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MIDI-PAC - Firmware 0.6

by RobertVroemisse on 19-01-2012, 10:28
Topic: Development
Tags: Firmware, Worp3, MIDI-PAC
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Dutch MSX user WORP3 (Tjeerd Veenstra) is still busy optimizing the firmware of his MIDI-PAC cartridge. This hardware extension allows you to connect a MIDI synthesizer to an MSX and play music intended for MSX-MUSIC (simultaneously, if desired) on the synth. New in this firmware (version 0.60 already) is an experimental anti-modulation that is nothing less than a complicated algorythm that -realtime- separates the base-frequency (the actual note) from additional frequencies (modulation, vibrato and/or pitch) and converts these frequencies into MIDI-data. The results of this new method of handling frequencies can be heard right here.

Relevant link: Firmware 0.60

Comments (4)

By Sander

Ambassador (1625)

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19-01-2012, 13:24

Nice gift! Great for Nijmegen, thanks Tjeerd!

By Google

By WORP3

Champion (357)

WORP3's picture

19-01-2012, 15:35

I will give you a demonstration @Nijmegen so you can hear the difference between de both versions. Got myself a small speaker set so you won't have to put on a headphone Wink

By wolf_

Ambassador (9123)

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19-01-2012, 16:01

WORP3: am I right in thinking that you split up the (MSX) chp's tone frequency into a MIDI note and a pitchbend value (e.g. 456Hz split up into A-3 and a 'fine tune' of 16)? If yes: if this pitchbend range is max -24/+24, would that imply that you can't correctly manage C-8 pitching all the way down to C-1?

By WORP3

Champion (357)

WORP3's picture

19-01-2012, 19:59

@wolf: i'm not splitting up the pitchbendings from the base tone as it's almost impossible to distinguage from modulation or linked notes. That is because it's all done in realtime and you can't predict the future. It was a lot easier if i could just buffer the stream for a while, but that would take up to much memory and will give some nasty dealy in the music (compared to the msx audio output).
I'm only filtering out the frequency modulations (and give the synth a seperate modulation command) and handle both the linked notes and pitch bendings both as linked notes. This way you wont get a real pitch bending, but a contiguous sequence of notes which in most cases is giving the same effect as a real pitch bending Smile2
Even if it was possible to filter out the pitch bendings, it would be a real pain in the but, to overcome all the different synth modules and there specific way of handling bendings and their ranges.
But you are right that in most cases the pitch range won't be enough to handle large bendings in the first place.

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