On 13/12/2010 08:23, Stefan Thomas wrote:
> Dear community,
> I have a problem with using samples.
> Because I want to create "realistic" Instruments, I've sucessfully
> related different sounds to different midi-keys.
> But, as everybody knows, different registers sound sometimes totally
> different and it is hard to make a smooth transition between them.
> How can I achieve this aim?

With wind instruments at least, the registers ~are~ different; so the 
short answer is "lots of practice". All the notes in the upper registers 
are harmonics of the lowest register. And on the oboe, adjacent notes 
even within a register can be very different. So a "smooth transition" 
is a strictly relative concept, enabled by skill but limited by 
acoustics and materials. And all rather obvious in the case of violins 
etc, with multiple strings to contend with.

So, "realistic" and "smooth transition" may be somewhat conflicting goals!


Richard Dobson



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On 13/12/2010 11:36, Stefan Thomas wrote:
> Dear Richard,
> Ok, I've understood that I've choosen a difficult task.
> But could You give me maybee a little hint?
> Can I try to do it with filters?
>

~Possibly~.

It is basically an exercise in morphing. Say you want to generate the 
scale from A up to E on the flute (across the "break" between C# and D). 
"first-finger" C comes out of a large tone hole high up (low ratio  of 
sounding length to diameter), E comes out of a much longer sounding 
length, as a second harmonic. C# (the one "l'Apres-Midi" starts with) 
comes out of a very small tone hole, much higher up than it should be so 
it can double up as an "octave key" (Blame Boehm for that!) so sounds 
~very~ different to each.

So, for example, you might use pvcross or similar to find an 
intermediate  timbre between A and E (pitch shifted to the same note of 
course, and the midpoint of pvcross adjusted according to the pith of 
the target note), and pitch shift the results to get the intermediate 
notes. Maybe with a bit of formant preservation thrown in for good 
measure. It depends of course on how widely spaced your samples are, 
pitch-wise.

What the player does is to adjust the tone of each note, very slightly, 
to achieve as smooth-sounding a scale as possible - toning down notes 
that are naturally rich, and working extra hard on ones that are not. In 
the case of all the flute samples I have heard this is ~not~ done very 
well. Think of the image of the waiter carrying a tray of drinks, on a 
rolling ship. That is pretty much what it feels like, most of the time.

As it was taught to me decades ago: "here is the bottom note of the 
piano... here is the top note. They sound very different. But here is 
the chromatic scale from one to the other ... there is no single point 
where you hear the tone colour change". Which suggests that the sound 
designer will have to work just as hard to get the same effect. The fact 
that it involves a lot of work rather explains why sample libraries 
either have a separate sample for each note (and they cost 
commensurately more), or have abrupt and arbitrary transitions.

As for that pesky C# - flutes were and often are made with an extra 
full-size C# tonehole so players could get a matched tone on it easily; 
so there are precedents of a sort for this sort of tonal tinkering!

(All those punters who claimed that sample libraries would make live 
musicians redundant, really didn't have a clue. Ears like old boots, the 
lot of them.)


Richard Dobson






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