![background image](http://html1.mh-extra.com/html/snell-and-wilcox/prefix-cpp100/prefix-cpp100_operators-manual_1309061050.webp)
CPP100
SECTION 6
CPP1OPS
25/10/06
www.snellwilcox.com
Version 1 Issue 6
6.18
Embedded Video Flags (in the ancillary data space)
Introduction
Provision exists to embed ancillary data within the SMPTE259 serial digital output. The flag
information is embedded in the Horizontal Ancillary (HANC) data space on one line per field.
Ancillary Data Packets are divided into Type 1 and Type 2, where Type 1 uses a single
word for data identification and Type 2 uses two words for this purpose.
Prefix has been designed to embed ancillary data as type 1 utilising a single data ID for
identification of the ancillary data packet.
Packet Structure
The structure of the packet data follows the convention laid down by the reference
documents for ancillary data of type 1.
For simplicity of hardware, Prefix utilises a module, which is common to both EDH and
ancillary data generation. Both packets have identical structure although the ancillary data
packet is located immediately following the EAV group whereas the EDH packet occurs
immediately prior to the SAV group.
Only the top 8 MSB’s of the output data stream are used to ensure no losses through 8-bit
equipment.
The structure is shown below.