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Combining ANALOG video feeds -- real time/low latency

We fly fpv. One pilot, one second operator controlling the camera, both have analog video feeds.

Pilot vtx feed: backgrond gimbal feed: we want a small rectangle in the corner overlaying the pilot's background feed

requirements: real time, as we fly FPV, added latency < 20 ms ideally

Which (ready made) hardware would allow this? The inputs are AV out (we can convert to any plug).

Should be portable and battery powered, ideally.

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You'll need an analog DVE. They aren't really manufactured anymore, but you can probably find something used. If you don't need to resize the overlay video, you might be able to get away using an analog switcher with a mix/effects bus and applying a wipe.

No matter what, you'll need to frame sync the two feeds. That will add at least one frame (33ms) of delay. A DVE might add another frame on top of that.

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  • Thx! Do you have a particular brand and model in mind? This usually makes it easier to find websites, suppliers and other related info than general search terms like DVE. Not sure how we gonna frame sync, as both signals are coming from different receivers.
    – babipsylon
    Jun 1, 2022 at 20:28
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    The only brands I'm remembering right now are Abekas and Pinnacle. There were definitely others, but those are probably the two you are most likely to find on used broadcast equipment sites. As for the signals coming from different receivers, that is exactly the purpose of frame syncing. You need to have both sources time-aligned so that the DVE can manipulate the video without rolling or glitching. The signal flow will be receiver -> frame sync -> DVE. Jun 2, 2022 at 14:29
  • Are both signals delayed by 33ms, or only one of the 2 feeds is adjusted to run in parallel and synced with the other, so only one is delayed? Is it possible with very specific hardware to have maximal one frame delay (< 35ms)? Maybe with some custom chip that is hardcoded to do this (not a DVE)? Or first a digital conversion?
    – babipsylon
    Jun 11, 2022 at 14:47
  • What is the analog switcher option exactly?
    – babipsylon
    Jun 11, 2022 at 14:48
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    Let's continue this conversation in chat. Jun 11, 2022 at 17:34

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