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Add audio input to the CPAL standalone backend

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This commit is contained in:
Robbert van der Helm 2022-08-21 17:55:09 +02:00
parent c46a044cb4
commit 1bee7f5333
3 changed files with 113 additions and 13 deletions
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10
Cargo.lock generated
View file

@ -2602,6 +2602,7 @@ dependencies = [
"nih_plug_derive",
"parking_lot 0.12.1",
"raw-window-handle",
"rtrb",
"serde",
"serde_json",
"simplelog",
@ -3544,6 +3545,15 @@ dependencies = [
"xmlparser",
]
[[package]]
name = "rtrb"
version = "0.2.2"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "9026ee10cf6d8388598dc10601819be903d14528e05ec3ab97b9ade70e24819c"
dependencies = [
"cache-padded",
]
[[package]]
name = "rustc-demangle"
version = "0.1.21"

3
Cargo.toml
View file

@ -49,7 +49,7 @@ assert_process_allocs = ["dep:assert_no_alloc"]
# Enables an export target for standalone binaries through the
# `nih_export_standalone()` function. Disabled by default as this requires
# building additional dependencies for audio and MIDI handling.
standalone = ["dep:baseview", "dep:clap", "dep:cpal", "dep:jack"]
standalone = ["dep:baseview", "dep:clap", "dep:cpal", "dep:jack", "dep:rtrb"]
# Enables the `nih_export_vst3!()` macro. Enabled by default. This feature
# exists mostly for GPL-compliance reasons, since even if you don't use the VST3
# wrapper you might otherwise still include a couple (unused) symbols from the
@ -100,6 +100,7 @@ clap = { version = "3.2", features = ["derive"], optional = true }
cpal = { version = "0.13.5", optional = true }
# The current upstream jack panics when it can't load the JACK library, which breaks the backend fallback
jack = { git = "https://github.com/robbert-vdh/rust-jack.git", branch = "feature/handle-library-failure", optional = true }
rtrb = { version = "0.2.2", optional = true }
# Used for the `vst3` feature
vst3-sys = { git = "https://github.com/robbert-vdh/vst3-sys.git", branch = "fix/note-off-event", optional = true }

