What is MIDI?

MIDI (Musical Instrument Digital Interface) is a protocol, containing a set of standard commands for sound appliances interaction. Before MIDI format appeared in the end of the seventies, the industry had already had at its disposal a lot of instruments and refinement appliances, but they hadn't been connected in any way. Electronic devices manufacturers had proposed several variants of interaction, but there hadn't been any common standards. So there appeared a need to create a universal protocol for working with electronic musical instruments for replacement of controlling musical instruments with the help of analogue signals. It's reckoned that the formal date of MIDI appearance is 1982. It was developed by leading producers of electronic musical instruments Yamaha, Roland, Korg, E-mu and others. To maintain this standard there were established Japanese MIDI Standard Committee (JMSC), MIDI Manufacturers Association (MMA) and International MIDI Association (IMA). Their task was to coordinate the actions of manufacturers and users. Let us see what the MIDI format is. In its essence, within the limits of using of instruments and computer appliances, MIDI is an easy command system, containing information about a note, about the instrument and its change, turning of a pitch wheel (gradual pitch changing), the speed of keys pressing, the length of pressing and so on. And although MIDI does not contain usual audio files, it is like a copy of performer's actions, which has retained his style of performance dynamics, technical methods and so on. Every time a performer is operating control organs (pressing and releasing keys and pedals, changing regulators position), instrument is generating a respective MIDI event, which is immediately sent to MIDI file generating appliance. When recorded to data storage appliances, MIDI events are provided with time stamps, creating an original way of score presentation. As they are reproduced, initial MIDI flow is fully and identically reconstructed from these marks. After MIDI introduction musicians have obtained various advantages. One of them is a small data amount compared with audio files. It was being commonly used at the dawn of games development, when hardware capacity and physical amounts of memory did not allow operating large amounts of audio information. In those times composers of the games music were actively using synthesizers for creating music. Nowadays, this MIDI information is actively used for portable devices and mobile phones.

Another MIDI advantage is that in this standard the polyphony is initially included. All this has driven to the fact that people working in different fields of activity have been working with MIDI format for long years. In spite of the fact that the other formats for working with musical instruments have been developed recently, it is still clear that for a long time these formats will have to be MIDI-compatible. That is why there emerges a problem of converting different data formats to MIDI.

Exactly with this type of converting WIDI Recognition System is dealing with. WIDI can read original files like uncompressed wav, mp3, CD tracks and even the sound received directly from the microphone without a precursory recording it to file (real time recognition). As a result of work of WIDI program ready MIDI file is obtained. It may be used for creating arrangements, getting musical notations of compositions for individual performing and for creating melodies for mobile phones.
The task of recognition, especially musical recordings recognition, is a serious mathematical problem and has got no universal solution at the present time. Nevertheless, WIDI Recognition System includes algorithms, allowing to perform quite precisely polyphonic transcription. Moreover, a considerable number of adjustable parameters enable recognition of different musical styles, instruments and so on.