Thank you for your answer. Crossfade would be too simple. Transitions must be as inaudible as possible. That means the tempo of e.g. two songs must be the same and the beat must be aligned. You also need loops and effects to connect different genres with each other.
In my DJ program Serato, the songs are already stored with a beatgrid that absolutely fits the beat. Too bad that the tempo tag (ID3-bpm) is not read out when importing. It would be even better if you could take over the beatgrid, which is already stored in the ID3 tag. That would speed up the remix and much more.
I don't think so, because that's not only crossfade ?