Audio Stream Input/Output

Audio Stream Input/Output (ASIO) is a computer soundcard driver protocol for digital audio specified by Steinberg, providing a low-latency and high fidelity interface between a software application and a computer's sound card. Whereas Microsoft’s DirectSound is commonly used as a stereo input and output for non-professional users, ASIO allows musicians and sound engineers to process their audio via Windows computer software instead of external hardware.

ASIO bypasses the normal audio path from the user application through layers of intermediary Windows operating system software, so that the application connects directly to the soundcard hardware. Each layer that is bypassed means a reduction in latency, the delay between an application sending sound to the sound being reproduced by the soundcard. In this way ASIO offers a relatively simple way of accessing multiple audio inputs and outputs independently. Its main strength lies in its method of bypassing the inherently high latency of operating system audio mixing kernels (KMixer), allowing direct, high speed communication with audio hardware. Unlike KMixer, an unmixed ASIO output is "bit identical", that is, the bits sent to the sound card are identical to those of the original WAV file, thus having higher audio fidelity.

Interface support is normally restricted to Microsoft Windows, since other operating systems (e.g. Apple's Mac OS X or Linux) do not have such mixer latency problems. In Windows Vista, KMixer has been removed and replaced by a new WaveRT port driver. WaveRT cannot provide synchronized audio to multiple devices and does not support external clocks. [ [http://createdigitalmusic.com/2007/03/22/native-instruments-releases-detailed-vista-compatibility-information/ Native Instruments Releases Detailed Vista Compatibility Information] ]

As of 2007 there is also an experimental ASIO driver for Wine, a Windows layer for Linux. This wineasio driver uses the JACK sound server as its audio back-end and allows many ASIO-aware applications to run with low-latency under WINE.

References

See also

* TASCAM's GSIF

External links

* [http://www.steinberg.de/324_1.html ASIO SDK]
* [http://www.asio4all.com/ ASIO4ALL] — a free universal ASIO driver for Windows that brings ASIO support to users of virtually all consumer-grade soundcards and integrated audio chipsets. It also supports semi-pro and pro digital audio systems.
* [http://www.asio2ks.de/ ASIO2KS] — yet another free universal ASIO driver for Windows. Project appears to have been abandoned.
* [http://www.TropicalCoder.com/ASIOTestSigGen.htm ASIOTestSigGen] — a simple, free Audio Test Signal Generator utility to test ASIO setups
* [http://www.TropicalCoder.com/MStreamPlayer.htm MultiStream ASIO Player] — a free MP3 Player for ASIO with built-in test signal generator
* [http://www.kxproject.com The kX Project] — third party WDM audio drivers for EMU10K1 and EMU10K2-based sound cards (SoundBlaster Live! and SoundBlaster Audigy 1/2/4 cards)
* [http://support.xmplay.com/file_comment.php?id=549 XMPlay plug-in] — ASIO output plug-in for XMPlay
* [http://foobar2000.org/components/index.html foobar2000 plug-in] — ASIO output plug-in for foobar2000
* [http://otachan.com/out_asio(dll).html Winamp plug-in] — open-source ASIO output plug-in for Winamp.
* [http://wiki.jacklab.net/index.php?title=Slides_wineasio&redirect=no Information regarding wineasio] - from the JackLab user's wiki
* Juce — an open-source c++ toolkit that includes support for ASIO audio devices