Shifting pitch in a MIDI file?

[Ralf Mardorf]

On Mon, 2010-12-13 at 12:59 +0000, Angel de Vicente wrote:
> Hi all,
> 
> yesterday I was trying to find a way to shift the pitch in a MIDI file 
> but couldn't figure out a way to do it, so I'm looking for advice here...
> 
> My situation is as follows. I have a MIDI file of a piece (for four 
> guitars), and I just want to mute one of the tracks and play along with 
> my real guitar (a sort of virtual quartet...). But the problem is that 
> the tuning of my computer is wrong (I read somewhere that DELL laptops 
> had this problem. I'm not sure, but in any case the standard A at 440Hz 
> sounds actually like a C).
> 
> I could tune up my guitar, but that is quite inconvenient, specially if 
> later I want to play with more instruments, so I was hoping that I could 
> find a way to tune up or down the whole MIDI output. The Virtual 
> Keyboard has a pitch wheel, which it would be exactly what I'm looking 
> for if it could be applied to the whole MIDI output... In Rosegarden I 
> didn't find anything... In Qtractor I could load up plugins that seemed 
> promising (if I remember correctly I could find four plugins with names 
> like pitchshift, but I couldn't make them to work, plus they applied to 
> individual tracks, and not to the whole MIDI output).
> 
> Any pointers?
> 
> Thanks,
> Ángel de Vicente

Add a track and send Pitch to all channels, but note, that the steps for
the Pitch Wheel are defined by the synth e.g. 0 or 2 or 12 semi
steps ;). MIDI does also know a master tune, but this isn't supported by
every synth. You might have not an issue for the sample rates, regarding
to the bad tuning, I once had this too. I did a new install and the
tuning was ok.

Perhaps you can record the MIDI instruments to audio tracks and fix it
with rubberband or a pitch shift effect, if it's not to extremely out of
tune.

Hth,

Ralf