Multiple Blackmagic capture devices on Macbook Pro

Man on a quest here ... to make a robust multi-cam system on a 2020 Macbook pro.


The question I have reached is - can I successfully run 2 UltraStudio Recorder 3G capture devices into the same laptop running Wirecast and enjoy stability? If yes, can I push it to three?

Some background on the journey to here ... 


I was running a Magewell SDI capture into a 2013 USB 3 macbook, on a switched feed from a Roland V1 SDI. All good, but I’m now a run-and-gun streamer so looking for faster setup and less load to move in and out. 

I Recently got a 2020 Macbook, which is Thunderbolt 3 ports - so had to convert the Magewell from USB 3 to USB C. I then added two Magewell HDMI capture devices - also USB 3 on converters for a total of 3 inputs. 

Unwittingly, I had unlocked the gates of hell. 

I started with Livestream Studio as Vimeo give it away. But a lot of crashes and some weird problems. The biggest was the audio from the HDMI sources (cams 2 and 3) becoming confused. Sometimes cam 2 carried cam 3 audio - sometimes they switched over. Sometimes there was no audio.

This was sorted on Magewell advice to change the HDMI sources to identify by serial number instead of generic name - it seems the Mac was having trouble mapping them properly, as this did indeed solve the audio issue. 


Magewell also said they don’t recommend attaching more than one of their devices to the same USB bus. I’m still not sure if my 2020 MB has just the one, or more than one .... ? 

So I went back to two cameras - one on SDI and one on a HDMI device.

But I still had crashes and found studio buggy, so paid to use Wirecast - which I have never regretted. Awesome tool. 

I started with 2 cameras and got that working. So full of bravado I added back in camera 3, which worked - until it didn’t! Often it would work fine, but on a bad day I’d have Freezes, stuttery vision and audio sync issues (like 50 seconds out!). I’ve literally had clients in tears on bad days. 

So I went back to two cams again and seem to be able to make that work reliably. But I really need 3. 

I thought about again using my Roland V1, but that takes away some flexibility I need if I run all cameras through it. My Sony Z280 delivers its SDI signal about 100 milliseconds faster than my GH5s, which is turn about 40 milliseconds faster than my plain GH5 (about 3 frames at 25fps which is just enough to show).


I cant correct for this on the Roland but can in Wirecast (I believe) if I bring the Sony in via the SDI capture and bring in the two GH5s via the Roland (already switched between cam 2 and 3). 

But that’s a bit of an awkward workflow. I’ve now spotted a Roland 2 channel switcher called a v-02, which you can operate via a footpedal! It is much smaller and easier than the V1 and looks suited for a 2 input world with 3 cameras. But I’m trying to figure out if that is my best option. 

I’m still using those same Magewell devices - and I eye them off with suspicion. I don’t like the old USB running through converters but I’ve had no alternate devices to swap in for testing. 

However, the Blackmagic Recorder 3G looks like it Is worth a try - and I could buy 3 for the cost of one Magewell! On face value, stepping up to a thunderbolt 3 connection has to be a better world than USB 3 converted to C. 

I saw in a recent post that CraigS mentioned these, and his opinion carries weight around here! So I’m about to order 2 - or should that be 3?


My ideal world is 3 capture devices feeding 3 cameras into Wirecast with no freezes, crashes or problems. 

Will the Blackmagic recorders give me that?

Thanks for joining me on my journey!

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  • Unless the power availability on the ports and the need by Blackmagic devices has changed, there is likely a limit to using to BMD UltraStudio Recorder G. Only two may work due to power requirements. The third can be Magewell though. Both ioGear and ATEN make an HDMI to USB-C device that supports up to 1080p60. It seems there's a similar device from Pengo as well. We haven't tested them so we don't officially support.

  • Caution - that setup with three devices can only be used while using a TB3 dock that also provides power. With only 1 TB3 port left, you won't have room for a USB input or en external monitor. Do not run power through a dongle.

      • CraigSModerator
      • Telestream Desktop Forum Moderator
      • CraigS
      • 3 mths ago
      • Reported - view

      Mickey Carson Good tip. Do you have a preferred TB3 dock you've used?

      • Mickey Carson
      • Mickey_Carson
      • 3 mths ago
      • Featured
      • Reported - view

      CraigS I've been using a caldigit unit and it has been handy. Provides power and a bunch of connectors from one TB3 port. I haven't tried more than 2 mini recorders, but I do run 2 of them with a mini monitor at the same time. It may help that I run the monitor on the caldigit's TB port.

  • Mickey Carson said:
    I've been using a caldigit
     Mickey Carson said:
    I do run 2 of them with a mini monitor at the same time.

     Thanks for that. That would mean that using the dock allows for three Ultra Studio devices. That the dock is powered likely alleviates the TB bus power limit.

  • CraigS Hey Craig - those Blackmagic recorders are in short supply here in Australia, but I'm hoping to have them to try out in the next few days. 


