Cameras are no longer synchronized after many hours

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Fralalà

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Cameras are no longer synchronized after many hours

PostWed Aug 10, 2022 8:41 am

Hi everyone!
I've been reading you for a long time but I just registered because I have some questions!

Premise: I use different cameras: Sony, Panasonic, sometimes mirrorless, etc ..

I broadcast live sporting events, for example pole dance (so there is a stage). Sometimes, after many hours of streaming (12, 15 hours) the cameras are no longer "synchronized" with each other and when I switch from one camera to another there is a time jump.

My configuration:

1. Camera with HDMI output
2. Micro Converter Blackmagic HDMI to SDI or Bidirectional (we have several)
3. SDI cable
(This varies for each camera, from 20 meters to 70 meters)
4. Blackmagic DeckLink Duo2


Obviously, if I turn off for a moment, the cameras immediately go back to being synchronized. This is a very economical solution and I can turn them off at breaks but it is not the solution I like. :lol:

How can I synchronize the cameras? I read about the Genlock. Could Mini Converter Sync Generator be the solution? How to use?
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Xtreemtec

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Re: Cameras are no longer synchronized after many hours

PostWed Aug 10, 2022 3:40 pm

I'm not sure what you mean with time jump??

Also cameras with HDMI do not have Genlock capabilities. At least not when using HDMI. Genlock often only can be found on cameras with SDI outputs.
Daniel Wittenaar .:: Xtreemtec Media Productions ::. -= www.xtreemtec.nl =-
4K OBV Trailer, ATEM TVS HD, 4M/E Broadcast Studio 4K, Constelation 8K, Hyperdeck Studio 12G, Ursa Broadcast 4K, 4K fiber converters with Sony Control
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Howard Roll

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Re: Cameras are no longer synchronized after many hours

PostWed Aug 10, 2022 4:18 pm

12-15 hours without reference
Xtreemtec wrote:I'm not sure what you mean with time jump??

Also cameras with HDMI do not have Genlock capabilities. At least not when using HDMI. Genlock often only can be found on cameras with SDI outputs.


The OP is using a decklink for capture so at frame 1,080,000 one cam might be 9 hours 57 seconds, and the other might be 10 hours, and 2 seconds. When reset, the cameras are close again until the drift again accumulates to noticeable levels.

Yeah, without reference the cameras are going to drift.

Good Luck
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Fralalà

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Re: Cameras are no longer synchronized after many hours

PostWed Aug 10, 2022 4:20 pm

Xtreemtec wrote:I'm not sure what you mean with time jump??

Also cameras with HDMI do not have Genlock capabilities. At least not when using HDMI. Genlock often only can be found on cameras with SDI outputs.



By time jump I mean that if the athlete makes a jump and I have 3 cameras, at the same time in two cameras he is in the air, in the other instead, he still has to jump so when I change camera during live streaming, this thing can be seen quite a lot of.

Isn't there a device, or a way to sync all video streams? With external devices or from the Blackmagic DeckLink duo2 menu?

I searched online but didn't find much.
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Fralalà

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Re: Cameras are no longer synchronized after many hours

PostWed Aug 10, 2022 4:22 pm

Howard Roll wrote:12-15 hours without reference
Xtreemtec wrote:I'm not sure what you mean with time jump??

Also cameras with HDMI do not have Genlock capabilities. At least not when using HDMI. Genlock often only can be found on cameras with SDI outputs.


The OP is using a decklink for capture so at frame 1,080,000 one cam might be 9 hours 57 seconds, and the other might be 10 hours, and 2 seconds. When reset, the cameras are close again until the drift again accumulates to noticeable levels.

Yeah, without reference the cameras are going to drift.

Good Luck



Exactly! that's just what happens!

Obviously the "cheapest solution" is to turn the cameras off and on (even immediately) in turn but I was wondering how to solve this from a technical point of view. Turn on / off I don't think is the correct solution, even if it works :lol:
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Fralalà

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Re: Cameras are no longer synchronized after many hours

PostWed Aug 10, 2022 4:26 pm

Howard Roll wrote:12-15 hours without reference
Xtreemtec wrote:I'm not sure what you mean with time jump??

Also cameras with HDMI do not have Genlock capabilities. At least not when using HDMI. Genlock often only can be found on cameras with SDI outputs.


The OP is using a decklink for capture so at frame 1,080,000 one cam might be 9 hours 57 seconds, and the other might be 10 hours, and 2 seconds. When reset, the cameras are close again until the drift again accumulates to noticeable levels.

Yeah, without reference the cameras are going to drift.

