no triply buffered audio

gb-emu/src/audio.rs

@@ -5,7 +5,7 @@ use cpal::{
 use futures::executor;
 use gb_emu_lib::connect::{AudioOutput, DownsampleType};
 
-const FRAMES_TO_BUFFER: usize = 1;
+const BUFFERS_PER_FRAME: usize = 100;
 const DOWNSAMPLE_TYPE: DownsampleType = DownsampleType::ZeroOrderHold;
 
 pub fn create_output(muted: bool) -> (AudioOutput, Stream) {
@@ -25,8 +25,7 @@ pub fn create_output(muted: bool) -> (AudioOutput, Stream) {
 
     let sample_rate = config.sample_rate().0;
 
-    let (output, mut rx) =
+    let (output, mut rx) = AudioOutput::new(sample_rate as f32, BUFFERS_PER_FRAME, DOWNSAMPLE_TYPE);
-        AudioOutput::new(sample_rate as f32, true, FRAMES_TO_BUFFER, DOWNSAMPLE_TYPE);
 
     let stream = if muted {
         device

gb-vst/src/lib.rs

@@ -67,8 +67,8 @@ pub struct GameboyEmu {
 type FrameReceiver = Mutex<Option<Receiver<Vec<[u8; 4]>>>>;
 type JoypadSender = Mutex<Option<Sender<(JoypadButtons, bool)>>>;
 
-const FRAMES_TO_BUFFER: usize = 1;
+const BUFFERS_PER_FRAME: usize = 1;
-const DOWNSAMPLE_TYPE: DownsampleType = DownsampleType::ZeroOrderHold;
+const DOWNSAMPLE_TYPE: DownsampleType = DownsampleType::Linear;
 
 const ROM: &[u8; 65536] = include_bytes!("../../test-roms/mGB.gb");
 
@@ -218,8 +218,7 @@ impl Plugin for GameboyEmu {
         if let Some(ref mut vars) = self.vars {
             let (output, rx) = AudioOutput::new(
                 buffer_config.sample_rate,
-                false,
+                BUFFERS_PER_FRAME,
-                FRAMES_TO_BUFFER,
                 DOWNSAMPLE_TYPE,
             );
 
@@ -232,8 +231,7 @@ impl Plugin for GameboyEmu {
 
             let (output, rx) = AudioOutput::new(
                 buffer_config.sample_rate,
-                false,
+                BUFFERS_PER_FRAME,
-                FRAMES_TO_BUFFER,
                 DOWNSAMPLE_TYPE,
             );
 

lib/src/connect/mod.rs

@@ -42,18 +42,16 @@ pub trait Renderer<Format: From<Colour>> {
 pub struct AudioOutput {
     pub sample_rate: f32,
     pub send_rb: AsyncHeapProducer<[f32; 2]>,
-    pub wait_for_output: bool,
     pub downsample_type: DownsampleType,
 }
 
 impl AudioOutput {
     pub fn new(
         sample_rate: f32,
-        wait_for_output: bool,
+        buffers_per_frame: usize,
-        frames_to_buffer: usize,
         downsample_type: DownsampleType,
     ) -> (Self, AsyncHeapConsumer<[f32; 2]>) {
-        let rb_len = (sample_rate as usize / 60) * frames_to_buffer;
+        let rb_len = (sample_rate as usize / 60) / buffers_per_frame;
 
         let rb = AsyncHeapRb::<[f32; 2]>::new(rb_len);
         let (send_rb, rx) = rb.split();
@@ -62,7 +60,6 @@ impl AudioOutput {
             Self {
                 sample_rate,
                 send_rb,
-                wait_for_output,
                 downsample_type,
             },
             rx,

lib/src/processor/memory/mmio/apu.rs

@@ -42,8 +42,6 @@ pub struct Apu {
     vin: VinEnable,
     mixer: Mixer,
     div_apu: u8,
-    buffer: Vec<DacSample>,
-    out_buffer: Vec<[f32; 2]>,
     converter: Downsampler,
     output: AudioOutput,
 }
@@ -55,8 +53,6 @@ pub struct ApuSaveState {
     vin: VinEnable,
     mixer: Mixer,
     div_apu: u8,
-    buffer: Vec<DacSample>,
-    out_buffer: Vec<[f32; 2]>,
 }
 
 impl ApuSaveState {
@@ -67,14 +63,10 @@ impl ApuSaveState {
             vin: apu.vin,
             mixer: apu.mixer,
             div_apu: apu.div_apu,
-            buffer: apu.buffer.clone(),
-            out_buffer: apu.out_buffer.clone(),
         }
     }
 }
 
