The Advanced Linux Sound Architecture (ALSA) is a major component in most Linux distributions. At PlanetCCRMA is an essential part since most audio and MIDI applications used at CCRMA depend on it. Extensive research and testing is done on a daily basis to be up-to date with the latest drivers and kernel related ALSA API. Recently many improvements have been done to many old and newer hardware sound-cards but perhaps attention should be paid toward USB related audio and MIDI devices because newer hardware seems to be geared to this direction in these days.

Testing was performed with various commercial USB-MIDI and USB-AUDIO interfaces to the extend that we are able to consider USB as good as an alternative (or better in some cases) to serial and parallel interfaces and even to audio sound-cards. The “usb-audio” module of ALSA has been updated and improved to the extend that most hardware tested, behaved in a reliable fashion with standard Linux and PlanetCCRMA applications. In our tests hardware included not only interfaces but controllers such as keyboards and wheels.

MIDI is a very important part at CCRMA because of its close relationship with human computer interface (HCI). Our testing focused not only on ALSA sequencers but also with the PD Linux environment and more specialized software such as Max Matthews' Scanned synthesis program and Craig Sapp's Improv. In most cases USB-Audio performed accurately even with the combination of Scanned synthesis audio and Radio Baton MIDI input using M-Audio's Quattro interface. With the Quattro we were also able to listen to four discrete 44.1KHz audio channels and record audio at 96KHz sampling rate.

For more updated information on the ALSA “usb-audio” module and for additional USB audio an related issues, point to the USB audio web pages on the Nano HOWTOs section at PlanetCCRMA @ Home

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