Altera SDI II MegaCore - Manual (Page 57)

Figure 4-18: Line Number Insertion and Signal Requirements
Figure below illustrates the line number insertion and signal requirements. For a correct line insertion,
assert the
tx_trs
signal for the first word of both EAV and start of active video (SAV) TRS.
3 FF 000 000 XYZ LN0 CRC0 CRC1 LN1
XXX VALID XXX
INPUT DATA
TX_LN
TX_TRS
Insert/Check CRC
The HD-SDI can optionally include a line-based CRC code, which makes up two of the EAV extension
words as defined in the SMPTE292M specification.
This submodule calculates the CRC based on the LFSR approach in the SMPTE specification. Note that
you can configure this submodule to either insert or check the CRC.
For the transmitter, the core formats and inserts the CRC into two CRC EAV extension words—CRC0
and CRC1. The Match TRS submodule indicates to this submodule when to calculate, reset, and insert the
CRC into the stream. For correct CRC generation and insertion, assert the
tx_trs
signal for the first word
of both EAV and SAV TRS as shown in the Insert Line timing diagram. Perform CRC insertion only
when the top level port,
tx_enable_crc
, is set to logic 1.
For the receiver, the core checks the CRC against the value of CRC0 and CRC1 that appear in the
incoming stream. If there is a mismatch between the locally calculated value and the value in the stream,
this submodule indicates an error. The Match TRS submodule indicates when the CRC0 and CRC1 words
are present in the incoming data stream.
Insert Payload ID
The SMPTE352M specification defines an ancillary packet type that provides specific information about
the video payload carried by a digital interface. These payload ID packets carry information such as the
interface type, sampling structure, component bit depth, and picture update rate. Recent SMPTE
interfaces such as dual link HD-SDI and 3G-SDI require the payload ID packets because it is very difficult
to properly interpret the video data without the packet information from the payload ID packets.
The payload ID packet must be on specific video lines locations at the beginning of the horizontal
ancillary (HANC) space, which is right after the EAV, or CRC words that follow the EAV on the
interfaces using CRC words.
Table 4-1: Payload ID Packet Location
Video Format Field Line Number
525i
1 13
2 276
UG-01125
2015.05.04
Insert/Check CRC 4-15
SDI II IP Core Functional Description Altera Corporation
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