Reverse engineering?

Manuel, and anyone else:

Is there a way to reverse engineer a file that has been "Scala'd"? For instance, Margo posted a 14tet midi file that I thought would be fun to use, but naturally it is transformed into multiple tracks (channels) with pitch bends. What I'd like to do is return it to a single track of midi data that could be used with a synth tuned to 14tet.

Not urgent.

Cheers,
Jon

--- In MakeMicroMusic@yahoogroups.com, "Jonathan M. Szanto"
<JSZANTO@A...> wrote:
> Manuel, and anyone else:
>
> Is there a way to reverse engineer a file that has been "Scala'd"? For
> instance, Margo posted a 14tet midi file that I thought would be fun to
> use, but naturally it is transformed into multiple tracks (channels)
with
> pitch bends. What I'd like to do is return it to a single track of midi
> data that could be used with a synth tuned to 14tet.

I'm totally confused--it sounds as if you are asking how to convert a
midi file into a midi file. What is it you actually want as the end
result?

Gene Ward Smith wrote:

>--- In MakeMicroMusic@yahoogroups.com, "Jonathan M. Szanto"
><JSZANTO@A...> wrote:
> >
>>Manuel, and anyone else:
>>
>>Is there a way to reverse engineer a file that has been "Scala'd"? For >>instance, Margo posted a 14tet midi file that I thought would be fun to >>use, but naturally it is transformed into multiple tracks (channels)
>> >>
>with > >
>>pitch bends. What I'd like to do is return it to a single track of midi >>data that could be used with a synth tuned to 14tet.
>> >>
>
>I'm totally confused--it sounds as if you are asking how to convert a
>midi file into a midi file. What is it you actually want as the end
>result?
> >

He wants to know how to strip out the pitch bends.

--
* David Beardsley
* microtonal guitar
* http://biink.com/db

db/Gene,

{you wrote...}
>He wants to know how to strip out the pitch bends.

Actually, what I'm wondering is if I

- strip the bends (easy enough to do)
- collapse the multiple channels into one channel
- play the resulting single-midi track on a 14tet-tuned synth

will I get the same result? Of course, I should just try it and see. Maybe later tonight...

Cheers,
Jon

Jonathan M. Szanto wrote:

>db/Gene,
>
>{you wrote...}
> >
>>He wants to know how to strip out the pitch bends.
>> >>
>
>Actually, what I'm wondering is if I
>
>- strip the bends (easy enough to do)
>- collapse the multiple channels into one channel
>- play the resulting single-midi track on a 14tet-tuned synth
>
>will I get the same result? Of course, I should just try it and see. Maybe >later tonight...
>
I don't think so. I think you would have to remap the notes for your synth?

--
* David Beardsley
* microtonal guitar
* http://biink.com/db

db,

{you wrote...}
>I don't think so. I think you would have to remap the notes for your synth?

That is exactly what I was thinking might happen. I'll muck around with it.

Cheers,
Jon

--- In MakeMicroMusic@yahoogroups.com, "Jonathan M. Szanto" <JSZANTO@A...> =

wrote:
> db/Gene,
>
> {you wrote...}
> >He wants to know how to strip out the pitch bends.
>
> Actually, what I'm wondering is if I
>
> - strip the bends (easy enough to do)
> - collapse the multiple channels into one channel
> - play the resulting single-midi track on a 14tet-tuned synth
>
> will I get the same result?

With 14tet, certain pairs of notes would end up the same note in 12tet. So=
what a
program would actually have to do would be:

1. Make a list of all the pitch bend amounts used.

2. Figure out which MIDI note numbers fall during which pitch bends.

3. Put these together into a scale - perhaps a scala .scl.

4. Here you could specify a keyboard mapping or just use a default - move a=
ll of the
MIDI notes to the corresponding position in the mapping and make a MIDI (or=

whatever) out of this.

Wow, that actually seems like something I have the skills to program in the=
forseeable
future! The only confusing aspect would be how to treat continuous pitch b=
ends
(ones that move during a note's sounding). 'Twould be a useful thing to ha=
ve,
although the composer can often provide "unretuned versions" (as Mats Öljar=
e does)
to bypass the need.

> He wants to know how to strip out the pitch bends.

Not exactly... It would take more than *that* to turn it into a file
playable by an instrument already tuned to 14-tet tuning.

> Actually, what I'm wondering is if I
> - strip the bends (easy enough to do)
> - collapse the multiple channels into one channel
> - play the resulting single-midi track on a 14tet-tuned synth
> will I get the same result? Of course, I should just try it and see.
> Maybe later tonight...

That won't work. Think about it a bit... Here's what you would have to do:

Make a tuning table T of 128 note frequencies in 14-tet. For each note in
the MIDI file you are converting, calculate the frequency of the note by
adding the pitchbend offset to/from the associated MIDI note number. And
for that MIDI note number, substitute the MIDI note number in the 14-tet
tuning table T with the frequency closed to the one you found.

This will involve *changing* MIDI note numbers, not just "stripping pitch bends".

Rick

--- In MakeMicroMusic@yahoogroups.com, Rick McGowan <rick@u...> wrote:

> This will involve *changing* MIDI note numbers, not just "stripping
pitch bends".

If I was going to do this sort of thing, I'd use Maple; probably not a
useful suggestion for most people.

Gene suggested...

> If I was going to do this sort of thing, I'd use Maple; probably
> not a useful suggestion for most people.

Ah, another thought just occurred to me... One could use Perl or some
other scripting language. There's a program that can convert MIDI files to
text files and back (It's by Piet van Oostrum, "MT2T/T2MF"). In text
format, it might not be real hard to parse the notes and pitch-bends, and
then re-write the file and re-convert to MIDI file.

Rick

Gene Ward Smith wrote:

> --- In MakeMicroMusic@yahoogroups.com, Rick McGowan <rick@u...> wrote:
>
> > This will involve *changing* MIDI note numbers, not just "stripping
> pitch bends".
>
> If I was going to do this sort of thing, I'd use Maple; probably not a
> useful suggestion for most people.
>
The problem here is that there are two major paths to doing microtonal midi. One path maintains the 12tet value for each midi pitch number and then retunes, note-by-note, via pitch bends, the other path ignores the 12tet values of each midi pitch number and instead maps each tone of the desired tuning to a midi-pitch number (with the precise tuning of that pitch number done through either an additional tuning specification table or a full-keyboard tuning of the synth or a rendering program or a relay program like InTun). Could Maple -- or a similar package -- be used to make a stand-alone program that would simply locate each occurance of a given pitch number + pitch bend instruction (as in the first path) and replace it with a pitch number (as in the second path), or vice versa?

Daniel Wolf