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How MP3 Works

The MP3 Player is one of the most innovating systems of storing and playing music in recent times.

The big advantage with MP3 is the convenience of size and storage abilities allowing people to carry with them thousands of songs and many hours of music for their enjoyment wherever they are. In other words portability.

MP3 is currently the most powerful algorithm in a series of audio encoding standards and is also the abbreviated name for MPEG Audio Layer-3. This is a set of standards for compressing and downloading audio files from the Internet. It is also the name for a file compressed in this format.

MPEG (pronounced EHM-pehg), is an acronym for the Moving Picture Experts Group, who develop standards for digital video and digital audio compression. It was developed under the sponsorship of the Motion Picture Experts Group (MPEG) and formalized by the International Organization for Standardization (ISO). In bald terms it is a piece of software that takes data from a sound track, such as a CD and compresses it into a form that takes up considerably less memory, only one twelfth of the original in fact. There is a slight loss of quality but, for most people, this is hardly discernable.

Technically, MP3 (MPEG-1 Audio Layer-3) is a standard technology and format for compressing a sound sequence into a very small file while, at the same time, preserving the original level of sound quality when it is played. It works on a similar basis to zipping up files where repeated data is simply listed once only and then when that piece of data is required again it is simply referred to rather than relisted over and over again.

diagram -how-mp3-worksMP3 works on a similar basis. The data that composes the sound track will have a lot of repeated information on. When the mp3 file is created only one piece of each unique data is kept and after that the software simply refers to that data and its location in the sequence. Then when the mp3 file is played the software simply puts back the data it referred to in the correct sequence and you get your song back. Of course the software for compressing and retrieving that data is in the players used in your computer or I-Pod. All you need to do is press a few buttons and you are away.

Most users will find that their operating system, such as windows, has a player incorporated into their system which will play mp3 files. Winamp for PCs, iTunes for Macs and mpeg123 for Unix systems are common mp3 players. One can create a mp3 file with a program called a ripper to extract or 'lift' a track from a CD onto a hard disk. Then a program called an encoder to convert to an mp3 file.

Most people, however, simply copy someone else's mp3.

Many Windows users will find that they have a player built into their operating system. Otherwise, you can download a player from one of several popular MP3 sites. MP3 files are usually download-and-play files rather than streaming sound files that you link-and-listen-to with RealPlayer and similar products (However, streaming MP3 is possible.) Winamp (PC), iTunes(Mac), and mpeg123 (UNIX) are popular MP3 players, but there are many others. To create an MP3 file, you use a program called a ripper to get a selection from a CD onto your hard disk and another program called an encoder to convert the selection to an MP3 file. Most people, however, simply download MP3s from someone else and play them.

Although MP3 is the most used file format these days, there are other file formats that can be played on MP3 players. While most MP3 players can support multiple formats, not all players support the same formats. Here are a few of the file formats that can be played on different players:

WMA - Windows Media Audio
WAV - Waveform Audio
MIDI - Music Instrument Digital Interface
AAC - Advanced Audio Coding
Ogg Vorbis - A free, open and un-patented music format
ADPCM - Adaptive Differential Pulse Code Modulation
ASF - Advanced Streaming Format
VQF - Vector Quantization Format
ATRAC - Sony's Adaptive Transform Acoustic Coding 3M

The MP3 player is essentially a convergence of many past technologies none of which are particularly innovative but collectively have created a product for today.

The specific components may vary, but the basic parts of a typical MP3 player include:

Data port
Memory
Microprocessor
Digital signal processor (DSP)
Display
Playback controls
Audio port
Amplifier
Power supply

The player can plug into your computer's USB port, FireWire port or parallel port to transfer data.

USB-based players transfer data many times faster than those that use the parallel port. The MP3 files are saved in the player's memory, types of which include:

Internal Flash memory
CompactFlash cards
SmartMedia cards
Memory Stick
Internal microdrive

Apart from the last one, these are all solid state memory. The advantages of a solid state memory is that there are no moving parts resulting in more reliability, less skips in music due to vibrations and external influences.

Of course, in addition to storing music, the MP3 player plays music and allows the user to hear the songs played. The player pulls the song from its memory then decompresses the MP3 encoding, through DPS, via an algorithm or formula. It then runs the decompressed bytes through a digital-to-analog converter into sound waves and amplifies the analog signal, allowing the song to be heard.

All portable MP3 players are battery-powered using rechargeable internal lithium battery in most cases and will last for around 10 to 28 hours on a single charge depending on use. Some have adapters enabling them to be played while plugged into the mains or into a car socket.

Types of MP3 Player

There are many different types of MP3 Players. Which one a person selects depends primarily on how they will use it and how much memory they require. Price does factor into the choice also of course.

There are basically 4 types of MP3 player.

Flash Memory Players
The flash memory MP3 player is the smallest and lightest and typically stores fewer songs than hard drive players. Because it's small and contains no moving parts, it's ideal for exercisers. And with some models boasting up to 8 GB of storage (2,000 songs) and other models offering video and photo capability, it also appeals to the multimedia aficionado. Its batteries can last up to 28 hours.

Hard Drive and Mini-hard Drive Players
Hard drive players are larger and heavier than flash memory players and offer considerably more storage. (The Apple iPod holds up to 80GB.) For those looking for a player that can contain their entire music collection (up to 20,000 songs), photographs, data, and video and allow podcast recording, the hard drive is best. However, these features and the hard drive consume more power, with some batteries lasting eight to 20 hours for music playback and up to six hours for video playback. The players include moving parts, which may skip. However, some players have anti-shock buffers and or anti-skip protection.

Smaller in size and internal storage capacity, miniature-hard drive players are lighter than traditional hard drive players, but contain less memory -- usually up to 8 GB. They also contain moving parts.

MP3 CD Players and MiniDisc MP3 Players
There is a breed of CD players available that plays MP3 and other digital files. These MP3 files are burned to CD-R/RW discs from your old CD collection and used in the MP3 CD player. A CD can hold about 10 hours of music. A CD burner is necessary for those buying an MP3 CD player. The MP3 CD player is cheaper than the flash memory and hard drive memory players, but may skip when jostled. They are also much larger in size than their digital counterparts. For those who appreciate MiniDisc technology, there's Sony's MiniDisc Walkman digital music player. This player supports the trademark Sony file format codec ATRAC3 -- but it also supports MP3, WMA and WAV formats, too. And the multitasking doesn't stop there. Sony reports that the 1GB Hi-MD discs can also store and transfer loads of PC data files (think PowerPoint presentations, spreadsheets, et cetera). The discs retail for less than $10, store up to 600 songs and are re-recordable. Depending on the model, users can expect anywhere from 30-plus hours of playtime from just one AA battery.

The Hybrid Players
MP3 is no longer just a stand-alone technology. Technology companies are now offering MP3 capability in other consumer products, including vehicles, satellite radios, personal digital assistants, DVD players, sunglasses, swim goggles and even a combination Swiss Army Knife-MP3 player. Most notably, smart phones now cross a cell phone with an iPod and Web browser, along with a variety of other features.

Picture courtesy of How Stuff Works


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