Another great article from Scrathlive!

Take off the bullshit glasses and listen to the good stuff below:

What is encoding?

Encoding is the process of changing the
format digital audio is stored in. There are two broad types of
encoding; compressed and uncompressed. Uncompressed audio is mainly
found in the PCM
format of audio CDs. For the most part, audio encoding means going from
uncompressed PCM, to some kind of compressed audio format.

Compressed audio is split into two groups, lossless and lossy.
Losslessly compressed audio can be decoded back into the exact
uncompressed audio you started with. This is useful for archiving audio
at the highest quality possible, and for people for whom storage space
is not an issue. Lossy compression involves some loss of information hence the term "lossy".

Some common audio formats

<u><b>Uncompressed</b></u>            <u><b>Compressed - Lossless</b></u>          <u><b>Compressed - Lossy</b></u><br />Audio CD                Apple Lossless Audio           Mp3<br />Audio DVD               TTA                            AAC<br />PCM WAV and AIFF        FLAC                           WMA<br />Record                  Monkey's Audio                 Mini Disc (ATRAC)<br />Cassette                Shorten<br />DAT                     WavPack</pre><h1>Re-Encoding</h1>A common question on the <a href="http://www.scratchlive.net/forum" title="http://www.scratchlive.net/forum" target="_blank">ScratchLIVE.net forums</a>
is if transcoding (converting a file from one lossy format to another),
or re-encoding into the same format with better settings will result in
a better quality file. The answer is a resounding "NO". The artifacts
from the initial lossy encoding will still be present, along with new
(possibly far worse) ones. It is a good rule of thumb to only ever
lossy encode from an uncompressed source.<br />
<br />
<h2>An example of transcoding</h2>Audio CD ➞ AAC ➞ MP3<br />
<br />
In the above example, the transcoding step is from AAC to MP3. The
quality of encoding will be greatly reduced in the final result. The
preferred alternative would be to go back to the original CD:<br />
<br />
Audio CD ➞ MP3<h1>Useful audio encoding links</h1><a href="http://en.wikipedia.org/wiki/Audio_compression_%28data%29" title="http://en.wikipedia.org/wiki/Audio_compression_%28data%29" target="_blank">Wikipedia  audio compression article</a><br />
<a href="http://arstechnica.com/articles/paedia/The-AudioFile-basicsof-uncompressed-digital-audio.ars" title="http://arstechnica.com/articles/paedia/The-AudioFile-basicsof-uncompressed-digital-audio.ars" target="_blank">Ars Technica article on digital audio</a><br />
<a href="http://en.wikipedia.org/wiki/Sound_recording_and_reproduction" title="http://en.wikipedia.org/wiki/Sound_recording_and_reproduction" target="_blank">Wikipedia  sound recording and reproduction article</a><br /><br /><h1>File formats and codecs</h1><h1>Uncompressed</h1><h2>WAV and AIFF</h2>WAV
and AIFF are the standard file formats for uncompressed PCM audio.
Generally they will be the source material for your lossy encoded
files, unless you skip the step of making uncompressed files and go
straight from CD to lossy compressed encodings. <br />
<br />
The best practice would be to archive your uncompressed files
somewhere, and keep them to make new encodings from as technology
improves, or for purposes of keeping a backup.<br />
<br />
For more information check out the Wikpedia pages on them: <a href="http://en.wikipedia.org/wiki/WAV" title="http://en.wikipedia.org/wiki/WAV" target="_blank">WAV</a> and <a href="http://en.wikipedia.org/wiki/Audio_Interchange_File_Format" title="http://en.wikipedia.org/wiki/Audio_Interchange_File_Format" target="_blank">AIFF</a><br />
<br />
<h1>Compressed</h1><h2>MP3</h2>MP3 is the compressed format most
prevalent on the internet and most universally supported by media
players. It uses lossy compression to greatly reduce the amount of data
needed to store the audio. For DJing applications, care should be taken
not to reduce the amount of data too far, to maintain the audio quality
of your files.<br />
<br />
<h2>AAC</h2>AAC is a more recent technology, intended as the successor
to MP3. It is the default encoder in Apple iTunes and is part of the
MPEG-4 specification. While AAC has many improvements over MP3, it is
less widely adopted at the time of writing, for instance AAC support in
Scratch LIVE will be added in version 1.8, and isn't currently on
release.<br />
<h2>Ogg Vorbis</h2>Ogg is an open source container format which can
contain all sorts of media, Vorbis is the open source lossy audio
compression format which uses the Ogg containers.<br />
<br />
Check out more information on Ogg Vorbis here:<br />
  <br />
<a href="http://en.wikipedia.org/wiki/Ogg" title="http://en.wikipedia.org/wiki/Ogg" target="_blank">Ogg</a><br />
<a href="http://en.wikipedia.org/wiki/Vorbis" title="http://en.wikipedia.org/wiki/Vorbis" target="_blank">Vorbis</a><br /><br /><h1>Encoding tools</h1><h2>What is an encoding tool?</h2>Encoding tools
are programs which create audio files in a particular format, generally
with options for adjusting various aspects of the file encoding
process. <br />
<br />
Here are a couple of basic options for getting started with making your own files.<br />
<br />
<h2>iTunes</h2>iTunes comes pre-installed on all Mac computers, and is
available free from Apple for Windows. iTunes can encode files of
various formats and settings<br />
<br />
For more information on iTunes, check out the <a href="http://scratchlive.net/articles/?article_id=3" title="http://scratchlive.net/articles/?article_id=3" target="_blank">introduction to iTunes</a> article.<br />
<br />
<h2>LAME Frontends</h2><a href="http://lame.sourceforge.net/index.php" title="http://lame.sourceforge.net/index.php" target="_blank">LAME</a> is a free MP3 encoder which is generally considered to give the highest quality results for VBR encodings at a given bitrate.<br />
<br />
<a href="http://www.dors.de/razorlame/index.php" title="http://www.dors.de/razorlame/index.php" target="_blank">RazorLame</a> is a LAME frontend for Windows, however it doesn't rip CDs.<br />
<br />
<a href="http://www.sbooth.org/Max/" title="http://www.sbooth.org/Max/" target="_blank">Max</a> is a Mac LAME frontend which includes CD ripping functionality.<br /><br /><h1>Encoder settings</h1><h2>Bitrate</h2>A file's bitrate is how many bits per second are used to represent the audio. So a 128 kbps file uses <i>128</i>,000 <i>bits per second</i> to encode an audio signal. The more bits used, the less information is discarded to create a compressed file.<br />
<br />
Bitrate therefore determines the size of a file. Here are a couple of examples at various bitrates:<br />
<br />
<pre><u><b>16bit 44.1KHz Stereo</b></u><br /><b>File Type</b>         <b>Uncompressed</b>         <b>320kps</b>             <b>192kps</b><br />5 Min Track             50 MB           11 MB             7 MB<br />15 Min Track            150 MB          33 MB             21 MB<br />80 Min Mixtape          700 MB          183 MB            110 MB<br />

