FS#2231 - Pitch adjustment in musical terms (for practicing musicians)

Attached to Project: Rockbox
Opened by Bruce Bertrand (brucebertrand) - Thursday, 17 June 2004, 04:41 GMT
Last edited by Rani Hod (RaeNye) - Wednesday, 20 September 2006, 23:07 GMT
Task Type Feature Requests
Category Music playback
Status Closed
Assigned To No-one
Operating System All players
Severity Low
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 0
Private No


For musicians who use the pitch adjustment feature for
practice (mostly with Jazz playalong's), adjusting the
pitch with the current method is not very useful.

A nice option would be to adjust the pitch by semitones
(or half steps).

To raise pitch in equally tempered half steps, use the
following equation:

F = (2^(1/(12/N))) * B

F = end frequency
B = starting frequency
N = # of half steps displaced (absolute value)

To lower pitch, divide, rather than multiply, by B

Is accurate enough math possible (and efficient) with
the archos (recorder)?

If not, you can use: F = B * 1.06^N

This method is only relatively accurate to about a
perfect 5th (7 half steps), which is OK. A perfect 5th
up plus a perfect 5th down gives you more than an
octave, and thus, covers all keys.

Also usefull, for those who would be thinking in
musical terms, is displaying the adjustment not by the
number of half steps (+4 , -2 , etc...) , but by
interval (M3 up, m2 down, etc...)

For reference, if whoever might implement this doesn't
have a musical background, a interval list follows:

1 = m2 (minor 2nd)
2 = M2 (Major 2nd)
3 = m3
4 = M3
5 = P4 (Perfect 4th)
6 = TT (Tritone)
7 = P5
8 = m6
9 = M6
10 = m7
11 = M7
12 = 8va (Octave)

Too bad there's not enough processing power to do this
without affecting the tempo.

This task depends upon

Closed by  Bj√∂rn Stenberg (zagor)
Friday, 10 November 2006, 19:07 GMT
Reason for closing:  Fixed
Additional comments about closing:  Closing all feature requests.
Comment by Barry Wardell (barrywardell) - Tuesday, 10 October 2006, 18:28 GMT
I have added  FS#6145  as a related task. It has a patch for this, but affects the tempo as well as the pitch.