    I'm really leaning toward only using two capture cards - one using my Roland V1 to make a sub-mix of the two cameras next to me at the rear of the venue and one feeding in the wireless (Bolt) camera from front and mobile. I might even end up with all my cameras on the Roland if I need to run a monitor out (which I talk about below). 


    I've built up from a single source testing streaming recording and sync as I went and everything seems solid in that dual configuration. The problem with the third input - in my previous experience - is that it will work fine, until it doesn't. I've done several jobs in a row with 3 and all was well - but boy, when it goes bad it goes really bad. (I don't think this is a Wirecast problem - I reckon its the hardware). 


    While I have you ..... 


    I've been streaming off a single 4G/5G modem - which sometimes gives me 400 down and 80 up! But the cursed thing drops out and I go offline, so I am going to have to go to a bonded system - I've just ordered a Teradek Vidiu go with the nodes to give me three networks at once. 


    But it makes using Wirecast harder - I think? I want to keep it in my workflow as it is great mixer. 


    I saw a post from you from a year or so back saying it might be possible to send a clean Live window to the multiviewer for feeding into an external encoder - anything more you can tell me about doing that? The people who sold me the Vidiu are suggesting a Blackmagic Ultrastudio Monitor would do the job?



    • Craig Saunders One problem with using the multiviewer, if you pop into another application, like email to retrieve a stream key, your multiview will dissappear sometimes. I used to use it regularly and other than that and the resource usage, it worked just fine. 


      One thing you will find using the BMD output is that the audio does not sync up with video. Lip sync is off when using a typical audio interface or analog output. You have to use the embedded audio on the BMD out if you don't want to add delay in your mixer. This has caused me a little distress because of everywhere I distribute this feed in my work flow. Not all of my destinations can use the embedded audio. 


      I should ask CraigS if they understand this problem and might have a solution inside the box such as providing delay to an individual output instead of globally to the program. I dont want to put delay in the program because it seems to affect the stream output as well.



  • Craig Saunders said:
    I saw a post from you from a year or so back saying it might be possible to send a clean Live window to the multiviewer for feeding into an external encoder

     The recommended workflow would be to use Wirecast Pro Blackmagic (or AJA) video out but you can set Multi-Viewer to Live Broadcast Out only. Audio would be using monitor (not live) out since Wirecast would be sending a feed for monitoring. The computer would be using the GPU out to a device it thinks is a monitor. Using a GPU that has an HDMI out port is best. Given the GPU is involved with other tasks that it may prioritize sometimes there can be minor issues. Because so much of this is really system specific it's hard to get too specific other than to test and see if the results are good (or good enough).

    • CraigS Hi Craig. I had not seen the pro option for the BM monitor - that would be the way for me to go (and I have one on its way). 


      I tested out my Roland V1 to sub-mix 2 cameras but it got a bit weird and I need to explore that further.


      So Ideally, I would bring each camera in (3 max) on an individual capture device as that gives me the most flexibility with everything on one platform. 


      But I'm running out of ports! I start with 4 TB3/USB-c ports on my Macbook - but one goes for power. That would leave 3 for capture - but only 2 if I have the monitor out. And I may need to bring a mixer in direct over USB-C. 


      I have one of the Caldigit TB3 hubs that Mickey was talking about staring at me right now - hooked up to my Imac. So I'm hopeful that might be the solution. 

       Mickey Carson  please feel free to jump in with any advice on your configuration. 


      I will soon have five capture devices to choose from, from which I need to make 3 work at the same time: 

      1 x Magewell SDI 

      2 x Magewell HDMI 

      2 x BM recorders (still in the post) 


      I will also have the BM monitor, to feed out into a Teradek Vidiu for encoding and transmission. And I have a Sound Devices mixer, which I'd like to bring in over USB-C as a source.


      And I need to get power in - which looks like it will always be plugged direct to the laptop (as it needs 100w)? I also need to work out how to power the Caldigit from battery as I sometimes work away from power - I have D-tap and USB-C power banks that output 100W. 


      On my first look I'm thinking: 

      Mac port 1 - power in 

      Mac port 2 - BM monitor 

      Mac port 3 - Magewell SDI 

      Mac port 4 - Caldigit T3 hub


      Then on the Caldigit there are 2 x Magwell HDMI inputs (USB3) and the mixer (USB-C) 


      That would make me soooooo happy! 


      What do you think? 

    • CraigS Hey Craig - I may be thinking of this the hard way.


      I've just found a thread from you in 2017 that might have the answer (you must feel like you are living Groundhog Day with the same questions over and over)


      I like the idea of this - a Sonnet Tech Thunderbolt 3 enclosure with three Blackmagic decklink mini recorder 4k PCI cards. 


      That looks like 3 cameras in with my choice of SDI or HDMI. 


      Have you had any further experiences with that setup since you first mentioned it in 2017? 



    • CraigS Thank you.

