Altera Serial Digital Interface (SDI) MegaCore Function - Manual (Page 34)

3–4 Chapter 3: Functional Description
Block Description
Serial Digital Interface (SDI) MegaCore Function February 2013 Altera Corporation
User Guide
Table 3–1 lists the bit allocation for txdata.
For HD-SDI operation, the current video line number is inserted at the appropriate
point in each line. A CRC is also calculated and inserted for the luma and chroma
channels.
The parallel video data is scrambled and NRZI encoded according to the SDI
specification.
The transceiver converts the encoded parallel data into the high-speed serial output
(parallel-to-serial conversion).
HD-SDI LN Insertion
SMPTE292M section 5.4 defines the format of two words that are included in each
HD-SDI video line to indicate the current line number. The HD-SDI LN insertion
module takes the lower 11-bit tx_ln, and formats and inserts it as two words in the
output data. The HD-SDI LN insertion module accepts the current line number as an
input.
1
For more information about the line insertion for other video standards, refer to the
description for
tx_ln signal in Table 3–16 on page 3–41 .
The LN words (LN0 and LN1) overwrite the two words that follow the “XYZ” word
of the EAV TRS sequence. The same value is included in the luma and chroma
channels.
For correct LN insertion, you must assert the tx_trs signal must be asserted for the
first word of both EAV and SAV TRSs (refer to
Figure 3–31 on page 3–47 and
Figure 3–32 on page 3–48 ).
1
If the system does not know the line number, you can implement logic to detect the
output video format and then determine the current line. This function is outside the
scope of this SDI MegaCore function.
HD-SDI CRC Generation and Insertion
SMPTE292M section 5.5 defines a CRC that is included in the chroma and luma
channels for each HD-SDI video line. The HD-SDI CRC module generates, formats,
and inserts the required CRC in the output data.
The HD-SDI CRC module identifies the words that you must include in the CRC
calculation, and also determines where you must insert the words in the output data.
The formatted CRC data words (YCR0 and YCR1 for the luma channel, CCR0 and CCR1
for the chroma channel) overwrite the two words that follow the line number words
after the EAV. A separate calculation is provided for the luma and chroma channels.
Table 3–1. Bit Allocation for txdata for Supported Video Standards
txdata SD-SDI HD-SDI 3G-SDI Level A 3G-SDI Level B
[19:10] Unused Y Y
Cb, Y, Cr, Y
multiplex (link A)
[9:0]
Cb, Y, Cr, Y
multiplex
C C
Cb, Y, Cr, Y
multiplex (link B)