[stella] Tune2600 v0.5

[Thomas Jentzsch <tjentzsch@xxxxxx>]

Hi,
during the last days, I spent a lot of time in front of
my computer to get something different into my mind.

This is one of the results, I call it Tune2600.
The program wants to help Atari 2600 developers to find
good sounding distortion and pitch values for musical
tunes.

The program's algorithm doesn't care, if a note has the
exact frequency. It only tries, that the differences
between the notes are as correct as possible. So i.e. A4
must not be exactly 440Hz, if it is 20% of and all other 
notes are too, this is ok, because a normal ear (like
mine :) won't notice that.

This algorithm might not be perfect, but at least it
gives a good start. If you have any suggestions for
improvement, please tell me.

Usage:
It's a DOS program, but should run fine under Win9x. To
use it just enter (i.e.): 

Tune2600 /nc4d4e4g#4  (the notes must be ordered!)

As a result you'll get a list, and in the last columns
you'll see the distortion and pitch values. The program
only uses the distortions 4, 6, 12 and 14, which give
pure tones.
At the last row you'll see an error value for the whole
result. This is the weighted average error of frequency
differences. The whole algorithm is based on that error
value and tries to minimize it. So tunes with higher
error values should (but must not) sound worse than
those with lower values.

There are some additional parameters, which allow you
to influence the result. Use /? as parameter, and
you'll get a short help.

The /n parameters defines the notes. The format is
{Note[#]Octave} or i.e. c4d4f#4e5. You may enter up to
32 notes (but I doubt very much, that you'll find a
good sounding result then :). Without this parameter
the default notes are taken from the "Ring of Fire"
tune of Manuel's Sound Machine.

An important parameter is /f, which defines, how much
the frequency of the result may vary from the input
notes. A value of 100 equals one octave.

With /d you can change the maximum variation of the
difference between two notes. The normal difference
between two half notes is 2^(1/12)-1 (~6%). You
shouldn't use to high values here (<10), or the result
might not sound good.

The parameter /s activates an additional step, which
sometimes might improve the results. But this is very
slow, especially if you enter a lot of notes.

I hope you like it.

Thomas
_______________________________________________________
Thomas Jentzsch         | *** Every bit is sacred ! ***
tjentzsch at web dot de |

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