[LAU] Sound Chip as a synthesizer on Linux. Thoughts, ideas?

Ralf Mardorf ralf.mardorf at rocketmail.com
Fri Jul 11 03:31:29 UTC 2014


On Thu, 2014-07-10 at 22:43 -0400, Tim E. Real wrote:
> zynaddsubfx

Calf monosynth, phasex and a few other synth are likely closer to the
OP's needs. Has somebody already tested Bristol's SID emulation?
http://bristol.sourceforge.net/sidney.shtml

OT:
> Probably because there was no way to produce sample driven audio from SID.
> Actually,  that's not entirely true:
> 
> Later in this thread I think Len refers to the General Instrument AY-3-8910.
> 
> Ironically both the Commodore SID and the AY-3-8910 *can* produce 
>  sampled audio, the SID in two different ways:
> 
> 1) Use the SID's 12-bit Pulse Width Modulators to produce PWM audio.
> Drawback: Maximum operating frequency is around 3Khz, which gets into 
>  the audio, so you need a low-pass filter down there.
> 
> 2) Use the SID's or the AY-3-8910's Volume registers to produce sampled audio.
> (Set the SID oscillators for 'DC' - the highest f number, or the GI's volume 
>  mode to a 'DC' envelope.)
> Drawback - it's only 4-bit audio samples.

I used 2-bits, but even 8-bit was possible,
http://www.c64-wiki.de/index.php/Audiodigitizer and I guess I used the
same digitiser as shown in this link, sure, I used a sane PCB and not
such an ugly one.

The drawback, while the C64 was able to do MIDI hard real-time, better
than Linux is able to do, it was very slow and the hard real-time
processing of MIDI events could become problematic when you tried to
provide running status. The MIDI sound sampler I wrote didn't come with
running status, so I had to disable it for the Atari ST sequencer output
that sent the MIDI events to the C64 sound sampler. AFAIK MIDI running
status can't be disabled for Linux MIDI out.



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