VISTEK V1667, V1667/SY & V1667/SY-VHS
12-bit pal/ntsc to sdi adaptive
comb filter decoder
HU-V1667&SY&SY-VHS
19
Because of the precise separation of luminance and chrominance in the V1667 it is possible to re-assemble
the NTSC signal without any significant loss of quality, even after repeated decoding and re-encoding
processes.
8.4.3
Does the added data degrade my picture?
The data is transmitted outside the analogue NTSC picture area and at a very low level. This ensures it is
invisible to the viewer of the digital image.
8.4.4
Will digital equipment in the path pass the VisLock signal?
As the Vislock data is integrated within the active picture area of the serial digital video signal, it is
transmitted accurately through most professional digital video plant including switchers, routers,
synchronisers, audio embedders and de-embedders, caption and logo inserters etc.
Certain equipment such as standards converters and effects generators may destroy the relationship
between subcarrier and line frequency such that after processing it is impossible to accurately re-assemble
the NTSC signal. However, these units often significantly reduce many of the re-encoding impairments.
8.4.5
How is VisLock Implemented?
The Vistek V1667 decoder and V1668 encoder modules are now available with VisLock, no additional
equipment is required. The V1667 decoder converts the NTSC to serial digital (SDI) format and inserts the
VisLock data. When the serial digital signal is subsequently converted back to NTSC in a VisLock compatible
V1668 encoder the added data is read and the signal timed to ensure that optimum encoding quality is
achieved and the signal timed to the genlock reference signal.
