dCS 900E / 902E User Manual Manual for Software Versions 1.3x to 1.5x
dCS Ltd 12
th
June 2000
Manual part no: DOC0029021E1 Page 42 Document No: OS-MA-D0002-902.1E1
Contact dCS on + 44 1799 531 999 email to: more@dcsltd.co.uk
(inside the UK replace + 44 with 0) web site: www.dcsltd.co.uk
AES3 (AES/EBU) Format
Message Handling -
The AES/EBU interface transmits a data structure that conforms to the dCS
version of AES3-1992. This contains 28 bits of Manchester encoded data, and a
4 bit near-Manchester encoded preamble in a subframe, and subframes are
further assembled in a block and frame structure. Each subframe contains:
• preambles, to allow the receiver to sync up
• up to 24 bits of audio data, transmitted lsb first
• V, a validity bit
• U, a user bit, for the "User Message"
• C, a Channel Status bit, for the "System Message"
• P, a parity bit
IMPORTANT! The AES/EBU interface and the SPDIF interface have similar data
structures, although the messages are completely different. The two
structures are identified in the data domain by the use of the
Consumer/Professional bit (bit 1 in the message). A "1" indicates AES/EBU
format, a "0" indicates SPDIF format.
The default AES/EBU message attached to the output data by the unit before
being changed by the user is as follows:
Professional: On
Non-Audio: Off
Mode: Stereophonic
Source: DCS1
Destination: null
For more information on the way dCS implement the AES3 system message to
handle higher sample rates, see the Appendix to this manual. For the formal
definition of the AES3 interface, see footnote
8
, from the AES.
8
AES3-1992 (ANSI S4.40-1992) “AES Recommended practice for digital audio engineering – Serial
transmission format for two-channel linearly represented digital audio data”.
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