[aud] Use Audio queue

README.md

@@ -20,7 +20,7 @@ Chip 8 emulator/interpreter.
   - [X] Timer
   - [X] Super chip8 compatibility.
 - [X] Audio
-  - Audio seems to be broken on my device. I will check with other devices.
+  - Audio seems to stutter, but working
 - [X] Keyboard
 
 ### More information on CHIP-8

src/device/timer.rs

@@ -43,7 +43,7 @@ impl TimerManager {
                         *timer_lock -= 1;
                     }
                     if *sound_lock > 0 {
-                        log::info!("Beep!");
+                        log::trace!("Beep!");
                         *sound_lock -= 1;
                     }
                 }

src/main.rs

@@ -21,7 +21,7 @@ use crate::device::Device;
 use crate::device::keyboard::Keyboard;
 use crate::util::EmulatorResult;
 use crate::kb_map::get_key_index;
-use crate::sdl_audio_adapter::SquareWave;
+use crate::sdl_audio_adapter::SdlAudioAdapter;
 use crate::sdl_graphics_adapter::SdlGraphicsAdapter;
 use crate::sdl_keyboard_adapter::SdlKeyboardAdapter;
 
@@ -41,9 +41,11 @@ fn main() -> EmulatorResult<()> {
     let mut timer = TimerManager::new();
 
 
-    let audio_state = timer.start();
-    let (mut canvas, mut event_pump) = try_initiate_sdl(audio_state,draw_scale)?;
+    let (mut canvas, mut event_pump,audio_queue) = try_initiate_sdl(draw_scale)?;
 
+    let audio_state = timer.start();
+
+    let mut sdl_aud_adapter = SdlAudioAdapter::new(audio_state,440.0,0.5,audio_queue);
     
     
     let (frame_buffer_for_display, frame_buffer_for_device) = get_frame_buffer_references();
@@ -91,7 +93,7 @@ fn main() -> EmulatorResult<()> {
             sdl_graphics_adapter.draw_screen(lock, &mut canvas)?;
         }
         canvas.present();
-
+        sdl_aud_adapter.process_push_audio()?;
         // 60fps - small offset to consider for cpu cycle time
         thread::sleep(Duration::new(0, 1_000_000_000u32 / 60));
     }
@@ -139,22 +141,18 @@ fn load_rom(rom_file_location: String) -> [u8; ROM_SIZE] {
     rom_slice
 }
 
-fn try_initiate_sdl(audio_state: Arc<Mutex<u8>>, draw_scale: f32) -> EmulatorResult<(WindowCanvas, EventPump)> {
+fn try_initiate_sdl(draw_scale: f32) -> EmulatorResult<(WindowCanvas, EventPump, AudioQueue<f32>)> {
     let sdl_context = sdl2::init().unwrap();
     let video_subsystem = sdl_context.video().unwrap();
     let audio_subsystem = sdl_context.audio().unwrap();
     let wanted_spec = AudioSpecDesired {
         channels: Some(1),
         samples: None,
-        freq: Some(44100),
+        freq: Some(SdlAudioAdapter::SAMPLING_FREQ),
     };
 
-    let device = audio_subsystem.open_playback(None, &wanted_spec, |spec| {
-        // initialize the audio callback
-        SquareWave ::new(audio_state,440.0/spec.freq as f32,0.5)
-    }).unwrap();
-    device.resume();
-        
+    let audio_queue = audio_subsystem.open_queue::<f32,_>(None, &wanted_spec)?;
+
     let window_width = (Device::FRAME_BUFFER_WIDTH as f32 * draw_scale) as u32;
     let window_height = (Device::FRAME_BUFFER_HEIGHT as f32 * draw_scale) as u32;
 
@@ -169,8 +167,7 @@ fn try_initiate_sdl(audio_state: Arc<Mutex<u8>>, draw_scale: f32) -> EmulatorRes
     canvas.clear();
     canvas.present();
     let event_pump = sdl_context.event_pump()?;
-    Ok((canvas, event_pump
-    ))
+    Ok((canvas, event_pump,audio_queue))
 }
 
 

src/sdl_audio_adapter.rs

@@ -1,46 +1,59 @@
-use std::sync::{Arc, Mutex, RwLock};
-use log::warn;
-use sdl2::audio::AudioCallback;
+use std::sync::{Arc, Mutex};
+use sdl2::audio::AudioQueue;
+use crate::util::EmulatorResult;
 
-pub struct SquareWave {
+pub struct SdlAudioAdapter {
     sound_timer: Arc<Mutex<u8>>,
     phase_inc: f32,
     phase: f32,
     volume: f32,
+    audio_queue: AudioQueue<f32>,
+    buf: Vec<f32>,
 }
 
-impl SquareWave {
+/// An Audio adapter using `AudioQueue`.
+impl SdlAudioAdapter {
+    pub const SAMPLING_FREQ:i32 = 15360;
+    pub const SAMPLES_PER_FRAME: usize = Self::SAMPLING_FREQ as usize / 60 + 2;
     pub fn new(sound_timer: Arc<Mutex<u8>>,
-               phase_inc: f32,
-               volume: f32)->SquareWave {
-        SquareWave {
+               freq: f32,
+               volume: f32,
+               audio_queue: AudioQueue<f32>) -> SdlAudioAdapter {
+        audio_queue.resume();
+        SdlAudioAdapter {
             sound_timer,
+            buf: vec![0f32; Self::SAMPLES_PER_FRAME],
             phase: 0f32,
-            phase_inc,
+            phase_inc: freq/Self::SAMPLING_FREQ as f32,
             volume,
+            audio_queue,
         }
     }
-}
+    pub fn process_push_audio(&mut self) -> EmulatorResult<()> {
+        // fill the audio vector.
+        let sound_timer = {
+            let sound_timer = self.sound_timer.lock().expect("Could not lock to play audio");
+            sound_timer.clone()
+        };
+        if sound_timer>0 {
+            self.fill_audio();
+            self.audio_queue.queue_audio(&self.buf)?;
+        }
+        Ok(())
+    }
 
-impl AudioCallback for SquareWave {
-    type Channel = f32;
+    fn fill_audio(&mut self) {
+        let out = &mut self.buf;
 
-    fn callback(&mut self, out: &mut [f32]) {
-        let sound_timer = self.sound_timer.lock().expect("Could not lock to play audio");
-        let sound_timer = sound_timer.clone();
-        // log::info!("Processing audio buffer length {}",out.len());
         // Generate a square wave
         for x in out.iter_mut() {
-            *x = if sound_timer > 0 {
-                if self.phase <= 0.5 {
-                    self.volume
-                } else {
-                    -self.volume
-                }
+            *x = if self.phase <= 0.5 {
+                self.volume
             } else {
-                0f32
+                -self.volume
             };
+
             self.phase = (self.phase + self.phase_inc) % 1.0;
         }
     }
-}
+}