I have two recordings of the same song and want to mix them together. The problem is, that the tempos of the two songs are not exactly the same and also not completely constant because the songs were recorded without a click. Now I want to keep one song as it is and adjust the tempo of the other song in such a way that they match perfectly together.
My idea was to somehow mark in both songs about 10 keyframes which belong to the same position in their song respectively. Then audacity should just change the tempo of the second song in such a way that the marked keyframes of the second song coincide with keyframes of the first song. Is that or something similar possible with audacity?
Beat matching is a feature request.
If the pitch of both versions is correct, use Effect > Change Tempo to make the length of one song the same as the other. You may need to make fade ins and fade outs the same length on both songs before using Change Tempo.
What is the purpose of mixing the two versions? Do you want to blend different equalisations together? It may be better to just EQ one version.
The purpose is that in the different recordings different people are singing the song but I want them to sing it together. Of course I tried something like looking how long both versions are and calculating the tempo diff I have to apply. But in this case only start and end match together and the part in middle doesn’t fit anymore. I could do such an adjustment for shorter time intervals repeatedly. That would give a quiet good result. But it’s much work to do this manually. Therefore I was asking for an appropriate method. Such that I only have to mark the start of certain bars (maybe one out of four) and audacity calculates itself the appropriate tempo stretching factor and applies it.
Audacity does not do what you want in an automatic way. That’s why I said it was a feature request.
You may be able to do Effect > Change Speed on one or more tracks and then Change Tempo on other tracks to that new length.