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Old 06-14-2017, 12:03 PM   #1
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Default Recorded Midi Events Have Wrong Start Time When Changing Tempo While Recording

When I record a midi performance (midi coming in through virtual midi ports) and have a CC linked to SetTempo, when I change the BPM via the CC, Reaper puts midi events recorded after the tempo change on the wrong time offset relative to the midi item start time.
This screws up the timing of the recorded midi events (it also overwrites earlier events with later events etc.) and thus makes the recorded midi unusable.
(Btw, midi performances contain many tempo changes.)

I have set my timebase to Beats (position, length, rate), but it also doesn't work with other timebases.

It seems that Reaper calculates the event offset time for the current midi item NOT based on the tempo changes since the midi item start time (integrating over tempo changes) but just based on the current tempo so it arrives at the wrong offset.

(Btw, the equivalent use case (midi CC linked to control BPM while recording midi) works in Ableton Live.)

Will this be fixed? I would really appreciate if this could be fixed
Is there any workaround for this right now?
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Old 06-14-2017, 12:45 PM   #2
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You should probably slave Reaper to MTC rather than change tempo via MIDI CC. Ableton Live doesn't do anticipative processing which might be a factor here. You could also try disabling the media buffer, but this WILL increase the CPU load considerably. However I'm not sure it would "fix" the issue.
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Old 06-15-2017, 07:23 AM   #3
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But with MTC it only gets the time in hours, minutes, seconds, frames.
How can I set the actual BPM? So that all my host-tempo synced effects work correctly?
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