-const CYCLES_PER_FRAME: usize = 70224;
-
 impl Apu {
     pub fn new(output: AudioOutput) -> Self {
         Self {
@@ -83,8 +75,6 @@ impl Apu {
             vin: VinEnable::default(),
             mixer: Mixer::default(),
             div_apu: 0,
-            buffer: vec![],
-            out_buffer: vec![],
             converter: Downsampler::new(output.sample_rate, output.downsample_type),
             output,
         }
@@ -97,8 +87,6 @@ impl Apu {
             vin: state.vin,
             mixer: state.mixer,
             div_apu: state.div_apu,
-            buffer: state.buffer,
-            out_buffer: state.out_buffer,
             converter: Downsampler::new(output.sample_rate, output.downsample_type),
             output,
         }
@@ -132,8 +120,7 @@ impl Apu {
 
     pub fn tick(&mut self, steps: usize, output: bool) {
         if output {
-            self.buffer.append(
+            for s in izip!(
-                &mut izip!(
                 self.channels.one.tick(steps).into_iter(),
                 self.channels.two.tick(steps).into_iter(),
                 self.channels.three.tick(steps).into_iter(),
@@ -144,13 +131,10 @@ impl Apu {
                 two,
                 three,
                 four,
-                })
+            }) {
-                .collect(),
+                if let Some(next) = self.converter.push(s.mixed(&self.mixer)) {
-            );
+                    executor::block_on(self.output.send_rb.push(next)).unwrap();
-            if self.buffer.len() >= CYCLES_PER_FRAME {
+                }
-                self.next_audio();
-            } else if !self.out_buffer.is_empty() {
-                self.push_audio();
             }
         } else {
             self.channels.one.tick(steps);
@@ -168,34 +152,6 @@ impl Apu {
         (self.channels.one.last & 0xF) | ((self.channels.two.last & 0xF0) << 4)
     }
 
-    fn next_audio(&mut self) {
-        self.out_buffer.append(
-            &mut self.converter.process(
-                self.buffer
-                    .drain(..)
-                    .map(|v| v.mixed(&self.mixer))
-                    .collect::<Vec<[f32; 2]>>(),
-            ),
-        );
-
-        self.push_audio();
-    }
-
-    fn push_audio(&mut self) {
-        let length = if self.output.wait_for_output {
-            self.out_buffer.len()
-        } else {
-            self.out_buffer.len().min(self.output.send_rb.free_len())
-        };
-
-        executor::block_on(
-            self.output
-                .send_rb
-                .push_slice(&self.out_buffer.drain(..length).collect::<Vec<[f32; 2]>>()),
-        )
-        .unwrap();
-    }
-
     pub fn is_buffer_full(&self) -> bool {
         self.output.send_rb.is_full()
     }

lib/src/processor/memory/mmio/apu/downsampler.rs

@@ -55,22 +55,20 @@ impl Downsampler {
         }
     }
 
-    pub fn process(&mut self, signal: Vec<[f32; 2]>) -> Vec<[f32; 2]> {
+    pub fn push(&mut self, signal: [f32; 2]) -> Option<[f32; 2]> {
-        let mut output = vec![];
-        for ref val in signal {
         self.time_accum += 1.;
         if let Some(ref mut averager) = self.average {
-                averager.push(val);
+            averager.push(&signal);
         }
         if self.time_accum >= self.ratio {
             self.time_accum -= self.ratio;
-                output.push(if let Some(ref mut averager) = self.average {
+            Some(if let Some(ref mut averager) = self.average {
                 averager.finish()
             } else {
-                    *val
+                signal
-                });
+            })
+        } else {
+            None
         }
     }
-        output
-    }
 }