dCS 974 User Manual

Manual for Software Version 1.0x

dCS Ltd

May 2001

 

 

SDIF-2 Message Handling

The SDIF-2 interface is a 4 wire NRZ interface - so the DC level on each signal line may not be constant. It contains 20 bits of audio data and has a block structure of 256 stereo samples, rather than the 192 of AES/EBU. There are 8 bits of message per channel per sample - with a further 3 bits being used for an "illegal code" based sync code. Of the 8 bits per sample, the 8 in the first sample are reserved for system messaging, and the rest are for User messages.

The 4 wires are:

Ground return Left Channel Right Channel Wordclock

The sync codes enable data recovery without the word clock, if necessary, but with the number of data formats in current operation, this method of locking is strongly discouraged.

The SDIF-2 message is given in the table following. The dCS 974 implementation sets all bits of the User message to "0".

DESCRIPTIONDefinitionDefault

Undefined

 

Message

0000 0xxx

0000 0xxx

Emphasis

xxxx x00x

xxxx x00x

No emphasis

Emphasis (15sec, 50sec)

xxxx x01x

 

Dubbing Prohibit

 

 

Dubbing allowed

xxxx xxx0

xxxx xxx0

Dubbing inhibited

xxxx xxx1

 

Block Code

 

 

Start of block

xxxx xxxx 1...

as required

Not start of block

xxxx xxxx 0...

as required

Table 15 - SDIF-2 Message Table

SDIF-3 Message Handling

At present, no messaging is implemented in SDIF-3.

Manual part no: DOC1241121A1

Page 90

Document No: OS-MA-A0124-112.1A1

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