[A6] Re: NRPN Again

[Protokol]

> ... i actually wanted to reverse the sweep so it starts from open and ends
> in the closed position. Rather then have to setup another track and go
> through the entire process again, I tried to just draw it in as it would
> have been easier.
>

There's a lot of sequencers that can also reverse MIDI events as a process,
rather than actually going in and editing.

NRPN editing is pretty nightmarish if the editor cannot translate between
the format of MIDI, and the resolution needed.

Although Robert gave a good rundown, I'm going to just revisit the topic to
reinforce it:

I might be giving redundant information, but it's interesting stuff that
maybe someone will find useful.  With 7 bits, you get 128 steps of
resolution (2 to the power of 7).  But, NRPNs increase resolution by
stacking bits, so instead of 7 you can get 14 bits.  With 14 bits, you get
16,384 steps of resolution.  Unfortunately, MIDI was built with the
short-sightedness of using 7 bits, so those 16,384 steps need to be split
into 128 discrete steps that in themselves hold 128 steps.  Almost like if
you had a ruler with 128 meters, and then drew 128 lines between each meter
mark or line.  The Most Significant Bits (MSBs) would represent the meter
marks in this example, and the Least Significant Bits (LSBs) would represent
the 128 lines between the meter marks.  It is common practice, as Robert
mentioned, to use 2 MIDI bytes (using only 7 of the bits for data) for
Pitchwheel.  The resolution is still 16384, but pitch goes up AND down,
which leaves only 8192 steps for the UP and DOWN, which is 16384 divided by
2.  Although the PitchWheel parameter is an RPN (Registered Parameter
Number), because it is a common MIDI parameter that can be used among many
MIDI instruments.  While an NRPN (Non-Registered Parameter Number) is not
common and usually specific to that particular instrument.

As you can probably see the system could allow further stacking of bits to
achieve even higher resolution.  This is important, because I think the
Andromeda uses 3 Midi Bytes for a non-standard NRPN.  I'm not exactly sure,
but the last time I recorded event information there were more than 2
Controller messages being sent (and I cannot imagine Alesis using more than
21 bits of resolution).  Having 3 Midi Bytes would be 128 steps * 128 steps
* 128 steps = 2,097,152 steps... Wow!  Almost like you grabbed that Meter
stick once again and drew 128 microscopic lines between all the original 128
lines you drew between all the 128 meter lines.  Which, by the way, would
probably take you over a month and a half if you drew them at a rate of a
line every 2 seconds with no rest or sleep.  Maybe drawing lines is not such
a good idea come to think of it ;0)

-proto-