GoJiTa972 a écrit:
Les gars, faîtes attention avant de poster des conclusions hâtives. Ce sont bien des chercheurs de Philips, en collaboration avec d'autres, qui ont inventé le format. Par contre, le brevet est actuellement détenu par Thomson, qui a des accords avec ou des parts dans l'institut Fraunhofer, à l'origine du projet.
Non, justement... Philips n'a rien à voir avec le MP3 :
http://www.mp3licensing.com/mp3/history.html
The History of mp3
Early 1970s: Prof. Dieter Seitzer of Erlangen-Nuremberg University in Germany begins wrestling with the problem of compressing music over phone lines. Initially refused research money to pursue the goal, he establishes a group of technicians and scientists interested in audio coding research to tackle the problem
1979: Prof. Seitzer's team develops a first digital signal processor capable of audio compression. During subsequent development, a student of Prof. Seitzer, Karlheinz Brandenburg, developed and enhanced basic principles for perceptual audio coding exploiting the hearing properties of the human ear as described in psychoacoustics. Under Seitzer's guidance, Brandenburg and the team continuously developed a number of coding algorithms.
1987: In 1987 a research alliance is formed between Erlangen-Nuremberg University and the Fraunhofer Institute for Integrated Circuits within the framework of the European Union-funded EUREKA project EU147 for Digital Audio Broadcasting (DAB). Led by Fraunhofer's Prof. Heinz Gerhaeuser, the joint research project takes an important next step. With the LC-ATC (Low Complexity Adaptive Transform Coding) algorithm as the basis for its research, the joint venture began building a working real-time codec using multiple digital signal processors (DSPs). The hardware system, based on multiple DSP modules and a number of audio and data I/O interface cards, was developed from scratch by a team of scientists that included Harald Popp and Ernst Eberlein. Until now LC-ATC existed only as a simulation on minicomputers and could be tested only with very limited amount of audio material (a few audio excerpts) due to the high computation time needed. The real-time codec would enable testing of LC-ATC under real-world conditions and allow for significant additional algorithmic optimizations.
1989: Brandenburg finishes his doctoral thesis on the OCF (Optimum Coding in (the) Frequency Domain) algorithm, described by Fraunhofer as exhibiting "many of characteristics of the eventual MP3 coder, including a high frequency resolution filterbank, non-uniform quantization, Huffman coding, and side information structure." Fraunhofer contends that "the OCF coder is considered a breakthrough at that time and is a precursor of MP3." OCF scanned and removed sound below or above the threshold for human hearing. The software part of the real-time system for OCF was mainly driven by Bernhard Grill under the lead of Gerhaeuser.
1991: Incorporating contributions by Hannover University, AT&T, and Thomson, the Fraunhofer team improved the OCF algorithm which yields a powerful new audio codec called ASPEC (Adaptive Spectral Perceptual Entropy Coding). ASPEC was proposed for the forthcoming MPEG audio standard which started in 1988. MPEG in total received 14 proposals and encouraged the participants to merge their contributions, ending in four proposals which included ASPEC and MUSICAM. After formal tests MPEG encouraged MUSICAM and ASPEC to merge to create a family of three coding schemes, where Layer I was a low complexity variant of MUSICAM, Layer II was a optimized version of MUSICAM and Layer III was mainly based on ASPEC. Due to its lower complexity, DAB selected Layer II as the audio format for its digital audio broadcasting services. Although Fraunhofer's ASPEC complexity was higher, the codec provided the highest coding efficiency and therefore was the key to transmit high quality audio via ISDN phone lines. As proof of concept, Fraunhofer manufactured and sold a small number of the ASPEC studio equipment (19" racks) to professional users such as several radio stations. As a first application it was successfully used to transmit music reliably via ISDN between broadcasting studios.
The evolution from ASPEC to the final MP3 (MPEG-1, Layer 3) codec included some technological harmonizations with the other planned MPEG-1 audio coders (such as MPEG-1, Layer 2's polyphasefilterbank) and the addition of joint stereo coding, which allows the coder to not only perform well on monophonic signals but also to efficiently handle stereo material. The latter was developed by Juergen Herre for MP3.
1992: The Moving Picture Experts Group (MPEG), the ISO (International Organization of Standardization) working group charged with developing compressed digital audio and video standards, concludes a first compression standard called MPEG-1 for use in video CDs (CD-I) . In its audio section, a generic family of three codec formats (Layer-1, -2, -3) is specified. Layer 3 is a more efficient codec and leads to its widespread adoption as a way to store music on the relatively small hard disk drives of the era's PCs and to transfer music files over the Internet through pokey 28.8kbps PC modems.
1995: MP3 gets its name. In an internal poll, Fraunhofer researchers unanimously vote for .mp3 as the file-name extension for MPEG Layer 3. MPEG Layer-3 is also selected as the audio format for the WorldSpace satellite digital audio broadcasting system.
1998: The era of MP3 portability began with the introduction of Diamond Multimedia's Rio in the U.S. and Saehan Information Systems's MPMAN in Korea. They are the first headphone stereos that used solid-state flash memory to store and play compressed MP3 music files, either downloaded from the Internet or "ripped" from a music CD. The ensuing popularity of MP3 portables led dozens of companies to offer compressed-music portables, and it led to the development of additional audio codecs for use in PCs and in portable devices.
2000: In the U.S., suppliers launch the first headphone stereos equipped with hard drives and the first headphone CD players that play MP3-encoded 5-inch CDs.
Since that time, mp3 has become a cultural phenomenon, with hundreds of millions of computers and consumer electronic devices sold that include mp3 capability.
The ability to store thousands of songs on a small portable player, search them by Album, Artist, Title, Genre, or even have play lists generated automatically, has reawakened millions of people's love for music. You no longer have to find a misplaced CD to hear a song you haven't heard for years. Your whole collection is now available at the press of a button. In fact, inexpensive 40GB mp3 players can hold over 16,000 CD quality songs, ready for immediate play, wherever you are - at home, at the beach, in your car, in the train, on the plane.
mp3 is more than a technology. It is a sensational development that has reconnected musicians to music lovers, speakers to their listeners, creators to their audience.
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