New Media Guides

Audio-compression comes in many formats and each have strengths and weaknessses. It is good to know a little bit about them so you can make smart encoding decisions. Be careful using a program's default compression settings may cause compatibility issues for your intended audience. As a rule of thumb, pick a format based on your specific needs and choose the compression settings that sound the best to your own ear.  Read on to understand what your options are.

There are many lossy audio encoders trying to compete with MP3 but all of them work for the same goal - to find an audio file's perceptual transparency which is the point where higher sound quality becomes inaudible and therefore functionally useless.

Compressed audio formats have thea bility to store text data called metadata. File names can accomplish the same thing but metadata can be read and applied to the files names and directory with one click. ID3 is the way text blocks are attached to an audio file in the form of a tag. Choose Edit Info from the menu in your MP3 player program and fill in the data fields there. The first version of MP3 tags is called ID3v1 and does not give much room to put data in the fields. ID3v2 provides more room but is slower to write since it is at the beginning of the audio file. I recommend filling in bot ID3v1 and ID3v2 since you don't know which tag your listener's playback program will read. If you don't, your audio may show up as Unknown Artist! Always fill in the comment field since its searchable and easy to access by all major programs. This is a good place to put your contact info. ID3v2 also offers a place to put your Web address. Watch this Screenshot Video Tutorial on how to add ID3 tags.

ID3's only apply to MP3 files. Always use the tag format native to the file type you use.

AAC is better than MP3 and is encouraged by MPEG. It is the audio layer of the MPEG-4 standard and is contained inside an MP4 container. It is seen as .m4a or .mp4. Apple uses AAC for iPods, iTunes and iTunes Music Store. An .m4p is one which is copy protected and and locked. AAC has a good file size for the excellent sound quality it provides but does not have as much widespread compatability yet.

WMA, Window Media Audio, is a Microsoft format. They are no better than MP3s and don't have much hardware support. If you have WMA files and want to play them on a Mac, you need to install a 3rd pary QuickTime plug-in since Microsoft discontinued the Windows Media Player for Mac!

Now Ogg Vorbis is a different story! It is an open-source alternative to MP3 and WMA. Vorbis is the audio-componant codec and Ogg is the container. It works great at all it's bit rates, has a flexible metadata system, and is often used for embedded apps like video games since there are no royalty fees to us it. Wikikpedia uses it for everything since it is royalty free and it is goof for anyone maitaining a very large library of compressed audio.

MP3s because of the open-source project LAME encoder. It can vary bit rate through the audio file using more or less bits when needed. The default setting of LAME use CBR or Constant Bit Rate but by using "--abr" command ("--abr 192 for ex.) you can enable the ABR or Average Bit Rate mentioned above. This option does not increase the size of the file! VBR or Variable Bit Rate can handle extreme changes throughout the audio file and is superior to CBR and ABR. It does not increase file size either. Use "--vbr 192" for ex. to enable. VBR is the best to use in most situations.  That is why Ogg Vorbis is so good... it uses VBR encoding by default.

Lame's newest releases are now using numbers instead of names. The lower the number the higher the audio quality. You will be seeing APS ("--v2) and APE ("--v0") now which are both essentially the same.  They look at the file and use filters, noise shaping and other ways to trim the file size the least destructive way. Both will work well.

Alright, now that I have totally confused you, what DO you use for encoding? Many apps offer the ability to export your audio in a compressed format like MP3, Ogg Vorbis, and the like but they don't always have the more advanced encoding options. You can try some of the following to try out the formats mentioned above.

• Panic's Audion (for Mac)
• iTunes - Lame which, by the way, overrides the default encoder of iTunes but you have to start this from the AppleScript menu or it will enbale the default encoder.  (for Mac) 
• Nullsoft's Winamp
• Albert FAber's CDex
• Illustrate's dBpowersAmp
• AndreWiethoff's Exact Audio Copy- Unlike iTunes
• Peter Pawlowski's free foobar2000*** the most recommended
  

 Sharing files with others usually requires sticking with MP3 for compatibility but why you should use LAME encoding with that and one with VBR presets for the best results. The most important thing to remember is keep your original WAV or AIFF file in tact. If you want to change to another format, you don't want to go from one lossy audio format to another since that increases the loss of quality. 

References:

Parts of this article are excerpted from “All is Not Lost,” published in the October 2006 issue of Electronic Musician magazine, and are reprinted with permission of the publisher.