Mp3 Players Manufacturer

Description of our MP3 Players

1) MP3, WMA music format

2) EQ: Normal, jazz, classical, rock, popular, bass

3) Color LCD Backlight: White, Sky Blue, Pink, Blue, Yellow, Green, Red

4)Built-in voice recorder

5)Built-in FM radio( optional)

6)Multi-languages menu optional

7)Data transfer rate up to 5MB/s for Read and 4MB/s for Write

8)Multiple Operation Systems supported: Windows, Mac and Linux

9)Only Win98 or below needs driver

10) Built-in Lithium battery

11) USB 2.0 high speed interface

MPEG-1 Audio Layer 3

MPEG-1 Audio Layer 3, more commonly referred to as MP3, is a digital audio encoding format using a form of lossy data compression. It is a common audio format for consumer audio storage, as well as a de facto standard encoding for the transfer and playback of music on digital audio players. MP3 is an audio-specific format that was designed by the Motion Pictures Expert Group. The group was formed by several teams of engineers at Fraunhofer IIS in Erlangen, Germany, AT&T-Bell Labs in Murray Hill, NJ, USA, Thomson-Brandt, and CCETT as well as others. It was approved as an ISO/IEC standard in 1991.

The use in MP3 of a lossy compression algorithm is designed to greatly reduce the amount of data required to represent the audio recording and still sound like a faithful reproduction of the original uncompressed audio for most listeners, but is not considered high fidelity audio by audiophiles. An MP3 file that is created using the mid-range bit rate setting of 128 kbit/s will result in a file that is typically about 1/10th the size of the CD file created from the original audio source. An MP3 file can also be constructed at higher or lower bit rates, with higher or lower resulting quality. The compression works by reducing accuracy of certain parts of sound that are deemed beyond the auditory resolution ability of most people. This method is commonly referred to as perceptual coding.[1] It internally provides a representation of sound within a short term time/frequency analysis window, by using psychoacoustic models to discard or reduce precision of components less audible to human hearing, and recording the remaining information in an efficient manner. This is relatively similar to the principles used by JPEG, an image compression format.

Common audio formats

MP3 is the dominant format, and is nearly universally supported.[12] The main alternative formats are AAC and WMA. Unlike MP3, these formats support DRM restrictions that are often implemented into files from paid download services. Open source formats, which are completely patent-free, are available - though less widely supported. Examples include Ogg Vorbis, FLAC, and Speex. Finally, a recent newcomer is MPEG 4, which is quickly starting to receive adoption by several digital audio players.

History of MP3

The term MP3 is actually a reference shortened from the official M(oving) P(icture) E(xperts) G(roup) -1 Audio Layer 3 nomenclature for this lossy digital audio encoding format.

The MP3 audio data compression lossy data compression algorithm takes advantage of a audio perceptual limitation of human hearing called auditory masking. In 1984, Mayer reported that a tone could be rendered inaudible by another tone of lower frequency.[2] In 1959, Richard Ehmer described a complete set of auditory curves regarding this phenomenon.[3] Ernst Terhardt et al. created an algorithm describing auditory masking with high accuracy.

In 1983, at the University of Buenos Aires, Oscar Bonello started developing a PC audio card based on bit compression technology. In 1989 he introduced the first working device based on a PC audio card using auditory masking: Audicom.

The psychoacoustic masking codec was first proposed in 1979, apparently independently, by Manfred R. Schroeder, et al..from AT&T-Bell Labs in Murray Hill, NJ, and M. A.Krasner[7] both in the United States. Krasner was the first to publish and to produce hardware for speech, not usable as music bit compression, but the publication of his results as a relatively obscure Lincoln Laboratory Technical Report did not immediately influence the mainstream of psychoacoustic codec development. Manfred Schroeder was already a well-known and revered figure in the worldwide community of acoustical and electrical engineers, and his paper had influence in acoustic and source-coding (audio data compression) research. Both Krasner and Schroeder built upon the work performed by Eberhard F. Zwicker in the areas of tuning and masking of critical bands,[8][9] that in turn built on the fundamental research in the area from Bell Labs of Harvey Fletcher and his collaborators.[10] A wide variety of (mostly perceptual) audio compression algorithms were reported in IEEE's refereed Journal on Selected Areas in Communications.[11] That journal reported in February 1988 on a wide range of established, working audio bit compression technologies, some of them using auditory masking as part of their fundamental design, and several showing real-time hardware implementations aimed at laboratory experiences. This hardware was never used in PC audio cards.

The immediate predecessors of MP3 were "Optimum Coding in the Frequency Domain" (OCF),[12] and Perceptual Transform Coding (PXFM).[13] These two codecs, along with block-switching contributions from Thomson-Brandt, were merged into a codec called ASPEC, which was submitted to MPEG, and which won the quality competition, but that was mistakenly rejected as too complex to implement. The first practical implementation of an audio perceptual coder (OCF) in hardware (Krasner's hardware was too cumbersome and slow for practical use), was an implementation of a psychoacoustic transform coder based on Motorola 56000 DSP chips. MP3 is directly descended from OCF and PXFM. MP3 represents the outcome of the collaboration of Dr. Karlheinz Brandenburg , working as a postdoc at AT&T-Bell Labs with Mr. James D. Johnston of AT&T-Bell Labs, collaborating with the Fraunhofer Society for Integrated Circuits, Erlangen, with relatively minor contributions from the MP2 branch of psychoacoustic sub-band coders.

MPEG-1 Audio Layer 2 encoding began as the Digital Audio Broadcast (DAB) project managed by Egon Meier-Engelen of the Deutsche Forschungs- und Versuchsanstalt für Luft- und Raumfahrt (later on called Deutsches Zentrum für Luft- und Raumfahrt, German Aerospace Center) in Germany. The European Community financed this project, commonly known as EU-147, from 1987 to 1994 as a part of the EUREKA research program.

As a doctoral student at Germany's University of Erlangen-Nuremberg, Karlheinz Brandenburg began working on digital music compression in the early 1980s, focusing on how people perceive music. He completed his doctoral work in 1989 and became an assistant professor at Erlangen-Nuremberg. While there, he continued to work on music compression with scientists at the Fraunhofer Society (in 1993 he joined the staff of the Fraunhofer Institute).

In 1991 there were two proposals available: Musicam and ASPEC - (Short excerpt on German Wikipedia) (Adaptive Spectral Perceptual Entropy Coding). The Musicam technique, as proposed by Philips (The Netherlands), CCETT (France) and Institut für Rundfunktechnik (Germany) was chosen due to its simplicity and error robustness, as well as its low computational power associated with the encoding of high quality compressed audio.[15] The Musicam format, based on sub-band coding, was the basis of the MPEG Audio compression format (sampling rates, structure of frames, headers, number of samples per frame). Much of its technology and ideas were incorporated into the definition of ISO MPEG Audio Layer I and Layer II and the filter bank alone into Layer III (MP3) format as part of the computationally inefficient hybrid filter bank. Under the chairmanship of Professor Musmann (University of Hannover) the editing of the standard was made under the responsibilities of Leon van de Kerkhof (Layer I) and Gerhard Stoll (Layer II).