VISTEK V1633/A & V1633/D
sdi audio multiplexer
10
Issue 4
3.8
Internal Settings
Switch
Title
Description
Left
Right (= ON)
0
ANC Blank
Blank all ancillary data from the output
Blank
Pass
1
Reserved
2
Reserved
3
A->A, A->B / A->A, B->B
A-> both
A->A,B->B
4*
REF SDI
Select video reference between Ext. Ref. and SDI
EXT
SDI
5
LSB
1
0
6
Op. Mode
Select 1 of 8 operating modes
1
0
7
MSB
(switch ON = 0, OFF = 1)
1
0
For normal operation all switches should be set to the right (ON).
* The sense of this switch was incorrectly stated in earlier versions of this manual.
3.9
Operating Modes
Three operating modes have been incorporated into the V1633A. Mode 0 is a full SMPTE specification,
allowing synchronous or asynchronous multiplexing, i.e. the AES inputs need not be locked to the SDI or
each other when operating in DireCT mode (in Video or AES reference mode the audio is automatically
synchronised).
However because some de-multiplexers on the market make certain assumptions about the multiplexed
data. For these systems two other modes have been incorporated.
In any one line of video there may be 3 or 4 samples of audio data from each AES stream. Mode 1 forces the
number of samples from each channel to be the same i.e. 3 from A and 3 from B, or 4 from A and 4 from B;
a combination is not allowed in this mode.
Mode 2 is a basic operating mode, which is entirely synchronous, and does not insert control packets,
suitable for basic de-multiplexers types.
Mode
Description
0
Full SMPTE spec. Audio embedding, D1 / D2.
1
AES channels A & B packets aligned
2
Basic Embedding, no Control Status. No asynchronous capability
3
= mode 0
4
= mode 1
5
= mode 2
6
= mode 0
7
= mode 1
3.10
Ancillary Blanking
If the SDI into the V1633A has audio already embedded on the selected group, it is necessary to remove any
data already in the ancillary data space, or select another group (see Section 3.6) This can be done by
setting S0 of the internal DIL switch accordingly. This can also be set over the remote control.
If the Ancillary data is set to be blanked then ALL data in the ancillary space will be removed, not just the
audio data.
