HOW TO: Use multiple devices to have multiple in and out

As explained in this article, the best way to have multiple inputs and/or outputs on one Mac is to use one video device that has the number of inputs/outputs that you need. But sometimes, that device may not exist, or for some reason you want to reuse devices that you already own.

 

Different combinations

With our applications we don't limit any combinations so you can use:

  • multiple identical devices (for example connect multiple AJA Io T-Tap)
  • multiple devices from the same brand, but different model (for example a Blackmagic-Design UltraStudio Mini Monitor with a Blackmagic-Design UltraStudio 4K)
  • multiple devices from different brands (for example a Blackmagic-Design UltraStudio Mini Monitor with an AJA T-Tap, and an M|44).

At the time of writing, we don't know of any incompatibility issues between devices or drivers, but this is something that we can not guarantee will always be. Indeed, this is something that is handled by the devices manufacturers. They usually guarantee that multiple identical devices will work fine. If it's a different model, it may be more difficult to get the guarantee, but once you say you want to mix with a different (competitive) brand, then you never can have that guarantee.

So it is up to you. You can get in touch with the device manufacturer and/or us to check if there are any known issue, but you'll understand that we can't validate every single combination that may exist.

 

How is the order of the devices maintained?

If the devices that you connect are different (different model or brand), then it's easy, and we can always identify each of them. But when you connect multiple identical devices, we will append a number to each of them (1), (2), ... and we must be able to identify which one is which across restarts of the application, so the output/input 1 is always the same device. If the device has a unique identifier it is easy, but if it does not have one, it can be tricky.

 

For devices that have a unique identifier

Most video device have a unique identifier (kind of its serial number). All AJA and M|family devices have a unique identifier. Only some Blackmagic-Design devices have that identifier.

When you configure OnTheAir Video, OnTheAir CG, OnTheAir Node, or MovieRecorder, we store in the preferences that unique identifier so we are always sure to output/input using the correct device.

This means that for example if you own 2 AJA T-Tap, if you connect both of them, every time you will restart your Mac, or MovieRecorder, even if you change the way they are plugged in Thunderbolt to your Mac, every time the configuration will remain and we will output to the correct device.

But this also means that for example if you connect  one of them to your computer and configure it, it will work fine. But then later on you forgot which device was connected and connect the other AJA T-Tap, the preference will show that the device is <Missing> as it does not have the same unique identifier.

 

Devices that don't have a unique identifier

At the time of writing, only all 4K devices (UltraStudio 4K, Decklink 4K ...) and the DeckLink Mini Recorder have that unique identifier. For these devices, the order of inputs and outputs will always remain the same and will behave as explained above. For example, if you connect multiple UltraStudio 4K to your Mac, and start MovieRecorder, the input number 1 and input number 2 will always correspond to the same device.

For the devices that do not have a unique identifier, the order of the devices is set by the way they are connected to the Mac. So as long as you don't plug or unplug anything new in the Thunderbolt connectors (or change the order of the PCI cards), the devices order will remain the same.

But let's say you have 2 UltraStudio Mini Recorders, if you start MovieRecorder, and configure your 2 sources, in MovieRecorder, they will be named "UltraStudio Mini Recorder (1)" and UltraStudio Mini Recorder (2)". If now you connect an external hard drive to your computer and restart MovieRecorder, both device will most probably show as <Missing> and you will have to select them again and make sure to select the good one knowing that their order may have changed. This is because the configuration of your Thunderbolt buses have been changed, and thus now there is no way for us to identify which device is which.

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