Cubase: Tempo Warping (Saturday 12 August, 2023)
Many live recordings are not recorded with a click track (metronome), which can be used to keep the drummer and band in time. Consequently, the tempo might slightly fluctuate over time. Moreover, if you load the song into a DAW like Cubase, it will not be aligned with the grid. This is not a problem per se, but if you want to complement the song with MIDI tracks, or want to add a drum VSTi like Superior Drummer then it really helps if the song nicely lines up with the time grid (bars, beats) of the DAW.
The alignment of a song with the DAW grid is called Tempo Warping and is explained in an excellent video of Greg Ondo:
Video: Greg Ondo (Steinberg) explaining tempo warping.
Based on the video of Greg Ondo, I explain the concept of time warping for a specific project that I am working on. The starting point is a mp3 of a live recording of Madelyn Dee, a Dutch blues, rock, pop, jazz band. Prior to the tempo warping in Cubase, I unmixed the mp3 in different tracks (vocals, drums, bass, guitar, and piano) using SpectraLayers 10. The unmixing is not perfect but very acceptable as a starting point to create a backing track to re-record the vocals and add VST instruments and/or re-recordings of the other instruments. These tracks, including the original mp3, I load into Cubase.
Step 1. Tempo detection. I used the drum track for the tempo detection. This will generate a tempo track showing the (fluctuation of) tempo across the song, and a time signature track that defaults to a meter of 1/4 (Image 1). For this particular song the average tempo is about 120bpm. There is a tempo jump at the start of the song, which I will correct manually.
Image 1: Unmixed tracks loaded into Cubase using a track coloring scheme that I use across all my projects. The generated Signature and Tempo track are shown on top of the mp3 (reference) track. Here, I already changed the meter to 4/4 and deactivated the tempo track (see next steps)
Step 2. Set the time signature. In the video the signature is set to 4/4 meter at the first down-beat of the song. Since the song I am working on starts on a down-beat, I simply change the default meter from 1/4 to 4/4. When playing the song the click track follows the changes in tempo.
Step 3. Apply the tempo track to the audio files. First select all audio files. Then go to Audio –> Advanced menu and choose ‘Set definition from tempo‘. Select “Save Definition in Project Only” and select “Set all Tracks to Musical Time Base”. This will adjust the audio tempo to the project tempo. In addition, it will set all audio tracks to ‘musical mode’ to tempo-match the audio to the project tempo.
We can now turn off the tempo track (i.e., set Fixed Tempo Mode) and set the tempo by typing in the value on the Transport Panel. I set the tempo to 60bpm, which will now play the song in this tempo.
I also shift all audio tracks to align them with the Cubase tempo grid (bars and beats).