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Visitor aforizma1842
Visitor
1,066 Views
Registered: ‎05-08-2018

BT.656 conversion

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Hello everyone,

I want to convert 8-bit ITU-R BT.656 4:2:2 digital data to 16-bit YCbCr 4:2:2 data stream. How can ı do this?

Can ı use Video in to Axi4-Stream ip Block? 

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1 Solution

Accepted Solutions
Adventurer
Adventurer
1,178 Views
Registered: ‎07-18-2011

Re: BT.656 conversion

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The Video In to AXI4-Stream IP cannot directly handle the interleaved 27MHz 8-bit BT.656 datastream, nor can it convert it to  the 13.5MHz 16-bit Y/C 4:2:2 format.

 

The IP can only handle the 16-bit Y/C 4:2:2 input format.   If you look at UG1037 Table 4-9, which lists all the AXI4-Video Stream video formats, you will see that YUV 4:2:2 is VF code 0. and is formatted as Y on the 8 lsb's, and Cr/Cb on the 8 msb's of the 16-bit word.

 

In addition, the Video In to AXI4-Stream IP requires Vsync, Hsync, and Data Valid, or Vblank, Hblank, and Data Valid, or both.  It cannot extract the embedded syncs from the BT.656 data format.

 

In order to process a BT.656 27MHz 8-bit interleaved datastream with the Video In to AXI4-Stream converter IP, you must write a custom IP block to first decode the interleaved 8-bit BT.656 data to separate the Y and C, and retrieve the embedded sync codes (EAV/SAV) to generate timing signals for the IP.  

 

This is fairly simple,  all you need to do is look for the FF,00,00,XY data sequence at the EAV/SAV times to extract the H,V, and F bits from the XY byte, and use a few latches to extract the Y and CbCr onto separate 8-bit outputs and concatenate them together to form the 16-bit 13.5MHz dataword as shown in VF code 0.   You can clock everything at the 27MHz BT.656 input clock rate and generate a clock enable signal to gate it at the required 13.5MHz data rate for the Video In to AXI4-Stream IP block.  You can also generate the required Hblank, Vblank, and Data Valid signals from the FVH word.

 

5 Replies
Scholar drjohnsmith
Scholar
1,043 Views
Registered: ‎07-09-2009

Re: BT.656 conversion

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yes you can..

 

Please mark the question as answered  !!  :->   

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Adventurer
Adventurer
1,179 Views
Registered: ‎07-18-2011

Re: BT.656 conversion

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The Video In to AXI4-Stream IP cannot directly handle the interleaved 27MHz 8-bit BT.656 datastream, nor can it convert it to  the 13.5MHz 16-bit Y/C 4:2:2 format.

 

The IP can only handle the 16-bit Y/C 4:2:2 input format.   If you look at UG1037 Table 4-9, which lists all the AXI4-Video Stream video formats, you will see that YUV 4:2:2 is VF code 0. and is formatted as Y on the 8 lsb's, and Cr/Cb on the 8 msb's of the 16-bit word.

 

In addition, the Video In to AXI4-Stream IP requires Vsync, Hsync, and Data Valid, or Vblank, Hblank, and Data Valid, or both.  It cannot extract the embedded syncs from the BT.656 data format.

 

In order to process a BT.656 27MHz 8-bit interleaved datastream with the Video In to AXI4-Stream converter IP, you must write a custom IP block to first decode the interleaved 8-bit BT.656 data to separate the Y and C, and retrieve the embedded sync codes (EAV/SAV) to generate timing signals for the IP.  

 

This is fairly simple,  all you need to do is look for the FF,00,00,XY data sequence at the EAV/SAV times to extract the H,V, and F bits from the XY byte, and use a few latches to extract the Y and CbCr onto separate 8-bit outputs and concatenate them together to form the 16-bit 13.5MHz dataword as shown in VF code 0.   You can clock everything at the 27MHz BT.656 input clock rate and generate a clock enable signal to gate it at the required 13.5MHz data rate for the Video In to AXI4-Stream IP block.  You can also generate the required Hblank, Vblank, and Data Valid signals from the FVH word.

 

Scholar watari
Scholar
987 Views
Registered: ‎06-16-2013

Re: BT.656 conversion

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Hi @aforizma1842

 

Would you refer data sheet of device which  supports ITU BT.656 ?

Also, would you refer ITU BT.656's specification ?

 

You can do what you want to do.

 

Best regards,

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Scholar drjohnsmith
Scholar
965 Views
Registered: ‎07-09-2009

Re: BT.656 conversion

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To fill out a little

 

Your looking at converting video format from one thing to another,

 

You ask , can it be done, this is an FPGA forum, 

 

      FPGAs are used to do this sort of thing all the time.

 

 

The question I think your wanting to ask is, how !

 

Now that is a much bigger question, 

    a much much bigger question, as you can not just plug together and away you go.

        you need to code,,

 

We need to know where are you at on the FPGA codding knowledge level.

 

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Moderator
Moderator
905 Views
Registered: ‎11-09-2015

Re: BT.656 conversion

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Hi @aforizma1842,

 

There was a good discussion on this topic. Did you find what you needed? If yes could you kindly mark a reply from @reaiken, @watari or @drjohnsmith (the one which helped you the most) as accepted solution (click on the accept as solution below the reply when logged in)?

 

Thanks,


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