113
src/wrapper/standalone/backend/cpal.rs
View file

@ -1,6 +1,10 @@
use anyhow::{Context, Result};
use cpal::{traits::*, Device, OutputCallbackInfo, Sample, SampleFormat, StreamConfig};
use cpal::{
traits::*, Device, InputCallbackInfo, OutputCallbackInfo, Sample, SampleFormat, Stream,
StreamConfig,
};
use crossbeam::sync::{Parker, Unparker};
use rtrb::RingBuffer;
use super::super::config::WrapperConfig;
use super::Backend;
@ -31,16 +35,60 @@ impl Backend for Cpal {
) {
// The CPAL audio devices may not accept floating point samples, so all of the actual audio
// handling and buffer management handles in the `build_*_data_callback()` functions defined
// below
// below.
// CPAL does not support duplex streams, so audio input (when enabled, inputs aren't
// connected by default) waits a read a period of data before starting the output stream
let mut _input_stream: Option<Stream> = None;
let mut input_rb_consumer: Option<rtrb::Consumer<f32>> = None;
if let Some((input_device, input_config, input_sample_format)) = &self.input {
// Data is sent to the output data callback using a wait-free ring buffer
let (rb_producer, rb_consumer) = RingBuffer::new(
self.output_config.channels as usize * self.config.period_size as usize,
);
input_rb_consumer = Some(rb_consumer);
let input_parker = Parker::new();
let input_unparker = input_parker.unparker().clone();
let error_cb = {
let input_unparker = input_unparker.clone();
move |err| {
nih_error!("Error during capture: {err:#}");
input_unparker.clone().unpark();
}
};
let stream = match input_sample_format {
SampleFormat::I16 => input_device.build_input_stream(
input_config,
self.build_input_data_callback::<i16>(input_unparker, rb_producer),
error_cb,
),
SampleFormat::U16 => input_device.build_input_stream(
input_config,
self.build_input_data_callback::<u16>(input_unparker, rb_producer),
error_cb,
),
SampleFormat::F32 => input_device.build_input_stream(
input_config,
self.build_input_data_callback::<f32>(input_unparker, rb_producer),
error_cb,
),
}
.expect("Fatal error creating the capture stream");
stream
.play()
.expect("Fatal error trying to start the capture stream");
_input_stream = Some(stream);
// Playback is delayed one period if we're capturing audio so it has something to process
input_parker.park()
}
// This thread needs to be blocked until audio processing ends as CPAL processes the streams
// on another thread instead of blocking
// TODO: Move this to the output stream handling
// TODO: Input stream
// TODO: Block the main thread until this breaky thing
let parker = Parker::new();
let unparker = parker.unparker().clone();
let error_cb = {
let unparker = unparker.clone();
move |err| {
@ -52,17 +100,17 @@ impl Backend for Cpal {
let output_stream = match self.output_sample_format {
SampleFormat::I16 => self.output_device.build_output_stream(
&self.output_config,
self.build_output_data_callback::<i16>(unparker, cb),
self.build_output_data_callback::<i16>(unparker, input_rb_consumer, cb),
error_cb,
),
SampleFormat::U16 => self.output_device.build_output_stream(
&self.output_config,
self.build_output_data_callback::<u16>(unparker, cb),
self.build_output_data_callback::<u16>(unparker, input_rb_consumer, cb),
error_cb,
),
SampleFormat::F32 => self.output_device.build_output_stream(
&self.output_config,
self.build_output_data_callback::<f32>(unparker, cb),
self.build_output_data_callback::<f32>(unparker, input_rb_consumer, cb),
error_cb,
),
}
@ -226,9 +274,30 @@ impl Cpal {
})
}
fn build_input_data_callback<T: Sample>(
&self,
input_unparker: Unparker,
mut input_rb_producer: rtrb::Producer<f32>,
) -> impl FnMut(&[T], &InputCallbackInfo) + Send + 'static {
// This callback needs to copy input samples to a ring buffer that can be read from in the
// output data callback
move |data, _info| {
for sample in data {
// If for whatever reason the input callback is fired twice before an output
// callback, then just spin on this until the push succeeds
while input_rb_producer.push(sample.to_f32()).is_err() {}
}
// The run function is blocked until a single period has been processed here. After this
// point output playback can start.
input_unparker.unpark();
}
}
fn build_output_data_callback<T: Sample>(
&self,
unparker: Unparker,
mut input_rb_consumer: Option<rtrb::Consumer<f32>>,
mut cb: impl FnMut(&mut Buffer, Transport, &[NoteEvent], &mut Vec<NoteEvent>) -> bool
+ 'static
+ Send,
@ -252,7 +321,7 @@ impl Cpal {
}
// TODO: MIDI input and output
let mut midi_input_events = Vec::with_capacity(1024);
let midi_input_events = Vec::with_capacity(1024);
let mut midi_output_events = Vec::with_capacity(1024);
// Can't borrow from `self` in the callback
@ -280,8 +349,28 @@ impl Cpal {
transport.time_sig_denominator = Some(config.timesig_denom as i32);
transport.playing = true;
for channel in buffer.as_slice() {
channel.fill(0.0);
// If an input was configured, then the output buffer is filled with (interleaved) input
// samples. Otherwise it gets filled with silence.
match &mut input_rb_consumer {
Some(input_rb_consumer) => {
for channels in buffer.iter_samples() {
for sample in channels {
loop {
// Keep spinning on this if the output callback somehow outpaces the
// input callback
if let Ok(input_sample) = input_rb_consumer.pop() {
*sample = input_sample;
break;
}
}
}
}
}
None => {
for channel in buffer.as_slice() {
channel.fill(0.0);
}
}
}
midi_output_events.clear();