I compared your MIDI files and the original's tempo is 56 BPM while the fixed one is 55 BPM for some reason. This explains the different time lengths.

Thanks!...you're right. Original MIDI was recorded with 56 BPM setting in Pianoteq, and that value must be preserved because is used as timebase.

May be help other users, in the following video, shows how to change MIDI tempo with MidiEditor:

https://youtu.be/_yYM8kKpjsI

I've recorded this MIDI file using Pianoteq:

MIDI FILE LINK 1

Time duration: 4:08.9

Then I've edited that file using MidiEditor software.

Just change the property velocity of one note, from 23 to 62. Note duration is the same.

This is the new MIDI file modified:

MIDI FILE LINK 2

Now, I want to play this file in Pianoteq and total time duration has changed to 4:13.4 (according to Pianoteq).

This is bad becouse I can't syncrhonize this new duration with a previously recorded video.

My question is, how can I edit MIDI files and preserve time duration?.

Thanks!

PS: I've tried REAPER software with similar results.