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daveyijzermans  
#1 Posted : Saturday, August 4, 2018 5:00:42 PM(UTC)
daveyijzermans

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Hi!

I'm still awaiting the release of the Magewell Flex 4 input/2 output card, and wondering if I should order it. I currently have a Blackmagic Duo 2 card and haven't been able to actually try a Magewell card ever before.
Wondering if there's anyone here that can measure the difference between capturing with Decklink and capturing with Magewell (preferably with and without the "Low Latency capture" option in vMix)
I'm hoping even for an improvement of 2 frames, but as of now I know nothing yet: haven't found other information online and my local resellers also don't know.

Thanks in advance if you're able to test this for me.

Kind regards,

Davey.
zenvideo  
#2 Posted : Monday, August 6, 2018 7:28:31 PM(UTC)
zenvideo

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daveyijzermans wrote:
I'm hoping even for an improvement of 2 frames, but as of now I know nothing yet: haven't found other information online and my local resellers also don't know.

I shouldn't think you'll get a two frame improvement because I don't believe that either card (Magewell or Blackmagic) contributes as much as two frames of latency at the capture stage, so there's not a 2+ frame capture latency there to be eliminated. At best (in theory) the low-latency mode can reduce latency in progressive signals by almost a frame (or by almost half a frame for interlaced signals). As for the Flex I/O cards, samples were first introduced at IBC last year, but I have no word as to when they will be available. Hopefully more news will be forthcoming at IBC in a little over a month. I believe that there's been a bit of a rethink on the internal design which has caused the delay.
mjgraves  
#3 Posted : Tuesday, August 7, 2018 12:07:26 PM(UTC)
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I may be worth mentioning that there are certain limits to reducing latency. In a traditional broadcast chain there may be zero latency. That implies that no device in the chain has to frame sync the video. It further implies that all the devices are genlocked to a common reference.

If a source is not genlocked the device receiving the signal must resync it, which introduces a frame of delay.

I've noticed that when creating complex composites in vMix there amount of latency may also increase as the layering gets more complicated.
JoseL  
#4 Posted : Wednesday, August 29, 2018 7:07:09 AM(UTC)
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On my tests basically same latency with magewell or blackmagic. In fact i think blackmagic has less latency with progressive signals than magewell, difficult to measure because is 1f or less difference.

Genlock do nothing for capture and is not needed. Asap signal is comming it is captured and processed, no need to sync with others. Genlock is for blackmagic output, to send signal at same "time" than other signals when it comes to a switcher or mixer, that way you will get one less frame on the mixer input.

In my test "low latency mode" and normal mode same latency... maybe i need more complex compositions...

regards,

Jose.
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