Pocket 6K Multicam Gen Lock Sync ?

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vivoices

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Pocket 6K Multicam Gen Lock Sync ?

PostTue Aug 13, 2019 9:02 am

Can I sync lock multiple Pocket 6ks / 4Ks with a Tentacle Sync E or Ambient NanoLockit on each camera and on the Zoom F8?

In my current multicam setup I sync via audio. Every camera receives wireless scratch audio from the recorder.
Resolve does a very good job at syncing the video and audio sources.
But since the cameras are free running and NOT locked to TC, I often get a time difference of up to a half frame between the cameras.

Is it possible to sync multiple Pocket 6ks / 4Ks like a gen lock in a studio, so the frames within each camera are always starting to read out at a common synchronisation point?
Udo Jansen

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John Brawley

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Re: Pocket 6K Multicam Gen Lock Sync ?

PostTue Aug 13, 2019 9:54 am

vivoices wrote:Can I sync lock multiple Pocket 6ks / 4Ks with a Tentacle Sync E or Ambient NanoLockit on each camera and on the Zoom F8?

In my current multicam setup I sync via audio. Every camera receives wireless scratch audio from the recorder.
Resolve does a very good job at syncing the video and audio sources.
But since the cameras are free running and NOT locked to TC, I often get a time difference of up to a half frame between the cameras.

Is it possible to sync multiple Pocket 6ks / 4Ks like a gen lock in a studio, so the frames within each camera are always starting to read out at a common synchronisation point?


Yes, if you have an external TC source, you can jam sync them, though the audio input. I'm not sure how accurate they are over time as I haven't tried it yet. Perhaps Kris will let us know.

JB
John Brawley
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vivoices

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Re: Pocket 6K Multicam Gen Lock Sync ?

PostTue Aug 13, 2019 10:03 am

Hi John,
I know about the jam-sync option.
2 question to clarify what I mean:

Do the cameras sync to the external TC and ignore their internal clock as long as the external TC generator remains connected?

Is the start of each frame read-out is triggered by the external TC or is the external TC just embedded in the metadata but frame read-outs are still triggered by the internal clock?
Udo Jansen

Win 10 Pro 1903, Resolve Studio 16.1 b1, Dual 6 core Xeon @ 3.5GHz (24 threads), 96 GB ECC RAM, Nvidia Quadro P4000 (8GB VRAM) 431.70 NSD, 10TB SSDs, Intensity Pro 4K | Nuendo, Wavelab, RX
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John Brawley

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Re: Pocket 6K Multicam Gen Lock Sync ?

PostTue Aug 13, 2019 10:11 am

vivoices wrote:
Do the cameras sync to the external TC and ignore their internal clock as long as the external TC generator remains connected?


Yes.

vivoices wrote:Is the start of each frame read-out is triggered by the external TC or is the external TC just embedded in the metadata but frame read-outs are still triggered by the internal clock?


Yes.

Once you record the it's an internal frame count.

It sounds like what you're really wanting to ask is,

can the camera be synced to external reference, for sub frame accuracy in the use of 3D or VR rigs.

The answer I think here is no. It's only TC sync-able, not "genlock" or Ref" lockable.

The UMP G2 for example has "ref" in for this purpose. I am guessing though, hopefully i'll be corrected if that's not the case.


JB
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vivoices

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Re: Pocket 6K Multicam Gen Lock Sync ?

PostTue Aug 13, 2019 10:20 am

Thanks John,
synced for sub frame accuracy as used in 3D or VR productions is what I am asking.
Udo Jansen

Win 10 Pro 1903, Resolve Studio 16.1 b1, Dual 6 core Xeon @ 3.5GHz (24 threads), 96 GB ECC RAM, Nvidia Quadro P4000 (8GB VRAM) 431.70 NSD, 10TB SSDs, Intensity Pro 4K | Nuendo, Wavelab, RX
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John Brawley

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Re: Pocket 6K Multicam Gen Lock Sync ?

PostTue Aug 13, 2019 10:24 am

vivoices wrote:Thanks John,
synced for sub frame accuracy as used in 3D or VR productions is what I am asking.


Phase lock ?

Then I would guess no.

JB
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vivoices

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Re: Pocket 6K Multicam Gen Lock Sync ?

PostTue Aug 13, 2019 10:36 am

Perhaps someone from Blackmagic can give a definitive answer.
Udo Jansen

Win 10 Pro 1903, Resolve Studio 16.1 b1, Dual 6 core Xeon @ 3.5GHz (24 threads), 96 GB ECC RAM, Nvidia Quadro P4000 (8GB VRAM) 431.70 NSD, 10TB SSDs, Intensity Pro 4K | Nuendo, Wavelab, RX
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rick.lang

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Re: Pocket 6K Multicam Gen Lock Sync ?

PostTue Aug 13, 2019 3:38 pm

I believe BMD has only referred to LTC Timecode sync which will be frame accurate with Tentacles left on each camera which is how I’ll be running, and on the external recorder as well.

They have not mentioned phase-locked at all which is quite different.


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Rick Lang
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vivoices

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Re: Pocket 6K Multicam Gen Lock Sync ?

