Altera SDI II MegaCore - Manual (Page 11)

SMPTE RP168 Switching Support
The SMPTE RP168 standard defines the requirements for synchronous switching between two video
sources to take place with minimal interference to the receiver. The RP168 standard has restrictions for
which lines the source switching can occur.
The SDI II IP core has flexibility and does not restrict you to switch at only a particular line defined in the
RP168 standard. You can perform switching at any time between different video sources as long as the
source has similar standard and format. After switching, all the status output signals, including the
rx_trs_locked
,
rx_frame_locked
, and
rx_align_locked
signals, remain unchanged. You should
should not see any interrupts at downstream.
SD 20-Bit Interface for Dual/Triple Standard
For a common SD interface, the serial data format is 10 bits wide, whereas for HD or 3G, the data format
is 20 bits wide, divided into two parallel 10-bit datastreams (known as Y and C).
To make the interface bit width common for all standards in the dual standard or triple standard SDI
mode:
• The receiver can extract the data and align them in 20-bit width
• The transmitter can accept SD data in 20-bit width and retransmit them successfully
The timing diagrams below show a comparison of data arrangement between 10-bit and 20-bit interface.
Figure 2-5: SD 10-Bit Interface
rx_clkout(148.5 MHz)
rx_dataout[19:10]
rx_dataout[9:0]
rx_dataout_valid
Don’t Care
Cb
Y Cr Y Cb
• The upper 10 bits of
rx_dataout
are insignificant data.
• The lower 10 bits of
rx_dataout
are Luma (Y) and chroma (Cb, Cr) channels (interleaved).
• The 1H 4L 1H 5L cadence of
rx_dataout_valid
repeats indefinitely (ideal).
Figure 2-6: SD 20-Bit Interface
rx_clkout(148.5 MHz)
rx_dataout[19:10]
rx_dataout[9:0]
rx_dataout_valid
Cb
Y
Cr
Y Y
Cb
• The upper 10 bits of
rx_dataout
are Luma (Y) channel and the lower 10 bits are Chroma (Cb, Cr)
channel.
• The 1H 10L cadence of
rx_dataout_valid
repeats indefinitely (ideal).
2-6 SMPTE RP168 Switching Support
UG-01125
2015.05.04
Altera Corporation SDI II IP Core Overview
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