I recently completed a seamless Atmos album mix with crossfades - the process was a bit convoluted. I had to export individual ADMs I mixed with the crossfades in place, joined them in Dolby Atmos Conversion Tool, re-imported to check the crossfades were good - which they were not. There was a short gap between each song. I thought this was maybe a Nuendo issue.
I fixed the issues and exported the full ADM for blu-ray and individual ADMs for digital.
As a test, I took the individual ADMs I knew were correct and joined them again using the tool to see if the gaps would re-appear. Low and behold, they did. Here’s a grab of my bed zoomed in where the crossfade occurs:
I just did a bit more testing - I imported the first two ADM files to check that the start and ends were as expected, which they were. I joined them using the tool and the gap appeared. So to confirm, the Dolby Atmos Conversion Tool is not seamless as far as I can tell…