ADV7180 inputs

Can the ADV7180 support ITU-R BT.601. I know the ADV7180 encoder the input analog signal into a ITU-R BT.656 output. Not sure if when the device supports ITU-R BT.656 it will inherently support ITU-R BT.601 since it’s just a black and white picture.

We will be passing NTSC, PAL, and CCIR  Black/White 1.4V video. Will the ADV7180 support 1.4V CCIR BW video?  If the 1V peak to peak sampling of the ADV7180 is an issue, would a simple voltage divider to bring that 1.4V to a voltage less than 1V pp work?

If we’re dealing with BW analog video would the CrCb element of the signal be all 0s? If so than if we use the 16-bit mode of the ADV7180, bits 0-7 would be all 0s in the 16-bit mode, correct? (data sheet table 100). The reason for this questions is because we noticed that if we use the 16-bit mode on the output from the ADV7180 the digital datarate will be large compared to what we have allocated. We allocated 156Mbps per channel for the digitized video. If we use the 16-bit mode we get 16*27MHz LLC clock = 432Mbps! However, since the customer has stated that they’ll be passing BW video through this device, I believe CrCb = 0, so even if we use bits 8-16, with 0-7 all 0s, this should give knock down the datarate to 8*27 = 216Mbps, which we can work with. We’ll have to increase our initial allocation, however not drastically. Just want to make sure in the case of BW video, inferring that CrCb = 0, the 8 LSB can be ignored without any issues. We need to confirm this to be absolutely certain this is safe and will work.

  • 0
    •  Analog Employees 
    •  Super User 
    on Oct 1, 2013 8:47 PM

    BT.601 uses the same data encoding in the active pixel region, the only major difference is 601 use sepearate syncs instead of embedded syncs.

    Yes, you can use the voltage divider to bring the input levels down to acceptable levels.

    If you are only dealing with NTSC, 16 bit wide bus, 422 format then the output will be two channels running at 13.5MHz pixel rate, one luminace and one chromance channel.  The luminance is the BW channel.  If the input is truly BW then the chromance will be a mid point value, chromance has a range of -1 to 1

    the 27MHz pixel clock occurs when you are running YCbCr 422 across an 8 bit bus.  YCrCb 422 across a 16 bit bus has a 13.5MHz pixel rate.

  • 0
    •  Analog Employees 
    on Oct 1, 2013 9:42 PM

    Hi Hank,

    The datasheet mentions 601 several times. Does the customer have an evaluation board for the ADV7180?

    -Matt

  • 0
    •  Analog Employees 
    on Aug 2, 2018 2:28 PM
    This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

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    EZ Admin