      • CraigSModerator
      • Telestream Desktop Forum Moderator
      • CraigS
      • 2 mths ago
      • Reported - view

      Mickey Carson You're welcome of course.

    • CraigS No, the output via a BMD mini monitor. My lips are synced on my stream and on a mulitiview out,, but the bmd output is not unless I use the embedded audio which is synced. I am sending that out to a number of destinations and I cant always use that embedded audio. I have to add delay to the audio in my mixer, but it is not consistently the same value.

  • Mickey Carson said:
    the output via a BMD mini monitor.

     Please clarify. Wirecast Pro Video Out? Wirecast Pro Video Out uses Wirecast's Live Output audio. Multi-Viewer out is not reliable for downstream integration.

    • CraigS Yes. Pro video out via BMD mini monitor.

      • CraigSModerator
      • Telestream Desktop Forum Moderator
      • CraigS
      • 2 mths ago
      • Reported - view

      Mickey Carson Can you send that directly to an external recorder for a recorded example?
      Also do a Wirecast Output Record to DIsk MOV recording so there's a reference to compare it to. That will show us internal processing versus Video Out.

  • Update ... I believe my quest may be over! 

    huge thanks to CraigS and Mickey Carson for their insights - they held the answers I needed. These forums are very useful. 

    So ... I am now running 3 cameras to a macbook pro and a BM video monitor to a Vidiu Go with bonded connection. It encodes H264 720p 25fps very nicely. 

    My macbook ports are:

    1. Power

    2. BM monitor 

    3. Magewell SDI Usb

    4. Caldigit T3 hub with one Magewell HDMI and one BM recorder (and an external mixer via 3.5mm plug) 


    At idle, with live icons, CPU is about 8% - hitting record for a high res .mov only bumps it up to around 12%. 

    in my tests so far this system feels rock solid, without even a hint of any ‘let me think about that’ moments. In effect, I have removed many of the places where Wirecast has to interact with the Mac architecture leaving it to just ... work! 

    So happy .... thanks guys!

    • Craig Saunders That Caldigit should handle your power too...

      Like 1
      • CraigSModerator
      • Telestream Desktop Forum Moderator
      • CraigS
      • 2 mths ago
      • Reported - view

      Mickey Carson Thanks for that. Very useful information.

    • Mickey Carson Hey Mickey - I don’t think that will work for me as the Caldigit only delivers 87w and my 2020 Macbook draws 96w. But I will run some tests this week. 

      When I had 3 Magewell USBs hanging off it, an mp4 recording running and streaming the laptop would lose charge even when plugged into the mains! I have USB C power bricks that hold 28500 milliamps and deliver 100w and this setup would drain one of those dead in 45 minutes. 

      I need a full battery setup as I am often away from power. I have a 100w delivery 240v battery pack that would fail running the Macbook but I’m hoping might run the Caldigit ok. But ideally I would like to plug the caldigit to a d-tap vlock battery or one of those USB c power banks - but its plug looks to be unique to that unit. 

      And an update - I used this setup yesterday for a 2-hour stream and it was flawless! 

  • I'm glad that configuration is working for you, Craig. I know it's a pain to get everything up and running and not crashing!

    I'm pretty sure that all Thunderbolt 3 docks are limited to 87W, as it was the max that was agreed upon when the specs were ratified. I think there's an article on the Caldigit website that I read about it.

    If the dongles ever become a problem here's my solution: I went with a Sonnet Echo Express SE1 Thunderbolt 3 enclosure with a Decklink 8k Pro capture card. I've got up to four sources that I can capture at once, and it works great. I have my 2019 16" MBP connected to two external monitors (extra screen for me, and a screen for the talent to see the Wirecast live output), the TB3 enclosure (I have a USB C hub connected to the TB3 passthrough on the enclosure for Ethernet), and also my power brick. My cameras are connected via SDI to the capture card. The initial investment was a bit pricey, but I'm really happy with how solid it's been working.

    I've seen other setups with a 3 slot Sonnet enclosure completely packed with capture cards, so I know there's plenty of room for expansion with a single MBP.

    Happy streaming!

    • David Kazebeer Hey David .... Thanks for the feedback! 

      I feel a bit like that freshly trained soldier who arrived green into a combat they thought they were prepared for, but were not. But I'm much more combat-hardened now - and I've ditched the equipment (and software) that didn't help me. Been an interesting journey .... 

      I'm right there with you on the Sonnet - if I was starting from new, I would get one of those and pack it with 3 cards (4 cameras in on one, monitor out on another and an audio card)! That would cost about $2,200 Australian dollars - versus the $2,100 that 3 x Magewell and 2 x BM recorders have cost. But even if I upgrade to a Sonnet the dongles are still useful for smaller gigs - and they give me the basis of a second crew in the field for days when I might be double-booked (because that is the dream!).  

      Like 1
  • Interesting challenges maneuvering around the limits of TB ports on MBP which is going to be even more interesting with Apple Silicon.

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