Glossary

MD stands for MiniDisc, a digital format that uses Sony proprietary ATRAC (Adaptive TRansform Acoustic Coding) data compression to fit up to 74 minutes of digital audio on a 64mm, recordable, erasable magneto-optical disk. Commercial prerecorded MD releases use an optical-only playback format and are not recordable. MD audio is compressed during recording, using a lossy compression, so that the audio quality has lower fidelity than the same data written to a CD. Using Xilisoft Sound Recorder, you can record music from MD.

Audio Interchange File Format. A common Macintosh audio file format. It can be mono or stereo, at sampling rates up to 48kHz. AIFF files are QuickTime-compatible and support uncompressed mono, stereo, and multichannel audio at many different resolutions and sampling rates, including the CD standard. It was designed to serve as a universal interchange format that allows any program to open a digital recording created by any other program. AIFF is high-quality audio, used in pro-level Mac and PC audio software. As AIFF is a standard for uncompressed audio, Apple introduced AIFF-C which can use MACE and IMA/ADPCM compression with ratios as high as 6:1, but the audio sound quality suffers.

The audio file format used by Apple in their popular iTunes Music Store often appears on your system with the .M4A filename extension. M4A can produce better audio quality than MP3 using less physical space for the files.

MIDI stands for Musical Instrument Digital Interface.
MIDI is a specification for the types of control signals that can be sent from one electronic music device to another. MIDI is a serial protocol, with a word length of 30 bits and a transmission speed of 32 kbps. MIDI messages are either channel messages or system messages, the first of which describes the actual musical content of the sound, and all other synthesizer actions affecting that sound are controlled by the latter.
Computer sound cards typically feature the ability to interpret MIDI files into music. Since they don't actually contain the music itself, but rather the commands used to re-create music, MIDI files are a lot smaller than audio files like MP3s, WMAs, or WAVs. MIDI files are small and manageable enough that it's not uncommon to find them embedded in web pages, adding a sonic element to the surfing experience. MIDI files usually appear with the .MID filename extension.

MP3 stands for MPEG 1, Layer III, an audio file codec standard, allowing an entire CD of audio data to be compressed for streaming transmission over the internet. MP3 is increasingly widespread in its use to transmit internet audio, to burn MP3 CD, and is currently the bête noire of the music industry, owing to the recent marketing of MP3 players (which have withstood an injunction attempt by RIAA.) With audio converter, audio maker or MP3 CD burner applications, you can convert MP3 file into other formats or burn MP3 CD.
MP3's bitrates vary from 8kbps to 320kbps. A typical MP3 file encoded at 128kbps is near CD quality. MP3 audio is increasingly being used in video production coupled with various MPEG4 video codecs like DivX.

The file extension for playlists created in some media players including Winamp. The M3U file is a text file that contains information about the location of each media file selected for the playlist.
M3U is a special type of metafile playlist that is used with MP3 files that have an .mp3 file extension. The .M3U files list one MP3 or other media file on each line, normally with full path or URL to the file. If the .M3U file is loaded to an MP3 player, the player normally plays the list of media files in the order they are listed in the playlist (unless options such as "randomize" have been selected in the MP3 player).

Vorbis is an audio compression format, comparable to other formats used to store and play digital music, but differs in that it is free, open and unpatented. The Vorbis specification is in the public domain and if freely available for commercial or noncommercial use. In Vorbis, OGG refers to the OGG Project which is an Open Source multimedia initiative, while Vorbis is the actual compression format. Xilisoft CD Ripper and OGG MP3 Converter can convert OGG to MP3 and other popular audio files.

WAV is a standard audio format for Windows operating systems, often used for storing high-quality, uncompressed sound. WAV files can contain CD-quality audio signals. However, CD-quality WAV files require relatively large amounts of memory. To reduce space requirement, you can use audio converter to convert WAV to MP3, WMA and other popular audio formats.
WAV files are probably the simplest of the common formats for storing audio samples. Unlike MPEG audio and other compressed formats, WAVs store samples "in the raw" where no pre-processing is required other that formatting of the data.
The WAV file consists of three "chunks" of information: The RIFF chunk which identifies the file as a WAV file, The FORMAT chunk which identifies parameters such as sample rate and the DATA chunk which contains the actual data (samples).

Monkey's Audio (APE) is used by Windows users mostly. It is a free lossless audio compression format with a highly competitive compression algorithm. Although software is available for Linux, Monkey's Audio is not as popular among this operating system's users. Decompression speeds of Monkey's Audio is too slow compared to other lossless audio codecs.
Monkey's Audio successfully combines traditional lossless compression tactics (linear prediction and channel coupling) and a simple Neural network. To store the output values of its prediction step it uses Range coding, which is modified to work well with more or less continuous values.
Monkey's Audio's main competitor is FLAC, which has more features than Monkey's Audio (streaming support, for example) and hardware support to its advantage, though its efficiency in compression is not as great.
Monkey's Audio is released under a "custom" license. That means that you can do pretty much anything with the source code, just don't forget to ask the author for permission.