Dual Stream capture : 4k ?

Hello,
I am building a machine for dual SDI stream capture, from 2 Micro Studio Cameras 4k.
The decklink duo 2 explicitly supports 2 simultaneous cameras capture in HD (and the quad, 4 cameras).
- But does Blackmagic provide a solution to capture 2 cameras simultaneously in 4k?
(Decklink 4k Extreme states "dual link" (commutable) but not "dual stream" (2 simultaneous cameras)...)

I have 2 use cases :
- one is realtime live projection of 2*4k streams using my own softwares (using gpu shaders and storing 8bits RGB images in RAM)
- and the other being the post production (edit/grade/comp) of prores HQ 10bit log 4k footage stored in the atomos, and copied on the computer (not realtime).

I will use 2 blackmagic micro studio camera 4k recording prores HQ 4k in an atomos Shogun Flame (because it supports SSD and HD down conversion of output while recording 4k).
The atomos SDI loop out will be plugged in a decklink card.
I wrote a software suit to accumulate the 2 camera inputs, composite, and send it to a projector.
I just need to add support for blackmagic devices using the sdk.
The Shogun Flame can down rez to HD if necessary, so i can plug its SDI loop out in the deckling duo 2 SDI ins. But having the ability to use 4k signal would be usefull specially for backgrounds.
Please can you confirm that none of the 4k PCIE cards from blackmagic do dual stream capture ?

For the workstation, i will use
- a supermicro 7048 R-T workstation with X10DRI serverboard
- 2*Intel Xeon E5-2620 v4, Broadwell-EP, 2.1Ghz 8 Core/16 Threads, 3Ghz Turbo
- 8*16GB samsung DDR-4 2400Mhz registred ECC RAM
- for the system drive 1*Intel SSD DC P3500 Series PCI-E, 400GB, 2200MBs read, 1000MBs write
- for the data drives 2*HGST Ultrastar 4TB 7K6000 enterprise, SATA III, 128MB, 7200rpm - 512N
- mirrored in software RAID1
- for the OS MS windows 10 64bit pro
- 1*NVIDIA PNY GEFORCE GTX 1080TI 11GB GDDR5 PCIE 3.0
- 1*4K LCD IIYAMA 28" screen
- 1*DLP FULL HD 3100 LUMENS OPTOMA projector

The audio signal going realtime in my inhouse looper software will use 4 HF microphones.
There is no analog audio XLR i/o on decklink duo 2, so i need to use 2 XLR inputs on each atomos (but that's another company, sorry), and have the audio coming in the sdi ins as well.
So my audio software also needs to use decklink SDK to use audio from SDI capture board.
(I originally planed to add an RME fireface 8in/8out audio usb2 card but gave up because it would be out of synch.)

About the video assist 4k, i gave up because i don't see HD down converter, nor support for 256BG SD cards (without dropped frames). The stage performance often goes over an hour so i guess we need to record on SSDs.

Thank you very much for your advises!
best regards...
Julien

No, the multi stream cards are only 3G-SDI. You can use multiple Decklink cards to capture multiple 4K streams.

Technically top end cards (eg. DeckLink 4K Extreme 12G) may be able to do it. Not out of the box, but if you are programmer you should be abel to access it in SDK. This card has 2 separate channels A/B, so it maybe possible to use them independently (there is enough bandwidth for 2x UHD 10bit 4:2:2 streams at 60fps). This is really question to BM support.

thank you for your advises.
I realised that Micro studio camera 4k has rec709 video color profile (contrasted, ungradable image) locked on the sdi output.
But, according to Andy from BMD support, this can be changed to log film color profile from the atem protocol, using either atem or BMD Arduino cards (I'm waiting for confirmation before i buy it!).
I need to take a decision today for the camera, between GH4, with VLOG, and the potential problems of overheating sensor (we'll be shooting continuously for 3 hours), and Micro studio cams with this hack.
I must say i do not feel very reassured since no one reported to be working in log with Micro studio 4k cams.
I can do the arduino dev, or take an atem production studio 4k to change this film/video (rec709/log) parameter (and others) in the BMMSC.
On the other side, GH4R looks better for lowlight, has vlog color profile (and is a very nice camera overall), only the heat problem is a concern.
Do you have any advise on this decision?
PS:
For the 4k dual stream capture, support confirmed that i can do it with mutiple decklink cards. Though for audio, it cannot be done in separate softwares since audio capture cannot be done independently of video capture.

Yes, dual cards will work (but also creates other issues if you want perfect sync), but it's shame you can't use extreme model and have 2 channels independent inputs (I'm almost sure AJA and BlueFish444 offer such a mode).

I'm not sure about cameras- don't have enough experience. Funny enough I've accidentally noticed today in one of the videos that some cameras offer HDMI only preview with internal recording turned off (e.g. Sony a6300 which does overheat a lot). I'm not sure if GH4/5 have such an option, but they tend to overheat much less, so if you could also turn off recording I think you should not experience overheating issue with GH4/5.

Actually:
http://cdn.videodevices.com/download/gu ... GH4MFT.pdf

by setting HDMI output to 10bit you will disable internal recording, so this will minimise overheating for sure.
I think I would prefer one of the Sony cameras over Panasonic (specially for low light and look), but we know they overheat more, although again- you can turn off internal recording which may be solve it.
I would buy from the source where I can easily return them, just in case

thanks,
we will do long running shots like 3 hours * 3 times a day.
I read so many warning from users saying that it can damage the sensor...
On the other side i read GH4/5 got special attention for this issue, for film shooting.
I'd like to find real heat tests on long shots.
And some details about studio cams : I guess studio cameras have a fan to cool the sensor ?

Proper video camera should have no problems with 3h (at least in theory).
With still cameras I assume this is not necessarily the case- they are just not designed with idea of video recording for eg. 5H. Interesting problem

The best thing to do is not to buy a camera but rent one and test it.
I use both, micro 4K and GH4. Panasonic definitely has better low light and dynamic range. I run GH4s all day with no heating problems what so ever (2 hours - 4 hours continuous recording)


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thanks you for giving your experience, that's very valuable.
I just received a precision from support

Hi Julien, no the MicroStudio 4K has no ability to do film/log color profiles. This functionality is only available on the Studio 4K Camera.

Kind Regards,

Cameron