I have been struggling to accurately add in a metronome track to an existing recording due to the original not being in strict tempo. The average beats per minute can easily be worked out and the metronome track added either via Generate > Rhythm Track in Audacity or by recording a new track from my Roland drum kit metronome (using the voice count). Invariably having lined up the start of the piece using the Time Shift Tool, I find the tempo can fluctuate throughout the rest of the recording. Using Effect > Change Speed allows me to make a selection and either extend or reduce time, but it really is fiddly.
What I was wondering is can selections be made (perhaps even a bar at a time) and just the selection stretched or shortened by, say, picking up one end and lining it up with the metronome click one a second track much like Time Shift works. That way it would be possible to periodically pull the recorded track in line with the metronome beats to correct any ‘wandering’. Thanks for any suggestions.
I don’t know if there’s a better way, and this is time-consuming, but this is what I do on the click track, after creating it and getting it to the right tempo as close as I can:
Wherever the beats begin to not line up, I click the mouse between two beats, hold shift down and press the left or right arrow key to select a tiny sliver. Usually pressing the arrow key twice does it. Then Ctrl-x to cut it. Now you have just removed a sliver of time, just on the click track, to move it back. When you used Ctrl-x, you also have a copied sliver of time you can use to add between any two beats that need to be stretched out. Click the mouse between two beats and press Ctrl-v and you have just stretched the time to the next beat. If you need more space, right click to get out of paste mode, and press Ctrl-v again. You can repeat, as needed.
I do this multiple times, as I listen a bit at a time and match the beats all the way through, accounting for all the places the tempo fluctuates.