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AR# 59903

LogiCORE SMPTE SD/HD/3G-SDI - How do I capture the Field ID from an in SDI RX when the input is interlaced?


How do I capture the Field ID from an in SDI RX when the input is interlaced?


The SMPTE SDI core does not separate out this bit independently.

The fourth word of each four-word EAV and SAV sequence is called the XYZ word.

It has the following format:

In the XYZ word, bit 8 is the field ID bit.

The SDI core only asserts the following signals when the XYZ word is being output on the various video ports such as rx_ds1a:

  1. rx_eav
  2. rx_sav

You can confirm that the XYZ word is present on the video output ports when these signals are asserted.

Here is a Verilog example that would capture the current field:

always @ posedge (rx_usrclk)
            if (rx_eav)
                        field_id <= rx_ds1a[8];
This captures the field ID bit at the beginning of each line when the EAV occurs. It is recommended to use rx_eav here.

The rx_sav signal can be used instead, but it will not capture it at the beginning of the line.  

Alternatively you could capture the F bit from other video component ports, however the rx_ds1a port is the only one of the four video component output ports that is guaranteed to be active in every SDI mode.


AR# 59903
Date 09/16/2014
Status Active
Type General Article
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