with an audio file that you're not familiar with?
We will now look at some popular audio compression formats and some of their characteristics, shall we?
You definitely need to know at least the basics of some of the most common audio formats that you will come across in your everyday life. And they are:
1. Mpeg-1 Audio Layer 3 - MP3
2. Org Vorbis - OGG
3. Free Lossless Audio Coding - FLAC
4. Windows Media Audio - WMA
5. Digital Rights Management - DRM (recently added to WMA format)
6. Advanced Audio Coding - AAC
More on the above listed Audio Formats after the turn...
Popular Audio Compression Formats
MP3
I can't think of anyone who hasn't heard of MP3. Even my parents, who are definitely not the most tech savvy people around, are familiar with it. MP3 is short for MPEG-1 (Moving Picture Experts Group), Audio Layer 3, after the working group tasked with developing digital audio and video encoding standards.
MP3 has become the most popular, and dominant, audio format. It's used everywhere -- from songs ripped from CDs to audio podcasts. Few, if any, portable audio players or software media players don't play MP3 files. And it is extremely hard to find one that doesn't play MP3.
An MP3 file can be quite small. That's because the software used to create an MP3 file, called an encoder, uses what is called lossy compression. The encoder shrinks the file by tossing out bits of audio that, in theory, most people can't hear. When the MP3 file is created with a reasonable bit rate (the number of bits of data converted each second, which helps determine the sound quality), you get near CD-quality sound. However, the more you compress the file, the worse the audio quality becomes. And when you convert an MP3 file to another format, the audio quality noticeably degrades.
One major issue with the MP3 format is that a company named Thomson Consumer Electronics holds the patents for the MP3 format, and charges royalties for its use. Because of this, a number of Open Source software developers decided to create...
Ogg Vorbis
Ogg Vorbis which has the extension .ogg, was developed as a patent-free alternative to MP3. In doing so, the developers managed to "out-MP3" the MP3 format.
Like MP3, Ogg Vorbis uses lossy compression. However, the compression scheme that Ogg Vorbis uses is superior to that used by MP3. You get an equal or greater reduction in file size, but with sound quality better than MP3 when a file is created with the same bit rate.
Ogg Vorbis is widely supported in desktop audio players, including WinAmp, XMMS, RhythmBox, and Quintessential. You can also get a plug-in for the Windows Media Player that gives it solid support for Ogg Vorbis. However, few portable audio players can play back Ogg Vorbis files. Some older players from iRiver, Samsung, and Neuros did support the format, but that support seems to have vanished from newer models.
FLAC
FLAC is short for Free Lossless Audio Coding. Unlike MP3 and Ogg Vorbis, FLAC uses lossless compression to reduce the size of files. This means that no audio is removed when the file is created, resulting in better quality sound. In fact, the sound from a FLAC file is indistinguishable from that of a professionally produced CD. Not only that, but you can convert a FLAC file to any other audio format without the quality of the sound degrading.
While FLAC files are compressed, they're larger than other compressed audio files. A standard audio CD will be compressed to about 300 MB using FLAC. That's really only slightly more than a 50% compression rate. It's good, but not great. The trade off is audio quality. A number of desktop media players and portable audio players support FLAC. A growing number of artists are making their music available as FLAC files.
Lossy compression was important in the days of slow, dial-up Internet access and limited bandwidth. As broadband access becomes ubiquitous, however, lossless encoding is becoming more popular.
WMA
As you might imagine, Microsoft has its own audio format. That format is Windows Media Audio, or WMA for short. It's designed especially for use with the Windows Media Player that's built into the Windows operating system. You can play WMA files in other media players, even ones on other operating systems. Of course, most portable audio players support WMA. One exception, and this shouldn't be a surprise, uh.. huh, it is the Apple iPod.
As far as quality goes, at lower bit rates WMA files are virtually indistinguishable from MP3 or Ogg Vorbis files. At higher bit rates, though, WMA suffers in comparison -- the difference in quality is very noticeable.
Recently, Microsoft added Digital Rights Management (also called DRM) to the WMA format. DRM restricts how and where you can use an audio file that was, say, downloaded from an online music service. For example, one use of DRM in audio files is to allow you to only play that file on a single computer or portable player. DRM has turned a number of users away from WMA and into the arms of MP3.
AAC
AAC (Advanced Audio Coding) is the default file format on the iPod and the iTunes software, and for downloads from the Apple iTunes store. And with good reason -- the compression scheme it uses is better than that of MP3, and AAC can better render the higher frequencies produced by certain musical instruments and by the human voice. With AAC, you get richer audio in a small package. Audio encoded with AAC is noticeably superior to MP3 and WMA. At comparable bit rates, an AAC file generally sounds better than Ogg Vorbis.
AAC is definitely growing in popularity. In addition to support in the iPod and the new Apple iPhone, mobile phone and audio players from other manufacturers are gradually gaining AAC capabilities. But like WMA, AAC also includes Digital Rights Management. This is most notable with tracks bought from the iTunes store. This has prompted an Open Source project called Free Advanced Audio Coding (FAAC) to start developing a DRM-free version of the format.
Dealing with Audio Files
How do you deal with an audio file that you're not familiar with? If none of your media players can play the file, you can try to convert it to a known format like MP3. You can do this with software (Hundreds of Audio Conversion Software available here) or by using an online service like Media-Convert.com and Zamzar. Keep in mind that, depending on the format of the original file, a conversion could result in the loss of some audio quality.
Conclusion
While the compression formats discussed in this post are the most popular ones out there right now, they aren't the only ones in town. A future story will look at some of the other well-known but less frequently used audio formats.
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