[sdiy] Raspberry Pi 2 Synthesizer Project

[Gorka Garcia]

I implemented a 6 voice virtual analog synth + smaple playback drums using
the older raspberry pi 1. It was all in C, did not bother about going into
assembler. I was logging my progress here: http://juno6pm.blogspot.com
Have not had much time to work on it the last year, so it remains
unfinished. The filter still needs some work.
I would really like to replace the raspy 1 with a new one for the extra
processing power...

2016-02-07 14:49 GMT+01:00 Scott Gravenhorst <music.maker at gte.net>:

> Richie Burnett <rburnett at richieburnett.co.uk> wrote:
> >Sounds good. What did you write the code in? Assembly, C, python?
>
> The code is written entirely in C.  It's pretty much raw unoptimized code,
> so performance could increase with more attention to that.  Once I learn
> ARM assembly language (a bit more complex than PIC/dsPIC) I may include
> some of that for tightness.  The synth currently has no GUI, so it can run
> headless if needed.  I'm thinking about adding another different synth to
> make it bi-timbral, and eventually I'll add effects.
>
> -- ScottG
>
>
> >---- Scott Gravenhorst wrote ----
> >
> >>If you're on music-dsp, you already know about this.
> >>
> >>I purchased a Raspberry Pi 2 a bit before Christmas and have been
> >>working on a synthesizer.  Quad core ARMv7 900 MHz CPU.  I also have
> >>the Cirrus Logic/Element14 sound card (24 bit stereo up to 192 kHz.
> >>Line-in, line-out, S/PDIF and other features).
> >>
> >>So far, using ALSA, I've made an organ type polysynth (32 voices).
> >>Each voice is computed arithmetically as y=sin(a)+sin(2a).  I've
> >>isolated 2 of the 4 cores so that the synth runs in one core and the
> >>MIDI controller runs in another though the MIDI controller seems to >>run
> fine along side other linux stuff in a shared core.  It's >>currently
> working while LXDE deskstop runs.  The synth core uses >>about 55% CPU at
> idle and around 80% when using most of the voices. >>No crashes or
> glitches.  I will need to measure latency, but the >>latency contributed by
> ALSA buffering is down around 1/6 millisecond >>(period is 8 frames and the
> sample rate is 44100 Hz).
> >>
> >>I'm quite impressed by the power of this little thing, especially for
> >>a $35 computer board.
> >>
> >>-- ScottG
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