Differences between "Virtual Output" and "Direct Link"

That’s a common misinterpretation (even amongst our team) of 2 different features. We often have the question of wether the Direct link will work without Virtual Output. So here is the explanation of the differences between the 2.
Differences between a Virtual Output and the Direct Link
Virtual Output
A "Virtual output" is something that you can use as a "playback device" in any of our playout applications when you don’t have a physical output. Either because
  • you are running tests and don't have the hardware yet,
  • you use OnTheAir Video or OnTheAir Node together withy MovieStreamer HLS to stream to the web, so you don't need a physical video output
  • you use the direct link between OnTheAir Video and a Live input of OnTheAir CG Server.


As you can see you won't need any video device for streaming. But if you want to have a real video output out of OnTheAir CG Server, simply add a video device as output there, and that's it.

Direct Link
The “Direct Link” is what allows one of our application running on the same Mac to access the frames that are outputted by one of our playout application (OnTheAir Video, OnTheAir Node or OnTheAir CG Server). Here are common uses of this feature:
  • run OnTheAir Video (or OnTheAir Node) and MovieRecorder on the same Mac. You can see OnTheAir Video as a source in MovieRecorder in order to record what is going out, or even simpler have a preview. We have a short video showing that.
  • run OnTheAir Video (or OnTheAir Node) and MovieStreamer HLS on the same Mac. You will be able to stream directly to the web.
  • run OnTheAir Video and OnTheAir CG Server on the same Mac. In OnTheAir CG Server preferences, you can then add OnTheAir Video as a "Live Source", and then simply overly graphics on top of that signal, without the need of a video card with keying.



All our playout applications support the "Virtual Output", but not all support the "Direct Link"

Software Virtual Output Direct Link
OnTheAir Video Express  Yes No
OnTheAir Video Yes Yes
OnTheAir Node Yes Yes
OnTheAir CG Yes Yes
M|Replay Yes No

This means that for example OnTheAir Video Express can not be used for web streaming application only. You would have to use a "real" video output to playout, and then a "real" video input to retrieve the signal in OnTheAir CG Server or MovieStreamer HLS. But all can happen on the same computer still.


Example of use

For web streaming only, with no "real" video output

If you are streaming to the web and need animated graphics, you could use the following workflow.

As you can see there is no real device:
  • in OnTheAir Video, select the "Virtual Output" in the playback settings
  • in OnTheAir CG Server, create a "Live" item  to use the signal from OnTheAir Video through the direct link
  • in OnTheAir CG Server, select the "Virtual Output" in the playback settings
  • and finally choose "OnTheAir CG Server" as the source in MovieStreamer HLS. The signal will be sent through the direct link

As you can see it is a combination of virtual output and direct link that allows you to do that.


With "real" video outputs 

You can use the Direct Link with a physical device (AJA, Blackmagic-Design, M|Family) or with a Virtual Output. Thus it is completely independent from the Virtual output. This means that in the example above, instead of any of the Virtual output, you could have used a real video output. If you use real video outputs for everything, you could have the following workflow:
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