What do you do when you want to add ACID loops to a live song? The problem with live music is that is usually not performed to a “click-track” and the tempo drifts so that the ACID Beatmapper cannot be used. The answer is simple. What you need to do is something I call “Tempo Mapping”. Unlike beatmapping which adjusts the tempo of the song to match the project, tempo mapping adjust the tempo of the project to match the changes in the live feel of the song.
To do this:
- Add the song to your project as a One-Shot (this is important because you don’t want ACID changing the tempo of the song). If the Beatmapper dialog comes up when you add it, just dismiss it.
- Set the tempo of the song to roughly match the song. This particular song is around 125 BPM
- Next drop a Tempo Marker (T) at each measure if the song. These temp markers will be used to map each measure to match the live feel of the song (hence the term “tempo mapping”)
- Play the song and tap the H key on each downbeat (the H key drops a Time Marker) If your timing is a little off, you can go back and adjust them later to be sure they land right on the downbeat. If you do, use the Shift key to avoid snapping as you move.
Let’s take a moment to visually see what is happening here. Look at how the distance between the Tempo Markers which are set to the first beat of each measure, and the Time Markers which are the actual downbeats drift further apart over time. You can actually see the tempo drift!
- Here is where the magic happens. Place your cursor at the Tempo Marker, Right-click the Time Marker and Select “Adjust Tempo to Match Mark to Cursor”. This adjusts the tempo of the previous tempo marker so that the time marker (the downbeat) matches the cursor (which you placed at the start of the measure).
Now your downbeat starts at the beginning of the measure. Repeat this for all of the temp markers. Place the cursor on the tempo marker, right-click the time marker, and select “Adjust Tempo to Match Mark to Cursor”.
Notice that your finished project now has a new tempo for each measure which brings the downbeat at the start of the measure.
The reason this works is because Time Markers mark “wall-clock” time or “absolute” time and Tempo Markers mark “relative” time of the beat. What you are saying is that you want the absolute time of the downbeat to match the relative beginning of the measure. The “Adjust Tempo to Match Mark to Cursor” function in ACID is a powerful and often overlooked feature that can make easy work out of mapping songs with temp drift.
Happy Editing,
Johnny “Roy” Rofrano
Thank you for this thorough explanation and excellent tutorial. As a remixer who specializes in odd mash-ups and the like, I frequently draw source material from the pre-digital era. Using this technique (as opposed to hundreds, or even thousands of edits) is a great way to keep the “swing” of live performances intact while constraining the performance to the steady tempo required to add loops.
A few additional notes for users of this technique – firstly, disregard the waveform display when adjusting the tempo. I was frequently second-guessing my sense of rhythm when the display of downbeats were not matching up after the tempo adjustment. The other note I have is aimed at remixers – if you want to incorporate the finished product into a remix wherein you will want to further change the overall tempo, you can simply render the project as a wave. If the addition of the time changes in the display bugs you, you can re-render that wave in a tool like Audacity to get rid of them, leaving you with a song file that holds a steady tempo and can be looped, tempo-shifted, etc.
Thanks again – I was going a little nuts trying to incorporate Fred Astaire’s recording of “Puttin’ On The Ritz” into a mega-mix. Over 100 splices and it still sounded like junk. Using this technique keeps Fred and the band in time while keeping the “swing” that makes the song so likable after all these years.
Thanks for the tutorial. All these people doing mashups with drum machine music have got it made with the beat mapper wizard in Acid. I agree with the person above – for live music remixes/mashups you need to use other means…. this info really helps after trying to find the answer all over the .net THANKS.
this is also very helpful for tempo drift in ACID Pro…
http://www.youtube.com/watch?v=PWIkWx76yKo
This solved a *huge* problem that I had from a recording from the 1970s that I made without a metronome – beats went from 96 to 121 BPM. Put it perfectly back in time. It sounds great now. Thanks!
Thank you so much John Rofrano for explaining this in a thorough, step by step manner! I’ve been trying to do this for years!!!! I want to just be able to play guitar with a natural/dynamic tempo and then have the bars/loops line up to the original recording so I can add loops so it sounds organic and not robotic. Thanks a gain for you generosity! you are the man!!!!
Thanks,
Rob McMann
This works, but it takes forever… I have songs in which I have to manually place 400 markers! Please tell me there is a quicker way. I can’t believe sony won’t allow you to just tap it out and then automatically stretch each measure.