Add a default noise floor. (#13)

(Turns out not) Pretty simple, if the average amplitude is under a certain value clear
out the buffer! The value I chose (.001) was an arbitrary value I got
from printf debugging. I was able to show that this worked pretty well
on the desktop session. Hopefully we'll add this to the settings page at
some point.

Once the app has been under that threshold for more than 200ms, we stop transmitting and send a terminator packet.

Reviewed-on: #13
Reviewed-by: restitux <restitux@ohea.xyz>

gui/src/imp/native_audio.rs

@@ -1,4 +1,4 @@
-use crate::effects::{AudioProcessor, AudioProcessorSender};
+use crate::effects::{AudioProcessor, AudioProcessorSender, TransmitState};
 use color_eyre::eyre::{eyre, Error};
 use cpal::traits::{DeviceTrait, HostTrait, StreamTrait as _};
 use futures::io::{AsyncRead, AsyncWrite};
@@ -23,6 +23,31 @@ pub struct AudioSystem {
 const SAMPLE_RATE: u32 = 48_000;
 const PACKET_SAMPLES: u32 = 960;
 
+fn encode_and_send(
+    state: TransmitState,
+    output_buffer: &mut Vec<f32>,
+    encoder: &mut opus::Encoder,
+    each: &mut impl FnMut(Vec<u8>, bool),
+) {
+    let (is_terminator, should_encode) = match state {
+        TransmitState::Silent => return,
+        TransmitState::Transmitting => (false, output_buffer.len() >= PACKET_SAMPLES as usize),
+        TransmitState::Terminator => {
+            output_buffer.resize(PACKET_SAMPLES as usize, 0.0);
+            (true, true)
+        }
+    };
+
+    if should_encode {
+        let remainder = output_buffer.split_off(PACKET_SAMPLES as usize);
+        let frame = replace(output_buffer, remainder);
+        match encoder.encode_vec_float(&frame, frame.len() * 2) {
+            Ok(encoded) => each(encoded, is_terminator),
+            Err(e) => error!("error encoding {} samples: {e:?}", frame.len()),
+        }
+    }
+}
+
 type Buffer = Arc<Mutex<dasp_ring_buffer::Bounded<Vec<i16>>>>;
 
 impl AudioSystem {
@@ -79,7 +104,7 @@ impl AudioSystem {
 
     pub fn start_recording(
         &mut self,
-        mut each: impl FnMut(Vec<u8>) + Send + 'static,
+        mut each: impl FnMut(Vec<u8>, bool) + Send + 'static,
     ) -> Result<(), Error> {
         let config = self.choose_config(self.input.supported_input_configs()?)?;
         info!(
@@ -97,20 +122,8 @@ impl AudioSystem {
             if let Some(new_processor) = processors.take() {
                 current_processor = new_processor;
             }
-            current_processor.process(frame, config.channels as usize, &mut output_buffer);
-            if output_buffer.len() < PACKET_SAMPLES as usize {
-                return;
-            }
-            let remainder = output_buffer.split_off(PACKET_SAMPLES as usize);
-            let frame = replace(&mut output_buffer, remainder);
-            match encoder.encode_vec_float(&frame, frame.len() * 2) {
-                Ok(buf) => {
-                    each(buf);
-                }
-                Err(e) => {
-                    error!("error encoding {} samples: {e:?}", frame.len());
-                }
-            }
+            let state = current_processor.process(frame, config.channels as usize, &mut output_buffer);
+            encode_and_send(state, &mut output_buffer, &mut encoder, &mut each);
         };
 
         match self

gui/src/imp/web.rs

@@ -1,6 +1,7 @@
 use crate::app::Command;
-use crate::effects::{AudioProcessor, AudioProcessorSender};
+use crate::effects::{AudioProcessor, AudioProcessorSender, TransmitState};
 use color_eyre::eyre::{bail, eyre, Error};
+use crossbeam::atomic::AtomicCell;
 use dioxus::prelude::*;
 use futures::{AsyncRead, AsyncWrite};
 use gloo_timers::future::TimeoutFuture;
@@ -9,6 +10,7 @@ use mumble_protocol::control::ClientControlCodec;
 use mumble_web2_common::{ClientConfig, ServerStatus};
 use reqwest::Url;
 use std::future::Future;
+use std::sync::Arc;
 use std::time::Duration;
 use tracing::level_filters::LevelFilter;
 use tracing::{debug, error, info, instrument};
@@ -118,7 +120,10 @@ impl AudioSystem {
         self.processors.store(Some(processor))
     }
 
