Mp3, what exactly is an mp3?
MP3 (formally MPEG-1 Audio Layer III or MPEG-2 Audio Layer III) is an audio coding format for digital audio.
Originally defined as the third audio format of the MPEG-1 standard, it has been maintained and expanded to define additional bit rates and support more channels of audio as the third audio format of the upcoming MPEG-2 standard. A third version, known as MPEG 2.5, improved to better support lower bit rates, is commonly implemented, but is not a recognized standard.
MP3 (or mp3) as a file format generally refers to files that contain the elementary MPEG-1 data stream for audio and video, without the other complexities of the MP3 standard.
In the audio compression aspects of MP3, the most obvious standard aspect to end users (and the one best known for) is MP3 which uses lossy data compression to encode data using imprecise approximations and partial data discarding. This allows the file size to be significantly reduced compared to uncompressed audio. The combination of small size and acceptable fidelity led to a boom in music distribution over the Internet in the mid to late 1990s, as a provider technology when bandwidth and storage were still at their peak. The MP3 format was soon associated with controversy surrounding copyright infringement, music piracy, MP3.com and Napster ripping / sharing services, and others. With the advent of portable media players, a product category that includes smartphones,
MP3 compression works by reducing (or approximating) the precision of certain audio components that are believed to be superior to the hearing capacity of most people. This technique is commonly known as perceptual coding or psychoacoustic simulation. The remaining audio information is then recorded in a cost effective manner. Compared to the digital audio quality of a CD, MP3 compression can typically achieve a 75-95% reduction. For example, an MP3 encoded at a constant 128 kbps bit rate would result in a file approximately 9% the size of the original audio CD.
Also, designed as a broadcast format, broadcast segments can be lost without compromising the ability to decode subsequent segments.
MP3 was developed by Moving Picture Experts Group (MPEG) within the MPEG-1 and later MPEG-2 standards. The first audio subgroup was made up of various engineering teams from CCETT, Matsushita, Philips, Sony, AT & T-Bell Labs, Thomson-Brandt, and others. MPEG-1 Audio (MPEG-1 Part 3), which includes MPEG-1 Audio Layer I, II and III was approved as a draft of the ISO / IEC committee in 1991, finalized in 1992 and published in 1993 as ISO / IEC 11172 -3: 1993. In 1995, the opposite was published. an extension compatible with MPEG-2 Audio (MPEG-2 Part 3) with a lower bit rate and bit rate than ISO / IEC 13818-3: 1995.
Standardization
In 1991, two proposals were submitted and evaluated for the MPEG audio standard: MUSICAM (universal universal coding adapted to mask and subband multiplexing) and ASPEC (adaptive spectral perception of entropy coding). As proposed by the Dutch Philips corporation, the French research institute CCETT, and the German standards institute Broadcast Technology, MUSICAM was chosen for its simplicity and error reliability, as well as its high level of computational efficiency The MUSICAM format, based on Subband encoding became the basis for the MPEG Audio compression format, including, for example, its frame structure, header format, sample rate, etc.
Although most of the MUSICAM technologies and ideas were included in the definition of MPEG Audio Layer I and Layer II, only the filter bank and data structure based on 1152 frame samples (file format and stream-oriented bytes) of MUSICAM remained in Layer III (MP3). as part of a computationally inefficient hybrid filter bank. Under the chairmanship of Professor Musman from the University of Hannover, the edition of the standard was delivered to the Dutch Leon van de Kerhof, the German Gerhard Stoll, the Frenchman Yves-François Deri who works on levels I and II. ASPEC was a joint offering from AT&T Bell Laboratories, Thomson Consumer Electronics, Fraunhofer Society, and CNET. This ensured maximum encoding efficiency.
