From bc65445af44a335a0586a393c792614330258249 Mon Sep 17 00:00:00 2001
From: Eskil Queseth <eskilq@kth.se>
Date: Sat, 12 Jun 2021 02:30:01 +0200
Subject: simplify audio output infrastructure

---
 mumd/src/audio/input.rs | 79 +++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 67 insertions(+), 12 deletions(-)

(limited to 'mumd/src/audio/input.rs')

diff --git a/mumd/src/audio/input.rs b/mumd/src/audio/input.rs
index e45ff27..162dd2c 100644
--- a/mumd/src/audio/input.rs
+++ b/mumd/src/audio/input.rs
@@ -8,20 +8,49 @@ use crate::error::{AudioError, AudioStream};
 use crate::state::StatePhase;
 
 pub fn callback<T: Sample>(
-    mut input_sender: futures_channel::mpsc::Sender<f32>,
+    mut input_sender: futures_channel::mpsc::Sender<Vec<u8>>,
+    transformers: Vec<Box<dyn Fn(&mut [f32]) -> Option<&mut [f32]> + Send + 'static>>,
+    frame_size: u32,
+    sample_rate: u32,
+    channels: u16,
     input_volume_receiver: watch::Receiver<f32>,
     phase_watcher: watch::Receiver<StatePhase>,
 ) -> impl FnMut(&[T], &InputCallbackInfo) + Send + 'static {
+    let buffer_size = (sample_rate * frame_size / 400) as usize;
+    let mut opus_encoder = opus::Encoder::new(
+            sample_rate,
+            match channels {
+                1 => opus::Channels::Mono,
+                2 => opus::Channels::Stereo,
+                _ => unimplemented!("Only 1 or 2 channels supported, got {}", channels),
+            },
+            opus::Application::Voip,
+        )
+        .unwrap();
+    let mut buffer = Vec::with_capacity(buffer_size);
+
     move |data: &[T], _info: &InputCallbackInfo| {
         if !matches!(&*phase_watcher.borrow(), StatePhase::Connected(_)) {
             return;
         }
         let input_volume = *input_volume_receiver.borrow();
-        for sample in data.iter().map(|e| e.to_f32()).map(|e| e * input_volume) {
-            if let Err(_e) = input_sender.try_send(sample) {
-                warn!("Error sending audio: {}", _e);
+        let mut data = data.iter().map(|e| e.to_f32()).map(|e| e * input_volume);
+
+        while buffer.len() + data.len() > buffer_size {
+            buffer.extend(data.by_ref().take(buffer_size - buffer.len()));
+            let encoded = transformers
+                .iter()
+                .try_fold(&mut buffer[..], |acc, e| e(acc))
+                .map(|buf| opus_encoder.encode_vec_float(&*buf, buffer_size).unwrap());
+
+            if let Some(encoded) = encoded {
+                if let Err(e) = input_sender.try_send(encoded) {
+                    warn!("Error sending audio: {}", e);
+                }
             }
+            buffer.clear();
         }
+        buffer.extend(data);
     }
 }
 
@@ -29,13 +58,13 @@ pub trait AudioInputDevice {
     fn play(&self) -> Result<(), AudioError>;
     fn pause(&self) -> Result<(), AudioError>;
     fn set_volume(&self, volume: f32);
-    fn sample_receiver(&mut self) -> futures_channel::mpsc::Receiver<f32>;
+    fn sample_receiver(&mut self) -> Option<futures_channel::mpsc::Receiver<Vec<u8>>>;
     fn num_channels(&self) -> usize;
 }
 
 pub struct DefaultAudioInputDevice {
     stream: cpal::Stream,
-    sample_receiver: Option<futures_channel::mpsc::Receiver<f32>>,
+    sample_receiver: Option<futures_channel::mpsc::Receiver<Vec<u8>>>,
     volume_sender: watch::Sender<f32>,
     channels: u16,
 }
@@ -44,6 +73,7 @@ impl DefaultAudioInputDevice {
     pub fn new(
         input_volume: f32,
         phase_watcher: watch::Receiver<StatePhase>,
+        frame_size: u32,
     ) -> Result<Self, AudioError> {
         let sample_rate = SampleRate(SAMPLE_RATE);
 
@@ -73,20 +103,46 @@ impl DefaultAudioInputDevice {
 
         let (volume_sender, input_volume_receiver) = watch::channel::<f32>(input_volume);
 
+        let transformers = vec![];
+
         let input_stream = match input_supported_sample_format {
             SampleFormat::F32 => input_device.build_input_stream(
                 &input_config,
-                callback::<f32>(sample_sender, input_volume_receiver, phase_watcher),
+                callback::<f32>(
+                    sample_sender, 
+                    transformers, 
+                    frame_size, 
+                    SAMPLE_RATE, 
+                    input_config.channels,
+                    input_volume_receiver, 
+                    phase_watcher
+                ),
                 err_fn,
             ),
             SampleFormat::I16 => input_device.build_input_stream(
                 &input_config,
-                callback::<i16>(sample_sender, input_volume_receiver, phase_watcher),
+                callback::<i16>(
+                    sample_sender, 
+                    transformers, 
+                    frame_size, 
+                    SAMPLE_RATE, 
+                    input_config.channels,
+                    input_volume_receiver, 
+                    phase_watcher
+                ),
                 err_fn,
             ),
             SampleFormat::U16 => input_device.build_input_stream(
                 &input_config,
-                callback::<u16>(sample_sender, input_volume_receiver, phase_watcher),
+                callback::<u16>(
+                    sample_sender, 
+                    transformers, 
+                    frame_size, 
+                    SAMPLE_RATE, 
+                    input_config.channels,
+                    input_volume_receiver, 
+                    phase_watcher
+                ),
                 err_fn,
             ),
         }
@@ -116,9 +172,8 @@ impl AudioInputDevice for DefaultAudioInputDevice {
     fn set_volume(&self, volume: f32) {
         self.volume_sender.send(volume).unwrap();
     }
-    fn sample_receiver(&mut self) -> futures_channel::mpsc::Receiver<f32> {
-        let ret = self.sample_receiver.take();
-        ret.unwrap()
+    fn sample_receiver(&mut self) -> Option<futures_channel::mpsc::Receiver<Vec<u8>>> {
+        self.sample_receiver.take()
     }
     fn num_channels(&self) -> usize {
         self.channels as usize
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