shithub: neindaw

ref: b1e84a59c5c100e9aa5c31eb39d58e174289249d
dir: /README.md/

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# faust9p

Tools to compile [Faust](https://faust.grame.fr) DSP code to a 9p
server running on Plan 9.

## Testing

Since Faust isn't(?) ported to Plan 9 (yet?), first you need to
generate some code on some other OS that supports it, by running
`./gen.sh`.

So far only one instrument provided, which is a kick drum.

```
% ./6.out -m /n/kick
% cd /n/kick

# allocate one instance
% cd `{cat clone}

# check the A oscillator frequency
# the order is: type value initial min max step
# it's different for different UI elements
% cat K*/a/frequency/ctl
vslider	100.000000	100.000000	10.000000	200.000000	5.000000

# raise frequency to 160Hz
% echo 160 > K*/a/f*/ctl

# toggle the gate, we need to compute once in between for it to actually be processed
# then listen to the sound
% echo 0 > 'Kick Drum/control/gate/ctl' && \
	dd -if data -of /dev/null -count 1 -quiet 1 && \
	echo 1 > 'Kick Drum/control/gate/ctl' && \
	audio/pcmconv -i f32c2r44100 -l 128000 < data > /dev/audio

# increase the delay of A oscillator
% echo 0.2 > 'Kick Drum/a/delay/ctl'

# now you can repeat the listen command to hear the difference
```

## Description

A DSP fs presents an interface to create instances of a DSP class by
reading the `clone` file.  In the resulting directory `metadata` is
used to read general info about the dsp, `data` is used to supply
input to the DSP (if it has any inputs) by writing to it, and output
can be read from it.  The format is raw stream of `float`.

Each DSP instance, in addition to the mentioned files, provides a file
tree that reflects the UI elements.  UI elements provide `ctl` file to
read initial and current, maximum and minimum, step, and may be used
to write a new value to it.  `metadata` is provided to read/write
UI-specific metadata key/values.

Several DSPs may be connected by chaining their `data` interfaces
together.  If some parameters need to be changed dynamically during
processing with frame accuracy, it can be achieved by running the
chain for a chunk of data, changing the parameters, then continuing
processing.

## TODO

 * a program to control DSP through an actual UI in rio
 * `<ui>/value` to watch the changes, add frame offset as well to know
   when it actually changed
 * optional frame offsets for all commands, perhaps that's easier than
   running and stopping the processing all the time
 * `reset` command for groups
 * forbid writing values that are out of min/max range: return an error
 * add writable `metadata` for each instance
 * allow adding new key/values to `metadata`
 * add some way to read and write the whole configuration of an instance
   in an easy way, so instances can be cloned, or configs saved to disk
   as presets