Variable Bitrate

Variable bitrate (VBR) is a way of saving disk space. The bitrate
setting chosen is used as the maximum bitrate to be used, and when the
encoding algorithm decides it can get away with using less bits to
accurately represent a part of the audio, it does. Thus the bitrate
changes over the length of the file, hence the term variable bitrate.
Variable bitrate files can take slightly more CPU to decode than
constant bitrate files, due to the changing amount of bits.

Constant Bitrate

The meaning of constant bitrate or CBR is obvious. The same number of bits are used to encode every second of audio.

Wikipedia article on bitrate

Joint Stereo

Joint stereo is a technique where instead of encoding the left and right channels separately, the sum and difference
of both are encoded instead. Since both sides will tend to be very
similar, the difference will not require a lot of data, and thus the
size of the file is smaller than 'normal' stereo. This means more of
the bits can be used for the 'important' information, and thus the
quality will tend to be improved. It should be noted that some experts
think joint stereo techniques can impart artifacts on the audio, but in
general joint stereo is a good thing.

Joint Stereo: The Myths and The Realities

Some recommended starting points

If you have plenty of storage,
and want the best quality you can, the standard is 320 kbps CBR Joint
Stereo. If you find that you don't have enough room to store all your
music at that quality, a good compromise would be 224 kbps VBR joint
stereo.

It seems like a well established fact that you can't get away with bitrates lower than 192 kbps in a performance setting.

Beyond those starting points, it's up to you to listen to your encodings, and see what you like or not!

Good times :-)