While you can set the timecode of the ATEM using the ATEM SDK the ATEM Software Control Panel (on ATEM firmware version 8.0 or higher), setting the timecode this way is not as accurate as a true jam sync. The generated timecode tends to be off by as much as a second from the start time entered. So it isn't anywhere near accurate enough to do frame level matching of different sources.
I was hoping that even if the ATEM Constellation couldn't read continuous timecode, it would be possible to do a software jam sync of the ATEM via the SDK. So you could use an audio input of the computer to read LTC timecode and use it to do a onetime sync of the ATEM's internal timecode generator. And then depending on the accuracy of the internal timecode generator it could easily be several hours before there is a frame of drift.
Unfortunately setting the ATEM timecode via the SDK doesn't seem to be quick enough to make this work, as the initial sync right after setting the timecode is off by a variable amount, for reasons that are unclear. More on that here:
viewtopic.php?f=4&t=92836I really wish they would allow using one of the audio inputs as a timecode source. This would be useful on all of the ATEM models that lack dedicated timecode inputs, not just the Constellation.