Syncing a percussion loop with a live band recording

[FrankM]

I'm back... with a new problem - one that I suspect can be solved with DP's beat detection and time-correcting tools, however I've never done anything like this. I'm on a deadline, so rather than experiment, I thought I'd ask here as there might be a certain way to get this done that I might not discover for a while.

During a live show, there was supposed to be a percussion loop started that would be in the house PA and extra loud in the drummer's monitor. Listening to this loop, he would count in the band and play to the loop; the band then plays to him. That has worked in the past, but this particular time - where the show was being recorded, of course - the monitor board had a hiccup and the loop was almost inaudible. The drummer signaled to kill the loop, then the band played the song without it. No loop, no click, nothing to keep the band at an exact tempo except the drummer's skill (he did a great job, which might make what I'm asking about easier).

I am wondering if I can take this loop, which is two-bars long, add it to the project, and have it stay in time with the drummer. I've already put it on a track, lined up the start, then did a Command-R to repeat it 20 times, but of course it goes out of sync with the live drums pretty quickly. Once the loop starts, it has to keep going for five minutes.

I assume I'll have to take the drummer's audio - kick drum? Snare? A submix of everything? - and do a "find beats", then this gets translated into a tempo map that I apply to a 5-minute-long audio file of the two-bar loop I create. Is this right? All I know right now is to drag the top edge of a soundbite to time-expand or compress it, giving me the idea to do this piecemeal, with separate two-bar-long soundbites of the loop, adjusting as I go - i.e., when I start to hear drift I insert another soundbite of the loop and drag it to match the drums, repeat, etc... this seems like it would be a very long process! There must be a better way, I hope - can anyone help? Thanks a ton!

[EDIT - I just want to make it clear that, at least at this moment, I am not looking for step-by-step instructions! AAMOF I just checked my DP prefs and "Automatically analyse beats and tempo" is checked - so I'm already partly there, I think. Just a general description of how to make this work in the most efficient way would be a godsend - I think I can figure out the details!]

[Phil O]

If you have already found the beats you can create a tempo map for the conductor track. Select the the soundbite and go to Audio>Soundbite Tempo>Adjust Sequence to Soundbite Tempo. I'm pretty sure that will create a tempo map. You may need to be in conductor track mode first. I'm not sure.

I've found that finding beats is sometimes a little flakey and you have to go in and do a lot of editing. If you have that problem, record a track with a single click on each beat while listening to the performance. The click can be anything - cow bell, hand clap, claves - whatever is easiest to play in time and just get a single hit per beat. When you find beats in that track it should be 100% on.

Your friendly neighborhood Phil

[FrankM]

Thanks Phil. I'm gonna make a dupe of this sequence, or maybe just copy the one song needing the loop to a new sequence, in order to experiment. One thing I didn't mention is that this show was also filmed, so our work will have to be synced up to video at some point. In the past, I've seen where adjusting sequence to soundbite tempo changes the location of things on the timeline; I just wonder if that might have any implications for the video. What I really want (I think!) is to conform the percussion loop to what's already in the sequence, without changing anything else.

Oh yea - not sure if this matters, but the entire show was recorded into Pro Tools at its default tempo (120 bpm), so the bars & beats (and tempo) in DP have no relation to the music at all.

[Phil O]

When you create the tempo map it should be independent of that 120. I think.

I've had issues with ProTools files before and tempos. I can't remember the details but I do know we worked it all out. It IS doable. Don't get discouraged.

[HCMarkus]

Lock the audio tracks so they stay put relative to timecode.

[FrankM]

Thank you, that's something I probably would have missed. Much appreciated.

[FrankM]

I got it done in kind of a brute-force way. Using the kick drum track (a section of which was playing perfect quarter notes), I got a tempo ("Analyze Soundbite Tempo"), which of course was an average, as the drummer was not playing to a click. I brought that kick track plus the other drum tracks into a separate sequence, then copied the kick track tempo to that sequence via the menu selection "Adjust Sequence to Soundbite Tempo" (can't do it on the original sequence, as all my MIDI notes' timing relative to the audio changed - gotta leave that alone!). Then, I imported the loop and did the reverse with that soundbite: Adjust Soundbites to Sequence Tempo. This processed the soundbite to a new tempo that matched the average tempo of the kick drum.

I repeated this newly-processed soundbite of the loop a few times to create a 16-bar long loop, then merged all the soundbites into a single soundbite. I lined it up with the first kick drum and let it rip. By the end of the 16 bars there was some drift, which I expected. Looking in the sequence editor, I could see the original drum tracks' transients, so I clicked on the top right of the loop soundbite (the "grabbing hand") and dragged the end of the soundbite forward or backwards a little to time-shrink or stretch until I could see the transients of the loop line up with the live drums. This worked! It wasn't perfect, as our drummer is a human being, so there were a few spots not in perfect sync - but it's certainly close enough. Anyway, I repeated this process for all of the following 16-bar long sections until I got to the end of the song.

I guess I am still a little curious to know if there's an easier (read: quicker) way to get this done, but right now I'm happy I made it through this phase of fixin'! There's more to do.

[HCMarkus]

(can't do it on the original sequence, as all my MIDI notes' timing relative to the audio changed - gotta leave that alone!).

If you locked the MIDI Tracks they wouldn't shift with tempo changes. Sorry I did not mention that before; I didn't realize you had MIDI involved in the live recording project.

Locking tracks is something used a lot in film scoring... keeps audio and events lined up with picture.

[FrankM]

Thanks, this is good to know for the future. I guess I've never been in a situation where I needed to know about or use track locking. I just looked it up in the user guide, there it is on page 130 - a short and sweet description that explains all. A very useful setting!