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Latency (preferably glass-to-glass) ADV7482

Category: Datasheet/Specs
Product Number: ADV7482

Hi,

I was reading the thread  [ADV7482] Time (Latency) from input to output of Video.. However, it is not clear to me how much glass-to-glass latency  I can expect. I would like to implement the following system:

  1. A SoC receives on its CSI interface and using the adv7482 the video of an external source outputting via HDMI.
  2. The SoC receives the video, ecnodes it and immediately passes it to a network pipe.
  3. The SoC transmits the video via LAN to another network end.

I want to estimate the glass-to-glass latency. I know approximately my SoC can encode HD video at around 50ms, and the network conditions are good, which will not introduce more than 10ms. The above mentioned thread says 100ms is expected from input to output with HDMI. Then, my glass-to-glass latency would be expected at >150ms? After reading that this latency when a camera is connected via CSI to a Jetson Nano can be around 60ms. I am doubting that 100ms is a realistic value. Has somebody tested this or have an idea about how low to expect?

Thanks

Wladimir

  • Hi,

    This you need to evaluate based on your own system requirements and also need to consider the external factors like  connected sink/display's.

      Please note that, It also depends on the controller that we are using. If customer want the exact result then the customer can use the API's to measure the exact time (i.e In Software customer can add the api like GetCurrentMsCount(); between the appropriate locking registers to get the exact locking time).

     Also delay depends on what options are turned on in the video path.

    Thanks,

    Poornima

  • Hi,

    Thanks for the reply. In fact, I have already estimations of the external factors. What I want to discard is that the ADV7482 introduces such a high latency HDMI to CSI that the other factors are negligible. An approximation of typical delay of this chipset for HD resolution would be helpful. What are the options that can affect the delay on the video path?

  • Hi,

    As per expert comment "CP core has approximately 8 -12 clock cycles delay. This varies slightly depending if color space convertor etc. is used.

    DVI input would add approximately 10 clock cycles to the CP core delay when using a DVI/HDMI input.

    3D comb adds no delay to the video signal , the filtering is done on a old frame of video compare with the current frame.

    2D comb adds 3Line delay for NTSC and 5 line delay for PAL inputs".

    Please refer expert comment about ADV7842 latency atRE: ADV7842 Latency Questions [ADV8003 used as well] 

    Thanks,

    Poornima