MPEG AUDIO ADAPTER SUPPORTS AES-18 MESSAGING 

NEWCASTLE, DE (July 1, 1999) - AudioScience Inc., a manufacturer of digital audio products for the broadcast industry, has announced the ASI4601 PCI digital audio adapter. The ASI4601 is distinguished from other adapters in it's class by the ability to insert and extract AES-18 messages over its AES3-3id-1995 digital audio I/O.

The AES18 messaging protocol has been implemented on the ASI4601 according to the AES18-1996 specification. It is able to receive messages from the digital input and insert messages onto the digital output. If AES18 is not present on the input then the ASI4601 can act as an AES18 originator with configurable channel, address, block rate, repeatability and priority.

The adapter contains two digital audio inputs and one output. One of the inputs is used as a recording source and contains a Sample-Rate-Converter (SRC) which allows recordings at sample rates other than digital audio source. The digital audio output also contains a SRC, and can be sample-rate synchronised to the other digital input. This allows the digital audio to be locked to a "house sync" independant of the playback rate. The digital audio inputs and outputs conform to the AES-3id-1995 standard which specifies sending AES3 data over a coaxial cable using BNC type connectors. This allows transmission to reach upto 1000 meters, compared with 100 meters for the AES3 twisted pair implementation.

Four streams of MPEG playback and one stream of MPEG record simultaneously are provided. Four physical analog outputs and one analog input are available. One of the outputs contains a digital mix of the four playback streams. All analog outputs and inputs are electronically balanced and have software selectable levels of between -10 and +20dBu. 20bit Crystal Semiconductor oversampling A/D and D/A converters are used to provide greater than 92dB of Signal-to-Noise Ratio (SNR) and less than 0.005% of Total Harmonic Distortion+Noise (THD+N) when recording or playing.

Advanced features of the ASI4601 include 8Mbytes of on-board RAM for audio data buffering, providing glitch free audio. Automatic volume fades implemented in DSP firmware, free up CPU time, by removing the burden of having the automation software both track and fade the volume controls. By just specifying a start gain, end gain and duration, the adapter will fade one or all of the volume controls on the adapters mixer in real-time.

Driver software for Windows95,98 and Windows NT is available from AudioScience's web site (www.audioscience.com). All the standard waveIn, waveOut and mixer APIs are supported. AES-18 functionality is surfaced through custom mixer controls.

The ASI4601 PCI based digital audio adapter is designed and manufactured in the USA by AudioScience Incorporated, 42C Reads Way, NewCastle, DE 19720, telephone +1-302-324-5333, FAX +1-302-738-9434. The companies web site is located on the Internet at www.audioscience.com
 

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