Onkyo AC-3 INSTRUCTIONS

AC 3 Introduction:

* AC-3 was developed by the Digital Coder group at Dolby Laboratories as high-quality, low-complexity multi-channel audio coding format. It does process lower data rates for a given level of audio quality than an ensemble of single channels single transmission of several channels coding. Dolby AC3 was developed as a multi-channel audio coder operating at a bit-rate only little more than required for two channel coding.

* The AC-3 algorithm is independent of the number of coded channels. Parameters as bit-rate and number of channels can be tailored to particular applications. Current implementations have standardized on the SMPTErecommended 5.1 channel arrangement. AC -3 conveys the 5.1 channel arrangement with data rate of 320 Kbps. * AC-3 is a block-structured coder with typically 512 samples per block. One or more blocks of data are collected at the input buffer of each channel before proceeding with the additio nal pro ce ssing.

* The decoder, like the encoder, is block structured and m ai ntains sync with the incoming data-stream. * AC-3 has been in active use for years in t he production of Dolby Digital film soundtracks. * AC-3 can process 20-bit dynamic range digital audio signals over a frequency range from 20Hz to 20kHz (-3dB at 3Hz and 20.3 kHz).

* The lo-frequency effects chann el covers 20 to 120 Hz (-3 dB at 3Hz and 121Hz). * Sampling rates are s upported: 32kHz, 44.1kHz, and 48kHz. * Data rates range from 32 kb/s for a single mono channel to up 640 kb/s for special applications. * Dolby AC-l

was first used in 1985 and has been adopted for DBS services and satellite communication networks. * Dolby AC-2 is a part of the Dolby FAX ® system, used to link remotely located studios and post production facilities.