actually add audio.rs

Co-authored-by: Eskil Queseth <eskilq@kth.se>

1 files changed, 54 insertions, 0 deletions

diff --git a/mumd/src/audio.rs b/mumd/src/audio.rs
new file mode 100644
index 0000000..d1a309c
--- /dev/null
+++ b/mumd/src/audio.rs
@@ -0,0 +1,54 @@
+use cpal::{Sample, SampleFormat, OutputCallbackInfo, Stream, StreamConfig, SampleRate};
+use cpal::traits::DeviceTrait;
+use cpal::traits::HostTrait;
+use std::collections::VecDeque;
+use std::sync::Arc;
+use std::sync::Mutex;
+
+pub struct Audio {
+    pub output_buffer: Arc<Mutex<VecDeque<f32>>>, //TODO ring buffer?
+    pub output_config: StreamConfig,
+    pub output_stream: Stream,
+}
+
+impl Audio  {
+    pub fn new() -> Self {
+        let output_buffer = Arc::new(Mutex::new(VecDeque::new()));
+
+        let host = cpal::default_host();
+        let device = host.default_output_device().expect("default output device not found");
+        let mut supported_configs_range = device.supported_output_configs()
+                                                .expect("error querying configs");
+        let supported_config = supported_configs_range.next()
+                                                    .expect("no supported config??")
+                                                    .with_sample_rate(SampleRate(48000));
+        let supported_sample_format = supported_config.sample_format();
+        let config: StreamConfig = supported_config.into();
+
+        let err_fn = |err| eprintln!("an error occurred on the output audio stream: {}", err);
+
+        let stream_audio_buf = Arc::clone(&output_buffer);
+        let stream = match supported_sample_format {
+            SampleFormat::F32 => device.build_output_stream(&config, curry_callback::<f32>(stream_audio_buf), err_fn),
+            SampleFormat::I16 => device.build_output_stream(&config, curry_callback::<i16>(stream_audio_buf), err_fn),
+            SampleFormat::U16 => device.build_output_stream(&config, curry_callback::<u16>(stream_audio_buf), err_fn),
+        }.unwrap();
+
+        Self {
+            output_buffer,
+            output_config: config,
+            output_stream: stream,
+        }
+    }
+}
+
+fn curry_callback<T: Sample>(buf: Arc<Mutex<VecDeque<f32>>>)
+                            -> impl FnMut(&mut [T],
+                                        &OutputCallbackInfo) + Send + 'static {
+    move |data: &mut [T], _info: &OutputCallbackInfo| {
+        let mut lock = buf.lock().unwrap();
+        for sample in data.iter_mut() {
+            *sample = Sample::from(&lock.pop_front().unwrap_or(0.0));
+        }
+    }
+}