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BT.656 video protocol

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shaiko

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Hello,

I understand that the BT.656 is a serial video protocol.
It sends 8 bit packets to the Rx end where the reciever assembles a frame from those 8 bit frames.

My question is simple - HOW ?
 

shaiko

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This info is to high level...

Let me ask simpler questions:
Is it true that the protocol is serial?
From how many bits does each frame consist?
 

prady019

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Hello m facing some/many problems in understanding bt 656 protocol, i read this document's but still info is lacking in there.
Help me out

thanks
 

lucbra

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BT.656 is digital component video in 4:2:2 format.
The interface is either serial or parallel and contains 8 or 10 bit.
when 10 bit data is transmitted, all bits are used. when 8 bits, bit 9 to 2 are used where bit 9 is MSB.
Data is transmitted in Cb, Y, Cr, Y, Cb, Y, Cr, Y, ... a block of video starts with SAV and ends with EAV.

Timing reference consists of a 4 word sequence : 3FF 000 000 XYZ, with XYZ is (1, F, V, H, Protection bit3, Protection bit2, Protection bit1, Protection bit0, 0, 0)

All this info can be found in this document
 

prady019

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ur effort is appreciable.

i have this document, i read many document for this BT 656 n SMPTE 292. An this basic info is already extracted.
i m receiving SMPTE 292 signal and after receiving this i have to decode to BT 656.
so i want to get knowledge of SMPTE 292 decoder and then convert this video signal to 8 bit BT 656.
 

lucbra

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Do you know that this function exists as a standard IC? Just perform a search on SD-SDI (standard definition serial digital interface)

Otherwise, if you need to build the functionality in an FPGA, you need to be aware that some of the input functions are pure analog. The other functions can be implemented in an FPGA. Information can be found on the Xilinx website.
You'll need CDR, flywheel, sync pattern decoders, barrel shifters, ...
 

prady019

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yes before that i would like to get some more knowledge on BT 656 and SMPTE 292.
 

lucbra

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One good source to start from is Video Demystified which is concidered the 'bible' for digital video.
other sources are datasheets from gennum (actually Semtech as it is acquired in jan-2012)
 

prady019

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Yes i tried, but that was a bouncer to me.
 

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