-    pub fn start_recording(&mut self, each: impl FnMut(Vec<u8>) + 'static) -> Result<(), Error> {
+    pub fn start_recording(
+        &mut self,
+        each: impl FnMut(Vec<u8>, bool) + 'static,
+    ) -> Result<(), Error> {
         let audio_context_worklet = self.webctx.clone();
         let processors = self.processors.clone();
         spawn(async move {
@@ -222,22 +227,26 @@ impl PromiseExt for Promise {
     }
 }
 
-fn process_audio(frame: &JsValue, processor: &mut AudioProcessor) {
+fn process_audio(frame: &JsValue, processor: &mut AudioProcessor) -> TransmitState {
     let Ok(samples) = Reflect::get(&frame, &"data".into()) else {
-        return;
+        return TransmitState::Silent;
     };
     let Ok(samples) = samples.dyn_into::<Float32Array>() else {
-        return;
+        return TransmitState::Silent;
     };
     let input = samples.to_vec();
     let mut output = Vec::with_capacity(input.len());
-    processor.process(&input, 1, &mut output);
-    samples.copy_from(&output);
+    let state = processor.process(&input, 1, &mut output);
+    if !output.is_empty() {
+        samples.copy_from(&output);
+    }
+
+    state
 }
 
 async fn run_encoder_worklet(
     audio_context: &AudioContext,
-    mut each: impl FnMut(Vec<u8>) + 'static,
+    mut each: impl FnMut(Vec<u8>, bool) + 'static,
     processors: AudioProcessorSender,
 ) -> Result<AudioWorkletNode, Error> {
     let constraints = MediaStreamConstraints::new();
@@ -262,12 +271,19 @@ async fn run_encoder_worklet(
     let encoder_error: Closure<dyn FnMut(JsValue)> =
         Closure::new(|e| error!("error encoding audio {:?}", e));
 
+    // Shared state to signal terminator between onmessage and output closures
+    // The output closure runs asynchronously after encoding completes
+    let pending_terminator = Arc::new(AtomicCell::new(false));
+    let pending_terminator_output = pending_terminator.clone();
+
     // This knows what MediaStreamTrackGenerator to use as it closes around it
     let output: Closure<dyn FnMut(EncodedAudioChunk)> =
         Closure::new(move |audio_data: EncodedAudioChunk| {
             let mut array = vec![0u8; audio_data.byte_length() as usize];
             audio_data.copy_to_with_u8_slice(&mut array);
-            each(array);
+            // Check if this frame was marked as a terminator
+            let is_terminator = pending_terminator_output.swap(false);
+            each(array, is_terminator);
         });
 
     let audio_encoder = AudioEncoder::new(&AudioEncoderInit::new(
@@ -294,8 +310,19 @@ async fn run_encoder_worklet(
         }
 
         let frame = event.data();
-        process_audio(&frame, &mut current_processor);
+        let state = process_audio(&frame, &mut current_processor);
 
+        match state {
+            TransmitState::Silent => {
+                // Don't encode or send anything
+                return;
+            }
+            TransmitState::Transmitting => (), // Normal transmission
+            TransmitState::Terminator => {
+                // Mark this as a terminator before encoding
+                pending_terminator.store(true);
+            }
+        }
         match AudioData::new(frame.unchecked_ref()) {
             Ok(data) => {
                 let _ = audio_encoder.encode(&data);