PostTue Aug 13, 2019 4:47 pm

Rick,
LTC timecode, as I understand it, is a remnant from the analog video tape when LTC and VITC were common and today generally used as a synonym for timecode as an audio signal.
VITC btw was recorded for each frame as a, sort of, additional scanline before the first scanline of each frame, so that was phase accurate.

But Grant clearly talks about timecode information as metadata when he refers to the sync bin in the latest "Post Production and Camera Update" video.

My hopes are still up that we might get phase accurate sensor read-outs when feeding perfectly synced external TC to the cameras and recorders.

Can someone from Blackmagic please clarify?
Udo Jansen

Win 10 Pro 1903, Resolve Studio 16.1 b1, Dual 6 core Xeon @ 3.5GHz (24 threads), 96 GB ECC RAM, Nvidia Quadro P4000 (8GB VRAM) 431.70 NSD, 10TB SSDs, Intensity Pro 4K | Nuendo, Wavelab, RX
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Denny Smith

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Re: Pocket 6K Multicam Gen Lock Sync ?

PostTue Aug 13, 2019 5:19 pm

There is one way to find out, rent two cameras and give it a go (test). ;)
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Denny Smith
SHA Productions
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vivoices

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Re: Pocket 6K Multicam Gen Lock Sync ?

PostTue Aug 13, 2019 6:04 pm

I agree, Denny.
But I will go for multiple Pocket 6Ks anyways, so I will find out eventually.
The first 2, that someone else ordered before me, will arrive at my supplier's next week.

It would be great though to know beforehand and from a verified BMD source.
Udo Jansen

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Re: Pocket 6K Multicam Gen Lock Sync ?

PostWed Aug 14, 2019 6:26 am

As I guessed, no. No genlock / reference video.

I asked.

JB
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Re: Pocket 6K Multicam Gen Lock Sync ?

PostThu Aug 15, 2019 5:08 am

Grant said that the cameras start drifting from an initial jam sync after about one hour.
Tentacle and Ambient have a drift of about one frame after 24 hours.

So when I shoot a 6 hour festival, I get several frames of difference in the footage of 2 continuously rolling cameras, but they will have accurate TC metadata.
That would be kind of odd.
Resolve will sync according to TC. What will Resolve do with the extra or missing frames?
No problem of course with the cameras that stop recording every now and then.

If the internal clock and frame read-out is triggered by external TC, it still might not be phase accurate, but frame accurate and no drift underneath the TC metadata.
Udo Jansen

Win 10 Pro 1903, Resolve Studio 16.1 b1, Dual 6 core Xeon @ 3.5GHz (24 threads), 96 GB ECC RAM, Nvidia Quadro P4000 (8GB VRAM) 431.70 NSD, 10TB SSDs, Intensity Pro 4K | Nuendo, Wavelab, RX
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Re: Pocket 6K Multicam Gen Lock Sync ?

PostThu Aug 15, 2019 3:35 pm

vivoices wrote:Grant said that the cameras start drifting from an initial jam sync after about one hour.
Tentacle and Ambient have a drift of about one frame after 24 hours.


My understanding of this is quite limited, and I have no actual experience with it, but from a bit of digging I did out of curiosity after I saw the use of these timecode devices, it looks like if you have multiple such devices synced to each other, you can leave them constantly connected to the cameras to keep the cameras synced to the device, which should in theory correct for that drift after the first hour? I believe that might at least give you TC metadata accuracy to match that of the devices themselves?
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Re: Pocket 6K Multicam Gen Lock Sync ?

PostThu Aug 15, 2019 3:55 pm

Yes, as long as all devices are sync’d to the same master clock source.
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Denny Smith
SHA Productions
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Re: Pocket 6K Multicam Gen Lock Sync ?

PostThu Aug 15, 2019 4:04 pm

The cameras have an internal clock that is a basis for triggering the frame read-outs.
According to the answer in this topic https://forum.blackmagicdesign.com/viewtopic.php?f=2&t=96762 they also have a separate internal clock for audio.

It is possible to jam sync the cameras, meaning that you connect an external TC generator for a short time, so the internal clock sets itself to the exact time of the external TC.
If you do this with multiple cameras, their internal timecode is in sync, which is very useful for multicam editing.
But the stability of the internal camera clocks allows the multiple cameras to stay in sync for only about an hour without having an external TC generator connected.
So you can sync multiple cameras for about one hour with only one external TC device.

If every camera has, say, an Ambient NanoLockit permanently connected, their timecode stays in sync for as long as the NanoLockits are in sync and connected to the cameras.
The external timecode should take over the internal camera clock.

If this is also true for the internal audio clock would be interesting to know.

One question that remains is, if the cameras could be close to being phase locked if the external TC sync is VERY precise.
Udo Jansen

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Pocket 6K Multicam Gen Lock Sync ?

PostThu Aug 15, 2019 6:06 pm

Timecode with Tentacles constantly on camera and external recorders will not drift during your shoot. The master Tentacle can be set from your phone (which provides time from an atomic clock every time you boot); then the slave Tentacles follow their master. On a very long shoot—you know those punishing long days, you could always reset the Tentacles every few hours to ensure they are all giving the same signal.

But that is not the same as a genlock signal. That may not be perfect either, but everything genlocked would follow the same imperfection so no issue as I understand it. Haven’t thought about genlock since the 80s with the Amiga and Newtek.
Rick Lang

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