THE FORMAT
The MP3 format is a compression system for music. This format helps to reduce the number of bytes in a song, without hurting the quality of the song's sound. The goal of the MP3 format is to compress a CD-quality song by a factor of 10 to 14, without losing the CD sound quality. A 32-megabyte (MB) song on a CD compresses down to about 3 MB on MP3. This lets you download a song in minutes rather than hours, and you can store 10 to 20 songs on an MP3 player using a relatively small amount of memory.
The MP3 player is a wonderful example of a new use of existing technologies. None of the components in a typical MP3 player is radical, or even new, technology. By simply combining these components in a new way, and writing some code to control it all, manufacturers have created an entirely new line of consumer products!
The job of the MP3 player is pretty straightforward. When you play a song, the player must:
1. Pull the song from memory byte by byte
2. Decompress the MP3 encoding
3. Run the decompressed bytes through a digital-to-analog converter
4. Amplify the analog signal so you can hear it
The main difference between a portable CD player and an MP3 player is that the CD contains the bytes instead of memory, and on a CD the bytes are already decompressed so no decompression is needed.
PARTS OF THE PLAYER
Let's take a look at the components that make up a typical MP3 player:
Data port
Memory
Microprocessor
Digital signal processor (DSP)
Display
Playback controls
Audio port
Amplifier
Power supply
The player plugs 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.
Memory types include:
Internal Flash memory
CompactFlash cards
SmartMedia cards
Memory Stick
Internal microdrive
Iomega PocketZip removable media
With the exception of the last two, these are all types of solid state memory. The advantage to solid state memory is that there are no moving parts; and no moving parts means better reliability and no skips in the music.
The microprocessor is the brains of the player. It monitors user input through the playback controls, displays information about the current song on the LCD panel and sends directions to the DSP chip that tells it exactly how to process the audio.
The DSP pulls the song data from memory, applies any special effects, or EQ, and streams it to the amplifier. The DSP runs a decompression algorithm that undoes the compression of the MP3 file and then a digital-to-analog converter turns the bytes back into waves (see How Analog and Digital Recording Works for details).
The amplifier boosts the strength of the signal and sends it to the audio port, where a pair of headphones or ear buds are connected
THE FUNCTIONS
The MP3 format is a compression system for digital music that helps reduce the size of a digitized song without hurting the sound quality. Digital music is converted to MP3 format and made available for individual use, usually on the Web. You can download MP3 files from the Internet using your computer and special software, either commercial or freeware. You can also convert digital music from a CD into MP3 format using your computer and commercial or free software.
You can play MP3 files in three different ways:
You can play them directly on a personal computer
You can decompress an MP3 file and record it onto a CD
You can play MP3 files on a portable MP3 player. (Note: here we are referring to "MP3 player" as the device, rather than the software used to play the MP3 file on a desktop or laptop computer.)
The advantage of MP3 players is that they are small, lightweight and rugged. They are a great way to carry your MP3 files with you!
Hope that explains somethings....
