Tuesday, February 26

how does an mp3 player works??

The MP3 player is the most recent in an evolution of music formats that have helped consumers enjoy their tunes. Records, 8-track tapes, cassette tapes and CDs -- none of these earlier music formats provide the convenience and control that MP3 players deliver. With an MP3 player in hand or pocket, a consumer can create personalized music lists and carry thousands of songs wherever they go.

MP3 File Format:- The MP3 file format revolutionized music distribution in the late 1990s, when file-swapping services and the first portable MP3 players made their debut. MP3, or MPEG Audio Layer III, is one method for compressing audio files. MPEG is the acronym for Moving Picture Experts Group, a group that has developed compression systems for video data, including that for DVD movies, HDTV broadcasts and digital satellite systems. Using the MP3 compression system reduces the number of bytes in a song, while retaining sound that is near CD-quality. Anytime you compress a song, you will lose some of its quality, which is the trade-off for the ability to carry more music files in a smaller storage system. 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 3






The Technology:-

Unlike earlier forms of music players that required moving parts to read encoded data on a tape or CD, MP3 players use solid-state memory. An MP3 player is no more than a data-storage device with an embedded software application that allows users to transfer MP3 files to the player. MP3 players also include utilities for copying music from the radio, CDs, radio or Web sites and the ability to organize and create custom lists of songs in the order you want to hear them. This list of songs is called a playlist.

The MP3 player is the convergence of many technol
ogies. Alone, none of its components are revolutionary, but together they create an unprecedented consumer product.

Specific components may vary, but here are the basic parts of 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 With the exception of the last one, these are all types of solid-state memory. The advantage to solid-state memory is that there are no moving parts, which means better reliability and no skips in the music. MP3 players that contain tiny hard disk drives can store 10 to 150 times more than Flash memory devices can. 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. In addition to storing music, the MP3 player must play music and allow the user to hear the songs played. To do this, the player: * Pulls the song from its memory. * Decompresses the MP3 encoding, through DPS, via an algorithm or formula. * Runs the decompressed bytes through a digital-to-analog converter into sound waves. * Amplifies the analog signal, allowing the song to be heard. All of the portable MP3 players are battery-powered. Most use a rechargeable internal lithium battery and last for approximately 10 to 28 hours on a single charge. Many of the players also have AC adapters so they can be plugged into a normal electrical outlet, and some even offer DC adapters for use in a car.


Types of MP3 Players:-
MP3 players are as varied as the people who buy them. Choice is based on several factors, including how you plan to use it, the amount of music you want to carry in your MP3 player and how much you are prepared to pay. Let's take a look at the four basic types of MP3 players.
The Apple iPhone is an example of a flash drive. Courtesy Consumer Guide Products The Apple iPhone has a 4 GB or 8 GB flash drive.

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:
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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, too, 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. Myvu video goggles connect to an iPod and project sound and “floating video images.” Photo courtesy Damien Dovarganes/ Associated Press Myvu video goggles connect to an iPod and project sound and “floating video images.” 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 satellite radios, personal digital assistants, DVD players, sunglasses, swim goggles and even a combination Swiss Army Knife-MP3 player. Most notably, the iPhone from Apple crosses a cell phone with an iPod and Web browser, along with a variety of other features.

Sunday, February 24

FiReWiRe---cOmPlEtE iNfo....

FireWire is Apple Inc.'s brand name for the IEEE 1394 interface (although the 1394 standard also defines a backplane interface). It is also known as i.LINK (Sony's name) and DV (Panasonic's name, not to be confused with DV camcorder tapes). It is a serial bus interface standard, for high-speed communications and isochronous real-time data transfer, frequently used in a personal computer (and digital audio/digital video).

FireWire has replaced Parallel SCSI in many applications, due to lower implementation costs and a simplified, more adaptable cabling system. IEEE 1394 has been adopted as the High Definition Audio-Video Network Alliance (HANA) standard connection interface for A/V (audio/visual) component communication and control[1]. FireWire is also available in wireless, fiber optic, and coaxial versions using the isochronous protocols. Wireless FireWire is being integrated into the WiMedia Alliance's WiMedia Ultra-Wideband (UWB) standard.


Almost all modern digital camcorders have included this connection since 1995. Since 2003 many computers intended for home or professional audio/video use have built-in FireWire/i.LINK ports, including all Sony computers, all but one of Apple's computers, and most Dell and HP models currently produced. It is also available on many retail motherboards for do-it-yourself PCs.





