Multimedia Glossary

AAC

AAC stands for either MPEG2 Advanced Audio Coding or MPEG4 Advanced Audio Coding.

The MPEG2 audio-encoding standard of the format is not backward-compatible with MPEG1 audio. MPEG2 AAC can produce better audio quality than MP3 using less physical space for the files. MPEG4 AAC can produce better quality and smaller files than MPEG2 AAC. AAC is the audio file format used by Apple in their popular iTunes Music Store. Files may appear on your system with the ".M4A" filename extension. View Audio Converter, it can convert mp4 to mp3, converts between MP3, WAV, WMA, AAC, FALC, OGG, APE, MP4, M4A, MP2, VQF.

AC3

AC3 file, a Dolby Digital audio file, can be found as the standard audio track on Digital Versatile Discs (DVD) and High Definition Television (HDTV). This coder has been designed to take maximum advantage of human auditory masking in that it divides the audio spectrum of each channel into narrow frequency bands of different sizes optimized with respect to the frequency selectivity of human hearing. This makes it possible to sharply filter coding noise so that it is forced to stay very close in frequency to the frequency components of the audio signal being coded. By reducing or eliminating coding noise wherever there are no audio signals to mask it, the sound quality of the original signal can be subjectively preserved.

AIFF

AIFF stands for Audio Interchange File Format.

Apple Computer developed this audio file format to store high-quality audio and musical instrument information.

FLAC

FLAC stands for Free Lossless Audio Codec.

By encoding audio files with FLAC, the quality is exactly the same as the original audio file's quality is. This is exactly unlike the audio formats such as MP3 and WMA work -- these audio formats are called "lossy" and that means that when the original audio is encoded into the lossy audio format, some of the audio data is lost forever and can't be brought back by any means.

M4A

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.

M4P

M4P format is "protected AAC". It is a format of purchased music that can be listened to only through the iTunes softer or an iPod.

MIDI

MIDI stands for Musical Instrument Digital Interface.

A MIDI file doesn't contain actual audio data, but rather contains commands that let MIDI-capable synthesizers re-create a specific musical passage. The MIDI protocol has been used for years as a way for electronic musical instruments (like digital keyboards and sequencers) to communicate with each other.

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

MP3 stands for MPEG1 (or MPEG2) Audio Layer III. Too often people refer MP3 as MPEG3, which is incorrect, because such format doesn't even exist.

MP3 is a popular compression format used for audio files on computers and portable devices. It is a method to store good quality audio into small files by using psychoacoustics in order to get rid of the data from the audio that most of the humans can't hear.

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.

MP3 ID3 Tag

An MP3 ID3 Tag is information stored at the end of an MP3 file. The tag can contain information about the Title/Songname, Artist, Album, Year, Comment, and Genre in version 1 and also Track in version 1.1. A proposed Version 2 is out which would be extendable to include more information and pictures.

ID3

ID3 is a small piece of information stored physically inside the MP3 file (in the beginning or in the end of the file, depends on ID3's version). ID3 tags can contain various information about the MP3, like album name, song name, artist, original artist, genre, composer, releasing year, additional comment fields, etc.. Nowadays ID3s are de facto in audio world and they can be added to most of the audio formats and even to certain video formats in order to provide additional information of the file.

Ogg

Ogg is the umbrella for a group of several related multimedia and signal processing projects that are open source and royalty free. Development of these projects is controlled by Xiph.org.

Ogg Vorbis

Ogg Vorbis is an "open-source" digital audio compression format. like MP3, It is a "lossy" compression system, removing frequencies deemed inaudible. Both formats offer variable-bitrate encoding options, for better efficiency. But the algorithms Ogg Vorbis uses to decide which information to discard differ from those used by MP3. Proponents claim that the Ogg Vorbis format outperforms MP3, producing files that are significantly smaller than MP3s of similar sound quality (or files that sound better than similarly sized MP3s).

WAV

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.

WMA

WMA stands for Windows Media Audio.

WMA, an audio format owned by Microsoft, is a part of Microsoft's Windows Media technology, which includes Microsoft's Digital Rights Management tools, Windows Media Video encoding technology and Windows Media Audio encoding technology.

Windows Media Audio is one of today's most popular Net audio formats. Though not as popular as MP3, WMA tends to outperform MP3 in the area of sound quality, particularly with files encoded at lower bitrates like 64 or 96 Kbps. This performance advantage makes it handy for applications like portable digital audio players, where total play time is limited by a finite amount of internal memory.