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Visitor dmtutd
Visitor
622 Views
Registered: ‎02-08-2018

Vertical back porch from SD/HD/3G SDI Core?

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For my implementation, I need to determine the "start" of the incoming HD-SDI video (VSYNC, not active video), in order to do some preprocessing before the active video comes in. From the Product Guide, the only port from the core that seems useable is the rx_line_a port, which is described as:

 

"The current line number captured from the LN words of the Y data

stream is output on this port. This output is valid in HD-SDI and

3G-SDI modes, but not in SD-SDI mode. In 3G-SDI level B mode, the

output value is the line number from the Y data stream of link A or

HD-SDI signal 1. For any case where the interface line number is not

the same as the picture line number, such as for 1080p 60 Hz carried

on 3G-SDI level B or dual link HD-SDI, the output value is the

interface line number, not the picture line number."

 

What I am trying to determine, from the last line, is what is the "picture line number"... does this include the line numbers for the blanking lines, or are these only line numbers for active video lines? Per SMPTE ST 292, it states:

 

5.1  "Digital active line and digital line blanking shall consist of 10-bit words as defined by the source format document..." (SMPTE 296, 274, etc.)

 

5.2 "Timing references SAV, EAV, line number and CRCs for each of the two parallel data streams shall be formatted as shown in Figure 2"

 

3FF, 000, 000, XYZ (represents EAV)

LN0, LN1 (represents LN as described in rx_line_a port description)

YCR0, YRC1 (represents CRC)

....

3FF, 000, 000, XYZ (represents SAV)

 

From those descriptions, it seems that LN would include line numbers from what SMPTE refers to as "digital line blanking" but I just wanted to confirm that if I get line number 1 on that port, that it would represent the start of the vertical back porch?

  

Thanks so much in advance.

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smpte296.PNG
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1 Solution

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Xilinx Employee
Xilinx Employee
561 Views
Registered: ‎08-02-2007

Re: Vertical back porch from SD/HD/3G SDI Core?

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@dmtutd

 

From your description, you are working on  HD-SDI mode, not 3G-SDI level B or dual link HD-SDI, right?

 

If this is the case, you shouldn't refer to the sentence below :

"For any case where the interface line number is not the same as the picture line number, such as for 1080p 60 Hz carried

on 3G-SDI level B or dual link HD-SDI, the output value is the interface line number, not the picture line number."

 

For HD-SDI, the interface line number should be the same as the picture line number. Please take a look at ST274M, it means that

A line of digital video extends from the first word of EAV through the last word of video data.

 

As you can see in the screenshot, the blanking codewords are contained between the first word of EAV and the last word of Video data.line.JPG

.

3 Replies
Xilinx Employee
Xilinx Employee
562 Views
Registered: ‎08-02-2007

Re: Vertical back porch from SD/HD/3G SDI Core?

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@dmtutd

 

From your description, you are working on  HD-SDI mode, not 3G-SDI level B or dual link HD-SDI, right?

 

If this is the case, you shouldn't refer to the sentence below :

"For any case where the interface line number is not the same as the picture line number, such as for 1080p 60 Hz carried

on 3G-SDI level B or dual link HD-SDI, the output value is the interface line number, not the picture line number."

 

For HD-SDI, the interface line number should be the same as the picture line number. Please take a look at ST274M, it means that

A line of digital video extends from the first word of EAV through the last word of video data.

 

As you can see in the screenshot, the blanking codewords are contained between the first word of EAV and the last word of Video data.line.JPG

.

Visitor dmtutd
Visitor
553 Views
Registered: ‎02-08-2018

Re: Vertical back porch from SD/HD/3G SDI Core?

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Thank you for your reply.

 

My question was mostly to understand the difference between interface line number and picture line number. I wasn't sure if picture line number referred to active line number, versus all line numbers (including blanking lines). I'm not as familiar with 3G-SDI level B or dual-link HD-SDI, but now I assume those formats split the video lines across two different links.

 

However, I think I understand now that the interface line number has more to do with the formats that have multiple links, whereas the single link of HD-SDI interface would send all 750 lines across the same link, meaning interface lines = picture lines. I also see that spelled out now in SMPTE296 where it discusses what SAV/EAV codes are for lines 1-25 and 746-750 (vertical blanking lines), so I can see how lines 1-750 will be output on LN.

 

Thanks for your time.

smpte296_line_numbers.PNG
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Moderator
Moderator
543 Views
Registered: ‎11-09-2015

Re: Vertical back porch from SD/HD/3G SDI Core?

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Hi @dmtutd,

 

If the reply from @xud is enough for you on this, please kindly close the topic by marking her reply as accepted solution (click on accept as solution button below the reply while logged in).

 

Thanks and Regards,


Florent
Product Application Engineer - Xilinx Technical Support EMEA
**~ Don't forget to reply, give kudos, and accept as solution.~**
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