Ross TES9, Руководство пользователя программного обеспечения

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4–6 • Transparent Module TES9 Software User Manual (Iss. 04)
Two applications for this mode are:
• Inserting Caption Distribution Packets (CDPs), carrying DTV Closed Captioning data, as
defined by CEA-708.
• Inserting Subtitle Distribution Packets (SDPs), carrying WST teletext data and EST
Enhanced Systems Teletext, as defined by SMPTE 334M.
When Packet mode is being used for one of these applications, the values for the various fields
must conform to the applicable standard. For any custom applications, however, the transmit
computer need only ensure that the fields conform to the format given above.
Packet mode of operation applies only to encoding. Decoding is done using Byte mode,
regardless of the mode used to encode the data. When decoding, all of the bytes, from the
Identifier to the last byte of Footer data, inclusive, are sent to the receiving computer.
Packet Mode Priority
These options enable you to control the arbitration between incoming VANC (network) data and
locally-sourced (local) data, for each transparent module in the TES9. There are three mutually
-exclusive options: overwrite upstream, local priority, and upstream priority.
Overwrite Upstream
When there are two copies of the data, the TES9 deletes the DID and SDID packets from the
upstream video. For example, any network data having the same DID and SDID values as the
local data is unconditionally deleted. This enables local data to be inserted without interference
from unwanted network data. This is the default setting.
Local Priority
This option enables local data to be inserted whenever it is available, overwriting any network
data. Network data passes through whenever local data has stopped arriving at the assigned port
for longer than a defined time out period.
This mode enables the local user to insert transparent data simply by sending it to the TES9, and
to revert to passing network data by simply stopping the sending of local data to the TES9.
Upstream Priority
This option enables network data to pass through whenever it is available, and any local data is
discarded. Local data is inserted whenever network is absent for longer than the defined time out
period.
Table 4.1 Packet Components
Parameter Description
{Identifier}
a 2-byte sequence indicating the start of the packet
{Length}
a 1-byte unsigned number indicating the number of bytes in the
entire packet, from the first byte of the Identifier to the last byte
of the Footer data, inclusive
{data}
a sequence of any 8-bit data, maximum number of data bytes is
248 (255-7)
{Footer ID}
one byte with a hexadecimal value of 0x74, indicating the start of
the Footer data
{Footer data}
a 3-byte sequence of any 8-bit data