Java Sound Technology detailed

Sound can create a mood, triggering reverie, when combined with virtual images, more can let the whole world full of illusion. Sound is the basis of multimedia technology. This is why Sun's Java Media technology development team is busy preparing the Java Sound 1.0 API and including it in the next version of the Java Development Tool Library.

Before the advent of the JAVA2 platform, the Java language was able to handle only the sound of telephone sounds, which were stored as μ-law au files at a single channel 8KHZ sampling frequency. The JAVA2 platform adds support for Aiff,wav and three of MIDI file types. The three MIDI file formats supported are MIDI file type 0, midi file type 1, and RMF.

The API1.0 version of the application interface provides an Easy-to-use toolset that enables programmers to access the underlying compositing and performance engine, extending the application of Java sounds. One of the two important areas is the creation of digital audio and musical instrument instruction Digital Interface midi. As a result of providing a large number of low-level support functions, programmers can input output voice, control MIDI devices, and can query the operation of the system.

Introduction to sound file types

The main sound file types are as follows:

Au-(extension au or snd) is suitable for short sound files, a common file format for Solaris and next-generation machines, and a standard audio format for the Java platform. The three typical audio formats used by the AU type file are: 8-bit Μ-law type (usually the sample frequency is 8kHz), 8-bit linear type, and 16-bit linear type.

WAV-(extension WAV) is developed jointly by Microsoft and IBM, and support for WAV has been added to Windows 95 and extended to Windows 98. WAV files can store various formats including Μ-law,a-law and PCM (linear) data. They can be played almost by all Windows applications that support sound.

AIFF-(extension is either AIF or IEF) The audio Interchange file format is a standard audio file format that is common to Macintosh computers and Silicon Graphics (SGI) computers. AIFF and aiff-c are almost identical except that the latter supports compression of types such as Μ-law and IMA ADPCM.

Midi-(mid-extended) musical Instrument Digital Interface MIDI is a standard recognized for the music industry, and is used primarily to control devices such as synthesizers and sound cards.

MIDI files do not contain digital audio sampling, but instead include a series of instructions that control the composition of notes from different instruments. Some MIDI files contain additional instructions to program the various compositing settings.

Most synthesizers support MIDI standards, so music made on one synthesizer can play on the other. A computer with a MIDI interface can manipulate MIDI data to produce new music or sound effects. For example, a complete piece of music can be transformed into a new form by a software-driven command.

The Java sound engine supports two types of MIDI files:

MIDI type 0 Files-contains only one sequence, and all related musical instruments are partially included on the same logical "track".

MIDI Type 1 Files-contains multiple "tracks" that allow different instruments to be logically separated, making it easier to manipulate and reorganize sounds.

RMF-(extension RMF) Mixed music format is a mixed file type designed by Beatnik, which encapsulates MIDI and audio samples with interactive settings. RMF is like a container for all the music-related files. RMF also contains support for the detailed documentation of copyright. The RMF file can contain multiple works that are stored as MIDI types or audio sampling types authored by different artists, each associated with related copyright information.

The choice of sound engine

In 1997, Sun's Java Media Development team tried to find a way to enhance the processing power of sound and provide a solid platform for the future. According to Michael Bundschuh, manager of the Java Media Development Group, "We want a very high quality playback engine to handle every operation from the eight-bit μ-law level to the sound of CD quality." We want to easily cross all platforms, such as the Solaris platform, Windows, Mac, and more. We also want a highly developed MIDI capability that spans different platforms. For the above purposes, the reasonable choice is Beatnik's audio engine (formerly headspace. )"

Sun obtained Beatnik's audio engine license and used it as the basis for the Java Sound Application interface API.

Introduction to Thomas Dolby Robertson-beatnik

Before the early 90, Thomas Dolby Robertson's career was entirely musical. "She lit me up with science" was an early MTV masterpiece, his 1982 launch. Throughout the 80 's, he was constantly composing and recording, using an unstructured music-making software. But in 1990, through a demonstration of virtual reality for the Guggenheim Museum, he began to think about whether he could do something to improve his music-making abilities.

"I was on the C Programmer's shoulders, and I suddenly realized that I was doing a lot of work for the record, but I didn't do anything to interact with the player," he said. With that in mind, Robertson established headspace in 1992 to hire a moonlight composer to help achieve his point of view. Headspace became a company in 1996 and is now known as beatnik.