Altera Serial Digital Interface (SDI) MegaCore Function - Manual (Page 38)

3–8 Chapter 3: Functional Description
Block Description
Serial Digital Interface (SDI) MegaCore Function February 2013 Altera Corporation
User Guide
Table 3–2 lists the bit allocation for rxdata.
The receiver interface extracts and tracks the F, V, and H timing signals in the received
data. Active picture and ancillary data words are also identified for your use.
For HD-SDI, the received CRC is checked for the luma and chroma channels. The LN
is also extracted and provided as an output from the design.
NRZI Decoding and Descrambling
The descrambler module provides the channel decoding function that is common to
both SDI and HD-SDI. It implements the NRZI decoding followed by the required
descrambling. The algorithm indicated by SMPTE259M figure C.1 is iteratively
applied to the receiver data, with the LSB processed first.
Word Alignment
The aligner word aligns the descrambled receiver data such that the bit order of the
output data is the same as that of the original video data.
The EAV and SAV sequences determine the correct word alignment. Table 3–3 lists the
pattern for each standard.
The aligner matches the selected pattern in the descrambled receiver data. If the
pattern is detected at any of the possible word alignments, then a flag is raised and the
matched alignment is indicated. This process is applied continuously to the receiver
data.
The second stage of the aligner determines the correct word alignment for the data. It
looks for three consecutive TRSs with the same alignment, and then stores that
alignment. If two consecutive TRSs are subsequently detected with a different
alignment, then this new alignment is stored.
The final stage of the aligner applies a barrel shift function to the received data to
generate the correctly aligned parallel word output. For this SDI MegaCore function,
the barrel shifter allows the design to instantly switch from one alignment to another.
Table 3–2. Bit Allocation for rxdata for Supported Video Standards
rxdata 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)
Table 3–3. EAV and SAV Sequences
Video Standard EAV and SAV Sequences
SDI 3FF 000 000
HD-SDI 3FF 3FF 000 000 000 000
3G-SDI Level A 3FF 3FF 000 000 000 000
3G-SDI Level B 3FF 3FF 3FF 3FF 000 000 000 000 000 000 000 000