How to Change Tempo Without Stretching MIDI?

[Thomas Happ]

I have a project that I've been importing audio of various BPMs and changing the tempo to match.  Somehow, I ended up with 190 bpm even though it should be 95 bpm.  I *thought* that the way around this was to change the tempo, select all, then Process->Length and stretch Start Times and Durations by 50%, but when I do that, the midi notes seemingly stretch out of the clips - like the clips aren't following the notes and the notes go outside of them?   Not only does it look bizarre but the notes no longer play.  I provided before and after screenshots to show what I mean.

I found that if I bounce all my clips and then stretch, it works, but I have lost all my careful linking of clips that I use to make sure when I change one, I change them all.

[David Baay]

See the solution I gave two threads down in this forum:

- Set the Now time at Measure = current tempo +1 (191).

- Shift+M t to open Set Measure/Beat At Now.

- Enter target tempo +1 (96) for Measure, Beat 1 and OK.

- CbB will change the initial tempo around existing MIDI (and audio of present) without altering its absolute playback timing

 

 

[Thomas Happ]

18 minutes ago, David Baay said:

See the solution I gave two threads down in this forum:

- Set the Now time at Measure = current tempo +1 (191).

- Shift+M t to open Set Measure/Beat At Now.

- Enter target tempo +1 (96) for Measure, Beat 1 and OK.

- CbB will change the initial tempo around existing MIDI (and audio of present) without altering its absolute playback timing

 

 

Thank you so much, this MOSTLY works, probably close enough for me.  

I discovered there seems to seems to be some kind of ordering or floating point error where the first note of some clips get cut off; they have the same starting time (in the interface) but it detects the note as starting outside the clip (before and after shown in these screenshots).  I'm thinking that when it divided the start time in half the clip start ended some tiny fraction ahead of the note but so small it doesn't the time difference in the interface. The workaround is to stretch the clip slightly to the left, causing the note to reappear, and then put it back (with snapping on so it goes to exactly the measure start).

Probably preaching to the choir I feel like this is really non-intuitive and there should be a checkbox or something next to the tempo to fix clips/events while you adjust it.

 

[David Baay]

Hmmm... yes, I can imagine that might happen at certain tempos based on other cases I've encountered of MIDI events being unexpectedly suppressed by 'mis-aligned' clip boundaries . This should be reported to the Bakers. Can you share a portion of the project file that demonstrates the problem? Or myabe just give a specific example of  an event at time xxx:xx:xxx that doesn't get played after changing the tempo by this method.

[David Baay]

Just now, David Baay said:

Hmmm... yes, I can imagine that might happen at certain tempos based on other cases I've encountered of MIDI events being unexpectedly suppressed by 'mis-aligned' clip boundaries . This should be reported to the Bakers. Can you share a portion of the project file that demonstrates the problem? Or myabe just give a specific example of  an event at time xxx:xx:xxx that doesn't get played after changing the tempo by this method.

EDIT: Incidentally, I have reported many times over the years that setting a MIDI clip's Timebase to Absolute should lock its absolute duration as well as its start time. Contrary to the Ref. Guide (last time I looked), it currently only locks the start time.

[Thomas Happ]

41 minutes ago, David Baay said:

EDIT: Incidentally, I have reported many times over the years that setting a MIDI clip's Timebase to Absolute should lock its absolute duration as well as its start time. Contrary to the Ref. Guide (last time I looked), it currently only locks the start time.

Oh yeah, I did notice that.  

Oh!  And one more thing - if do the Shift-M trick, and then use Undo, it sets everything back, except any notes that disappeared remain disappeared.  So it seems that "Undo" doesn't truly save project state so much as perform the math in reverse.

I've since gone and cleaned up the file so I'm reluctant to try and  mess it up on purpose again.  But I found also that this problem happens to the end of the clip - notes that I previously cropped out past the end of the clip by shortening it sometimes appear again as a tiny sliver at the end.