ref: 84b8c6bb8409ba6d693f0080af2e2eaccfa3a718
dir: /README.md/
# 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 100 100 10 200 5
# 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