Halve MIDI note durations

Hi all,

in a large MIDI multitrack project, what’s the best way to halve all MIDI note durations on all tracks?

I remember that in Rosegarden there were the “Rescaling note durations” functions

For example:
Adjust->Rescale->Halve Durations
Adjust->Rescale->Double Durations

or even to rescale a region by a quantity of your choice:

Adjust->Rescale->Stretch or Squash…

Maybe you can do the same thing in Ardour with the MIDI/Transform function?
(I haven’t succeeded yet…)
If so, can anyone tell me the right setting for example to halve the durations of all MIDI notes in a region?

Thank you,


You are right, it can be done with the MIDI transform tool:
Select all the MIDI regions then right click > Selected Regions > MIDI > Transform.

Then, set:
Set [length] to [this note’s] [length],
then click the blue “+” button and set the second line:
[ / ] [exactly] [2]
Click “Transform” and you’re good to go.

(the result is : Set length to the considered note’s length divided by 2)


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Thank you.
I did a test on a short section following those steps.
This is the original:

This after the transformation:

But I wanted to get this result instead:

Is there a way to do this?

You can do a second pass of the transform tool, this time with the [start time] instead of length.

Clarifying : Set [start time] to [this note’s] [start time],
[ / ] [exactly] [2]


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Yes, it works fine now, thanks.
It’s a bit cumbersome, with two consecutive steps.
Is there a way to automate this procedure? (like recording a macro)

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