----- Original Message -----
From: Heikki Johannes Junes
To: Nick Bailey
Cc: [email protected]
Sent: Thursday, June 14, 2007 10:06 PM
Subject: Re: [Rosegarden-devel] Transposition strategies
2007/6/14, Nick Bailey <[EMAIL PROTECTED]>:
On Sunday 10 June 2007 15:55:45 D. Michael McIntyre wrote:
> On Saturday 09 June 2007, you wrote:
> > So the piece should sound the same, simply look different?
>
> Right. More broadly, we really need an easy way to flip around between
> written transpositions....
> That looks like just the sort of "you break it, you bought it" thing I was
> talking about. :) This stuff is really tricky to get right. It seems so
> simple on the surface, but it's so easy to miss the edge cases, and so
hard
> to get them working without breaking something in the middle.
Hear, hear!
And the reason it's hard to get right is also wrapped up in the coding ideal
of Rosegarden: that it shouldn't get in the way of doing MIDI I/O easily.
We
were (I hope) very careful to follow this lead, which is a good one, with
our
microtonal and pitch-tracker patches. But when it comes down to it, MIDI is
a
highly inadequate representation of musical information (as already noted,
it
can't even distinguish enharmonic equivalents, for example!)
MIDI should be an approximation of the notation. (notation->midi) If changes
are done in
notation side, the effects are predictable. (midi->notation?) But if changes
are made in MIDI
side, the changes in notation side may depend from case to an another,
because information is lost in the approximation.
There are several other way of storing pitch, such as Base-40 or Binomial
representations (pitch class/spelling), but we think the only real way to do
it is to use a circle-of-fifths representation. We're working on one which
should handle almost everything including 19-ET etc microtonality. It's only
assumption is that all music is diatonic. And it makes transposition really
easy.
Also, it is only assumption that music fits to any quantization of pitches.
Think of
a glissando which is played with violin or trombone.
But then you'd have to be explicit about how you get from the note's pitch
to
its frequency. MIDI completely ignores this step. Musicians call
it "temperament", and the results of just shoe-horn-ing everything into
12-ET
are shocking (there's a good little applet to show you just how out of tune
we all are here:
http://www.j2b.co.uk/tuning
:) ) Only keyboard players use anything like ET. Everyone else bends
everything. There's the MIDI tuning standard, but not very many
applications
support that.
Even pianos are often not exactly tuned into equal temperement (ET), but the
higher notes may be tuned sligtly over. The reason may lie in physics: When you
hit a note which is very low, the string in piano becomes longer and more
stressed, which increases its tuning. After few vibrations, the tuning of the
string in piano becomes lower as the amplitude of oscillation decreases.
EMJ: Being a piano tuner, the reason I think you are referring to here is
inharmonicity. See this article: http://en.wikipedia.org/wiki/Stretched_tuning
Of course, these effect should not appear in notation.
But do you want all this stuff in a sequencer? I doubt it, at least not as
a
high priority. The pitchtracker supports temperament through the use of
tuning files. It depends where you chose to draw the line, I guess.
Nick/.
http://www.n-ism.org
IMHO, handling microtonalism is a difficult problem, especially, if you think
that a single tone
consist of the base tone and its second, third, etc. harmonics. Does some
other base approximate more efficiently the 2nd, 3rd, 4th, and 5th harmonic
tones of a base tone, than 12-ET does?
EMJ: The basic consideration for a temperament is to get the intervals of the
scale tones' fundamentals as well-sounding as possible.
It is easier to consider only the base tone, to fix notes into 12-ET and to
give each note an adjustment in tuning, if it deviates from 12-ET.
Of course, the music notation commonly used is just 12-ET approximation of
the performed music.
EMJ: Our traditional western music notation is older than the equal
temperament (at least the latters wide-spread use) so I don't think the
notation system is linked to the 12-tone equal temperament in such a way. But
it can serve as an approximation, that's true.
Regards,
Magnus-------------------------------------------------------------------------
This SF.net email is sponsored by DB2 Express
Download DB2 Express C - the FREE version of DB2 express and take
control of your XML. No limits. Just data. Click to get it now.
http://sourceforge.net/powerbar/db2/
_______________________________________________
Rosegarden-devel mailing list
[email protected] - use the link below to unsubscribe
https://lists.sourceforge.net/lists/listinfo/rosegarden-devel