Technical specifications

FireWire can connect up to 63 peripherals in a tree topology (as opposed to Parallel SCSI's Electrical bus topology). It allows peer-to -peer device communication — such as communication between a scanner and a printer — to take place without using system memory or the CPU. FireWire also supports multiple hosts per bus. It is designed to support Plug-and-play and hot swapping. Its six-wire cable is more flexible than most Parallel SCSI cables and can supply up to 45 watts of power per port at up to 30 volts, allowing moderate-consumption devices to operate without a separate power supply. (As noted earlier, the Sony-branded i.LINK usually omits t he power wiring of the cables and uses a 4-pin connector. Devices have to get their power by other means.)

FireWire devices implement the ISO/IEC 13213 "configuration ROM" model for device configuration and identification, to provide plug-and-play capability. All FireWire devices are identified by an IEEE EUI-64 unique identifier (an extension of the 48-bit
Ethernet MAC address format) in addition to well-known codes indicating the type of device and the protocols it supports.

Operating system support

Full support for IEEE 1394a and 1394b is available for FreeBSD, Linux, Apple Mac OS 8.6 through to Mac OS 9[5], and Mac OS X as well as NetBSD and Haiku. Microsoft Windows XP supports both, but as of Service Pack 2, each FireWire device will run at S100 (100 Mbit/second) speed. A download is available from Microsoft which enables devices rated at S400 or S800 speeds to operate at their rated speed.[6] Some FireWire hardware manufacturers also provide custom device drivers which replace the Microsoft OHCI host adapter driver stack, enabling S800-capable devices to run at full 800 Mbit/s transfer rates. Microsoft Windows Vista currently supports only 1394a, with 1394b support coming later in a service pack. (Vista SP1 RC1 is available from mid December 2007, with full release expected during the first quarter of 2008)



Comparison to USB

Although high-speed USB 2.0 runs at a higher signaling rate (480 Mbit/s) than FireWire 400, typical USB PC-hosts rarely exceed sustained transfers of 35 MB/s (280 Mb/s), with 30 MB/s (240 Mb/s) being more typical (the theoretical limit for a USB 2 high-speed bulk transfer is 53.125 MB/s). This is likely due to USB's reliance on the host-processor to manage low-level USB protocol, whereas FireWire automates the same tasks in the interface hardware. For example, the FireWire host interface supports memory-mapped devices, which allows high-level protocols to run without loading the host CPU with interrupts and buffer-copy operations.[13]

FireWire 800 is substantially faster than Hi-Speed USB.

Sunday, February 17

Computer Speakers...know More.

Computer Speakers...know More.



Adding speakers to your computer can increase its functionality and enriches the experience of using it. Computer speakers are functional devices that are attached to the computer and are very much useful for recreation as well as other activities. These not only produce the most exciting sound but also are capable of bringing music, movies or games to life.

In today's scenario where we can find all sorts of multimedia applications, games and MP3 music, it is very hard to imagine a computer without speakers. They have become essential for any computer so that it can be used for all the applications. With time these have seen many changes and are getting better. We can find them for all applications and budgets.

The most popular type of speakers available today are standard, multi-channel surround sound, and USB speakers. Lets learn more about them.

Standard Speakers

Most popular of the lot that can be found easily in most of the households. The standard speakers are normal 2.1 channel or 2 channel output which include a subwoofer in the 2.1 channel version. These produce enough sound required by a home or corporate user. On the price band, these are considered cheap and easily installable with lesser wiring compared to the multi channel models.

Multi-channel Speakers

More advanced is the multi-channel version that can deliver a surround sound effect. In the multi-channel model the channels refer to the output of the device. For instance The 5.1 channel surround sound system means a 5 speaker and one subwoofer included in it which delivers superior sound quality and can bring any PC game or movie to life. These new generation models are exceptional on sound quality but comparatively costly than the standard versions.

USB speakers

Considering the portability issues you will also find USB models that are powered from the 5 volts at a few milliamps provided by the USB port, per the standard. In such speakers, the USB powered amplifier draws the power through a USB cable/plug. For the USB version no batteries or AC power source is required.

Considering your application need and budget you can decide on the type you want to buy. Pro's can opt for multi-channel speakers that allow sound/video editing or gaming in real time delivering the best sound output. For budget conscious these are the best options as they deliver a handsome sound quality and save you money on the device as well as on its installation.

If budget is not a constraint a 5.1 channel surround sound system is the best buy but also has some drawbacks like wiring and high cost. A 2.1 system with 2 speakers and a subwoofer is a decent alternative if compared to the above. Even the 2 would be a great idea for limited sound quality and budget.