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There are several audio and video data file formats recognized by common audio video application.
This article is just a brief description of what the very commonly used audio and video file formats.

AAC
Advanced Audio Coding. This is the audio file format utilized by Apple for their iTunes Music Store, and it may appear with the M4A extension. The sound quality is much better than MP3. It was prepared as part of the MPEG4 group owned by Dolby (see below).

AU
This audio file format is the common utilized by Java, Sun and Unix.

MPEG
Moving Pictures Expert Group. Presently, there are numerous MPEG types. They are all described below.

MPEG-1
This data format is utilized in digital cameras and camcorders for small video recording. VHS quality playback can be expected from MPEG-1.

MPEG-2
Used for digital satellite Television, professional film recording and make personal DVD recordings. Provides provision for multi-channel surround sound recordings.

MPEG-3
MPEG-3 was offered as a different formats, but eventually combined into MPEG-2.

MPEG-4
This is the newest MPEG system and is utilized for streaming cyberspace content. It is also used in camcorder and for internet downloads. Required for DivX, it improves digital circulating, interactive graphics and multimedia.

MP3
Digital audio files, most commonly utilized to save and playback music. It compresses the files to nearly ten percent of a typical audio file, and a regular music track is around 5 – 6 MB. MP3 stands for MPEG-1 Audio Layer 3, not MPEG-3 as many people think of. A regular MP3 audio file is near to CD quality.

OGG
An audio file format support a variety of codecs, the well known audio codec is Vorbis. Yet, MP3 files are even more supported than Vorbis.

RA
Real Audio. This format is planned for streaming audio through the Internet. It is a self-contained file format with complete audio information kept within the file itself.

WAV
The most simple audio file formats, improved by Microsoft and IBM, and built together with Windows 95. It is an uncompressed audio file format, that is why this data format has large file size (10 x MP3), and does not need further processing to play. The WAV data format consists of three blocks of information. The RIFF block which identifies the file as a WAV file, The FORMAT block which describes parametric quantities such as sampling value and the DATA block which carries the actual information, or music sampling.

WMA
Windows Media Audio. A digital system manufactured by Microsoft, and is used in portable digital audio players. Using WMA, a file can be protected so that it cannot be replicated, and it can also be used to protect copyright.

WMF
Windows Media Format. These are audio-video files consisting of WMA and video codecs. They supply high quality and media protection for streaming, downloading and playing applications on computers.

WMV
Windows Media Video. Used in the Windows Media Player, this is used to stream, download and play audio and video content.

When handling audio and video file formats, sometimes you will notice the term ‘codec’. A codec is the acronym for encoder-decoder or compressor – decompressor. A primary function of a codec is to compress audio or video data flows so that the process of transmitting digital audio sample and video frames can be speeded up and reduce storage space.

The target of most codecs is to reduce the file size to the smallest while keeping audio and video quality.
A fast indication of the codec’s position in the track of transmission and reception is:
Video device (e.g. camcorder) – video capture card – video digitized – codec (compresses digital info) – result (MPEG2, AVI, WMV etc) – codec (decompress) – video frames – display device.

Between the two codecs, the compressed result is transported to the display device then transmitted, stored on file, etc. So, to condense the flow even further, we could essentially identify it as:
raw data – codec – transmit – codec – play

This description is simple, but it shows up where the codecs are used. Thus, in order to play a movie, video or music of a particular format, you need a codec in your PC to allow you decompressing the file and playing it.