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Pitch shift problems

Posted: Mon Dec 26, 2011 10:56 pm
by Dorsetmike
I'm using pitch shift to complete some instrument sample sets which have 4 notes per octave, so I need to pitch shift plus and minus a semitone on each of the four notes per octave.

Sometimes pitch shift works correctly, the for no apparent reason it goes wrong, example trying to sift C# down to C it thinks I'm shifting from G# to G and if I click OK (as one is likely to do when one is doing such repetitive actions) I then wonder why when I do a quick listen run through the scale it suddenly drops 2 or 3 notes down when it should be going up in semitones.

It's not consistent either, sometimes does a couple of octaves no problem then screws up 2 or three notes.

Cheers MIKE

Re: Pitch shift problems

Posted: Mon Dec 26, 2011 11:20 pm
by Gale Andrews
Do you mean Effect > Change Pitch?

If so, that works only on a percentage change. C# to C is thus identical to G# to G.

See http://manual.audacityteam.org/man/Change_Pitch .


Gale

Re: Pitch shift problems

Posted: Tue Dec 27, 2011 4:01 pm
by Dorsetmike
Yes, Effects - Change Pitch is the problem; it seems to be OK around the middle registers - around middle C, however in the lower registers it's often way out. I've not managed to get into the higher registers yet, still trying to fight my way up!

The frequencies shown in the dialogue box bear no resemblance to what they should be, example midi note 036 C3, shows a frequency of 479.348Hz (between 070-A# and 071-B, assuming A=440Hz) should be 130.81Hz, as for even lower registers, trying to work between midi 021-A0 and 033-A1 is extremely hit and miss.

Cheers MIKE

Re: Pitch shift problems

Posted: Wed Dec 28, 2011 2:22 am
by Gale Andrews
Change Pitch does not detect pitch other than the first identifiable pitch it finds in the selection. It does not detect the tonality or "key" of a piece.

It does not change an arbitrary note to the pitch indicated in "Pitch: To:". It changes pitch of the whole selection by the percentage indicated in the "Percent Change" box, irrespective of the pitch(es) in the selection.

If you believe "C3 shows a frequency of 479.348Hz" please give exact steps to reproduce the issue, including how you produced C3 in the Audacity track.



Gale