| FILE FORMATSThere are several audio file | | | | Media Audio A digital system invented by |
| formats in common use. There are fewer video | | | | Microsoft, and is used in portable digital |
| file formats, but audio video file extensions | | | | audio players. Using WMA, a file can be |
| can be confusing. This is just a brief | | | | programmed so that it cannot be copied, and |
| description of what the more commonly used | | | | can be used to protect copyright.WMF: Windows |
| audio and video file formats and systems | | | | Media Format These are audio-video files |
| are.AAC:Advanced Audio Coding This is the | | | | comprising WMA and video codecs. They provide |
| audio file format used by Apple for the | | | | high quality and media security for streaming |
| iTunes Music Store, and it may appear with | | | | and download and play applications on |
| the M4A filename extension. It is better than | | | | computers.WMV: Windows Media Video Used in |
| MP3 for sound quality. It was developed as | | | | the Windows media Player, this is used to |
| part of the MPEG4 group owned by Dolby (see | | | | stream and download and play audio and video |
| below).AU: This audio file format is the | | | | content.When dealing with audio and video |
| standard used by Java, Sun and Unix.MPEG: | | | | file formats, you will sometimes notice the |
| Moving Pictures Expert Group There are a | | | | term 'codec'. A codec is simply short for |
| number of MPEG types now, described | | | | encoder-decoder (or compressor - |
| below.MPEG-1: This is used in digital cameras | | | | decompressor). A main function of a codec is |
| and camcorders for small video clips. VHS | | | | to compress audio or video data streams so |
| quality playback can be expected from | | | | that transmission of digital audio samples |
| MPEG-1.MPEG-2: Used for digital satellite TV, | | | | and video frames can be speeded up and |
| professional movie recording and recording of | | | | storage space reduced.The objective of all |
| home DVD recordings. Provides provision for | | | | codecs is to reduce the file size to a |
| multi-channel surround sound | | | | minimum while maintaining audio and video |
| recordings.MPEG-3: MPEG-3 was propose as an | | | | quality. A quick indication of the codec's |
| entity, but eventually merged into | | | | place in the path of transmission and |
| MPEG-2.MPEG-4: This is the newest MPEG system | | | | reception is:Video device (e.g. camcorder) - |
| and is used for streaming internet content. | | | | video capture card - video digitized - codec |
| It is also used in portable video recorders | | | | (compresses digital info) - result (MPEG2, |
| and for internet downloads. Required for | | | | AVI, WMV etc) - codec (decompress) - video |
| DivX. It improves digital broadcasting and | | | | frames - display device.Between the two |
| interactive graphics and multimedia.MP3: | | | | codecs the compressed result is transferred |
| Digital audio files, most commonly used to | | | | to the display device transmitted, stored on |
| store and playback music. It compresses the | | | | file, etc). So to condense the flow even |
| files to about 10% of a normal audio file, | | | | further, we could basically describe it |
| and a normal music track will be about 5 -6 | | | | as:raw data - codec - transmit - codec - |
| MB in size. MP3 stands for MPEG-1 Audio Layer | | | | playThis is simplistic, but it shows where |
| 3, not MPEG-3 as many people think. A typical | | | | the codecs are used. Therefore, in order to |
| MP3 audio file is near CD quality.OGG: An | | | | play a movie, video or piece of music of a |
| audio file format supporting a variety of | | | | certain format, you need a codec in your |
| codecs, the most popular of which is the | | | | computer to allow you to decompress the file |
| audio codec Vorbis. However, MP3 files are | | | | and play it.Here is some free software which |
| much more broadly supported than Vorbis.RA: | | | | checks what codec a video system uses, and |
| Real Audio This format is designed for | | | | what codec your system needs to play it:Codec |
| streaming audio over the Internet. It is a | | | | Tool.The different video file formats are |
| self-contained file format with all the audio | | | | required to meet the requirements of various |
| information stored within the file | | | | video devices. Similarly, audio file formats |
| itself.WAV: The simplest of the audio file | | | | are designed to meet the needs of the |
| formats, developed by Microsoft and IBM, and | | | | specific delivery methods and storage and |
| built into Windows 95. It is an uncompressed | | | | playback devices introduced by large |
| audio file format with large file sizes (10 x | | | | corporations such as Microsoft, Sony and |
| MP3), and does not need further processing to | | | | Apple. Thus, Sony invented the UMD (Universal |
| play. The WAV file consists of three blocks | | | | Media Disk) for the PSP (Playstation |
| of information: The RIFF block which | | | | Portable), and Apple introduced AAC (M4A) for |
| identifies the file as a WAV file, The FORMAT | | | | its iPod.Peter Nisbet is the author of many |
| block which identifies parameters such as | | | | articles on audio and video file systems, |
| sample rate and the DATA block which contains | | | | their transmission, playback and conversion. |
| the actual data, or music sample.WMA: Windows | | | | |