My kick bounce is slowly going off the grid over a long period

[DBK]

Not sure whats going on.

I have a midi track for my Kick body and a midi track for my Kick top. I have them both bussed to an AUX track where I have some compression to bring them together. Now I need a ghost kick for the sidetrain trigger so I sent the aux track to a bus then offline bounced the bus. Everything prints as expected and it bounces/imports me a new audio track with my single kick waveform. Only problem is when I repeat kick over 100 bars or so it SLOWLY goes off the grid. Which makes no sense to me? Im bouncing in grid, everything in grid mode. The single bar selection that I bounce is definitely a bar, no less no more. Confirming this all in grid mode. But when I bounce it LOOKs fine at first. But if I duplicate it for 6 minutes throughout the session, by the end its noticeably off if i zoom in.

The only difference between this bounce and my usual bounces are that im bouncing from an aux track hosting the 2 midi tracks. Wheras I usually just have my kick on one midi track with no AUX track as a host. Still doesnt make sense. I know what im doing in regards to bouncing and keeping everything on the grid, etc..thats why this is confusing me. Makes no sense why it seems to be drifting off the grid.

[DBK]

Here is the region edge only 2 bars in- zoomed in as far as PT will take me, both edges are flush.

Now im also attaching a screenshot of the region edges when I duplicate it all the way to 200 bars. Zoomed in all the way again. So a VERY slight drift. But it will make a difference in how my sidechain reacts over time. I just edited all the starts by hand to be on the grid but im still curious why its doing this.

[Stig Eliassen]

This could be sample rounding errors. If you haven't tried it, what happens if you select (click'n'drag in grid mode) the 1 bar kick with the Selector tool, then execute the duplication process?

[YYR123]

Delay comp?, well I guess all the kicks would be off then huh, nvrmd

[Carl Kolchak]

Originally Posted by DBK

Here is the region edge only 2 bars in- zoomed in as far as PT will take me, both edges are flush.

Now im also attaching a screenshot of the region edges when I duplicate it all the way to 200 bars. Zoomed in all the way again. So a VERY slight drift. But it will make a difference in how my sidechain reacts over time. I just edited all the starts by hand to be on the grid but im still curious why its doing this.

That's Sample Rounding.

Obviously, in a 44.1kHz session, there are 44100 samples that make up 1 second of time.

But how many MIDI ticks correspond to 1 second?

It depends on the tempo of the song, and also if there are any tempo changes.

Because there is no direct correlation between samples, and ticks, and because Pro Tools is sample accurate, making all it's time based calculations based upon absolute sample values, under certain circumstances you will find that Pro Tools places a duplicated region / clip at it's technically correct sample location (the MIDI position has to rounded off to the nearest sample - it's not, as some believe, that sample are being incorrectly placed), rather than the less accurate tick position - which is actually where you wanted it to be.

So what might be rounded off to the nearest sample in one repetition, may become an increasing drift away from the tick based grid, as that original rounding off is repeated over a greater length of time.

Once you understand this, you will see how to force Pro Tools to make the appropriate decisions when repeating material.


In your screen shot, the audio track containing your bounced kick drum is set to Samples, as it's timebase.

This should be changed to Ticks.

Another thing to know is that Pro Tools behaves differently depending on how you select the material you wish to repeat.

If you just grab it, and use the "Duplicate" option, you will most likely get sample rounding.

If instead you make an edit / timeline selection, Pro Tools will accurately repeat the material based upon the grid (Bars & Beats most commonly).

Using the Loop tool also adheres to the grid, as does using "Repeat", rather than "Duplicate".

[DBK]

Thanks guys I got it.