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 Open Sound System (OSS) is the first attempt in unifying the digital audio architecture for UNIX. OSS is a set of device drivers that provide a uniform API across all the major UNIX architectures. It supports Sound Blaster or Windows Sound System compatible sound cards which can be plugged into any UNIX workstation supporting the ISA or PCI bus architecture. OSS also supports workstations with on-board digital audio hardware.

Traditionally, each UNIX vendor has provided their own API for processing digital audio. This meant that applications written to a particular UNIX audio API had to be re-written or ported, with possible loss of functionality, to another version of UNIX. Applications written to the OSS API, need to be designed once and then simply re-compiled on any supported UNIX architecture. OSS is source code compatible across all the platforms.

Most UNIX workstations, thus far, have only provided support for digital audio sampling and playback (business audio). OSS brings the world of MIDI and electronic music to the workstation environment. With the advent of streaming audio, speech recognition/generation, computer telephony, Java and other multimedia technologies, applications on UNIX can now provide the same audio capabilities as those found on Windows NT, OS/2, Windows 95 and the Macintosh operating systems. OSS also provides synchronized audio capabilities required for desktop video and animation playback.

Features

Digital Audio sampling and playback
  • 8bit unsigned and u-law
  • 16bit signed PCM data
  • A-Law and IMA ADPCM (CS4231 compatible hardware)
  • Stereo and mono sampling/playback
  • Sampling rates between 4KHz and 48 KHz
  • Half duplex and full duplex (on hardware supporting Full-duplex)
  • Support for direct access to audio DMA buffer.
    • Permits tighter timing for real time applications such as games and audio effect generators.
    • Less processing overhead since copying of data (192 kb/s in worst case) between application buffer and the DMA buffer is not required.
  • Capability to start recording and playback precisely at the same time (full duplex).
  • Capability to syncronize audio recording/playback with MIDI playback.

FM and Wave-table MIDI playback

  • Hardware independent access to MIDI features using built in synthesizer chips (FM or wave table) and MIDI synthesizers or sound modules.
  • Device independent sample/patch loading API library for synthesizers.
  • Support for SoundFont 2.0 standard (Emu/Creative)
  • Support for SMPTE, MTC and other timing standards.
MIDI input and output
  • Support for MPU-401 UART and Sound Blaster MIDI UART MIDI I/O.
  • Support for SMPTE, MTC and other timing standards.
  • Support for XG MIDI standard (Yamaha).
Mixer
  • Main, FM Synthesizer, Wave-table, Digital Audio Volume
  • Mic, CD-Input, Line-in Volume in
  • Reverb, Chorus, and other effects on SB AWE32/64
  • SRS-3D Spatial Audio on supported hardware
  • Support for S/PDIF, AES/EBU, TOSLink, XLR, etc. on PRO sound cards
Advanced Technologies
  • Virtual audio mixer - play 8 simultaneous audio streams with sample rate conversion and realtime mixing
  • Synthesizer - Software based 32voice wave-table MIDI synthesizer
  • Input Multiplexer - run up to 8 simultaneous recording applications at different sample rates , bits and channels using a single input source.

UNIX versions

Workstations

  • IBM/Motorola PowerPC (PCI/ISA bus)
  • Intel 386/486 and Pentium PCs (ISA/EISA/PCI bus)
  • SUN Sparc
  • DEC Alpha-AXP (ISA/PCI bus)

Sound cards