Good Luck


Obviously, if I turn off for a moment, the cameras immediately go back to being synchronized. This is a very economical solution and I can turn them off at breaks but it is not the solution I like. :lol:
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ManchesterV

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Re: Cameras are no longer synchronized after many hours

PostWed Aug 10, 2022 4:33 pm

It's almost certainly a software issue BUT it could be hardware related (but not a Blackmagic fault).

Are you using OBS or similar for capturing/streaming?

What spec is the host computer?

Are using a desktop computer or a laptop with a thunderbolt enclosure?
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Fralalà

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Re: Cameras are no longer synchronized after many hours

PostWed Aug 10, 2022 5:12 pm

ManchesterV wrote:It's almost certainly a software issue BUT it could be hardware related (but not a Blackmagic fault).

Are you using OBS or similar for capturing/streaming?

What spec is the host computer?

Are using a desktop computer or a laptop with a thunderbolt enclosure?



For now I have tested the thing on OBS and on Wirecast, Vmix would be missing but we are getting along very well with OBS for the way we are working on these events.

(In other events we use Vmix so I might test this too)

We have two ways to use the DeckLink Duo 2 card (we have two):

- Desktop PC with: 16GB of Ram, i9-9900K, RTX 2070 8GB and Decklink Duo2 of course.

-Startech chassis with Decklink Duo2 connected with Thunderbolt 3 to a computer that can be a Mac with M1 processor or a Santech R39 (i7-7700K 4.20Ghz, 24Gb Ram, GTX 1060)

For now this problem has been seen during sporting events where we used the first computer but only after many hours of live streaming.
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Xtreemtec

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Re: Cameras are no longer synchronized after many hours

PostWed Aug 10, 2022 5:39 pm

I can not imaging HOW a camera can Drift multiple frames as in it is getting slower and slower to push live image out of its port.. Meaning it would buffer the image somewhere inside the camera??? :lol:

It's probably your decklink card / Software causing frame delay as an internal process of the PC.

Also be aware that IF you use different cameras the latency from camera to camera will always be different.. This is because the consumer cameras / DSLR cams HDMI output is not build for real LIVE purpose.. it is a monitoring port.. There will always be latency and this latency is in every brand and model different.

Broadcast optimized cameras are purpose build to get Live image as fast as possible out the SDI port. without too much latency.. Because else the camera would never work for IMAG work..
Daniel Wittenaar .:: Xtreemtec Media Productions ::. -= www.xtreemtec.nl =-
4K OBV Trailer, ATEM TVS HD, 4M/E Broadcast Studio 4K, Constelation 8K, Hyperdeck Studio 12G, Ursa Broadcast 4K, 4K fiber converters with Sony Control
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Fralalà

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Re: Cameras are no longer synchronized after many hours

PostWed Aug 10, 2022 6:17 pm

Xtreemtec wrote:I can not imaging HOW a camera can Drift multiple frames as in it is getting slower and slower to push live image out of its port.. Meaning it would buffer the image somewhere inside the camera??? :lol:

It's probably your decklink card / Software causing frame delay as an internal process of the PC.

Also be aware that IF you use different cameras the latency from camera to camera will always be different.. This is because the consumer cameras / DSLR cams HDMI output is not build for real LIVE purpose.. it is a monitoring port.. There will always be latency and this latency is in every brand and model different.

Broadcast optimized cameras are purpose build to get Live image as fast as possible out the SDI port. without too much latency.. Because else the camera would never work for IMAG work..


Do you think it could be a problem with the capture card?
But then I would have to turn off the card, not the cameras to solve the problem.

I started making live streams in 2019 and I still don't have that much budget to buy all cameras the same, so they are different. We manage to arrange the colors making them look the same without too much trouble.

Isn't there a way, something, that can control the frame synchronization of the cameras even if they are different?
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Howard Roll

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Re: Cameras are no longer synchronized after many hours

PostWed Aug 10, 2022 7:04 pm

I imagine the buffer is happening in the PC. A referenced time base corrector would keep the cameras in real time but frames would necessarily be duped or dropped. You could genlock the output of the Decklink but I imagine the problem is because the decklink outputs are sync’d so there’s a disparity between input and output frames between cams.

Solutions may include using discrete capture cards, A TBC/frame sync, or perhaps using an Atem SDI to re-sync.

Good Luck
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Xtreemtec

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Re: Cameras are no longer synchronized after many hours

PostWed Aug 10, 2022 8:41 pm

I think disconnecting the SDI from the capture card and reconnecting will reset it's input buffer and clear up the latency. ;)

I dont think you need to power down the camera
Daniel Wittenaar .:: Xtreemtec Media Productions ::. -= www.xtreemtec.nl =-
4K OBV Trailer, ATEM TVS HD, 4M/E Broadcast Studio 4K, Constelation 8K, Hyperdeck Studio 12G, Ursa Broadcast 4K, 4K fiber converters with Sony Control

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