Add W12 Opus/network quality profiles

Add a small, named codec-policy picker (Low latency / Balanced / Bad
network) instead of exposing raw Opus knobs. The profile->params mapping
is a pure function (`codec::opus_impl::opus_params`) for unit testing;
profiles tune bitrate, in-band FEC, expected packet-loss, and DTX.

- config: `AudioProfile` enum (serde + Display + ALL + u8 round-trip),
  persisted `audio_profile` field (default Balanced).
- codec: `OpusParams` + pure `opus_params()` + `OpusEncoder::apply_params`
  / `apply_profile`.
- core: new `SetAudioProfile` command (Reliable, no coalesce); a shared
  `AtomicU8` lets the capture thread re-tune the live encoder on a
  mid-call switch and read it at each new call's encoder creation.
- app: Settings "Connection quality" picker in the Audio tab, startup
  config-sync send, and a one-line hint per profile.

No wire-format change (GOSSIP/audio planes untouched). 499 lib tests
green (config + codec mapping/apply tests added), clippy + fmt clean.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/mod.rs

@@ -4,7 +4,7 @@ use crate::audio::clip_player::{
 };
 use crate::audio::eq::{EQ_GAIN_DB_MAX, EQ_GAIN_DB_MIN, EqSettings};
 use crate::audio::{AudioDevice, enumerate_audio_devices};
-use crate::config::{AppConfig, NetworkMode, RecordingMode, RoomLayout};
+use crate::config::{AppConfig, AudioProfile, NetworkMode, RecordingMode, RoomLayout};
 use crate::core::{
     CoreController,
     messages::{CoreCommand, UiEvent},
@@ -377,6 +377,7 @@ pub enum AppMessage {
     /// immediately but does not persist (saved once on release via NoiseGateChanged).
     NoiseGateDragging(f32),
     NetworkModeSelected(NetworkMode),
+    AudioProfileSelected(AudioProfile),
     RecordingModeSelected(RecordingMode),
     /// Choose the friends presence posture (W7): invisible / normal / discoverable.
     PresenceModeSelected(PresenceMode),
@@ -919,6 +920,7 @@ impl Default for AppState {
         let _ = controller.send(CoreCommand::SetInputVolume(config.input_volume));
         let _ = controller.send(CoreCommand::SetOutputVolume(config.output_volume));
         let _ = controller.send(CoreCommand::SetNetworkMode(config.network_mode));
+        let _ = controller.send(CoreCommand::SetAudioProfile(config.audio_profile));
         let _ = controller.send(CoreCommand::SetRecordingMode(config.recording_mode));
         let _ = controller.send(CoreCommand::SetPixelpassPath(config.pixelpass_path.clone()));
         let _ = controller.send(CoreCommand::SetPresenceMode(config.presence_mode));
@@ -2050,6 +2052,12 @@ fn update(state: &mut AppState, message: AppMessage) -> Task<AppMessage> {
             // Applied on the next join, since the endpoint is rebuilt then.
             let _ = state.controller.send(CoreCommand::SetNetworkMode(mode));
         }
+        AppMessage::AudioProfileSelected(profile) => {
+            state.config.audio_profile = profile;
+            state.config.save();
+            // Applies live to the running encoder, and to the next call.
+            let _ = state.controller.send(CoreCommand::SetAudioProfile(profile));
+        }
         AppMessage::RecordingModeSelected(mode) => {
             state.config.recording_mode = mode;
             state.config.save();
@@ -3123,6 +3131,19 @@ fn network_mode_hint(mode: NetworkMode) -> &'static str {
     }
 }
 
+/// One-line explanation of an audio/network profile for the settings picker (W12).
+fn audio_profile_hint(profile: AudioProfile) -> &'static str {
+    match profile {
+        AudioProfile::LowLatency => {
+            "Lowest delay, no loss recovery. Best on a clean LAN or wired link."
+        }
+        AudioProfile::Balanced => "Default: voice quality with light loss recovery.",
+        AudioProfile::BadNetwork => {
+            "Most resilient on a lossy/congested link: extra loss recovery, lower bitrate."
+        }
+    }
+}
+
 /// One-line explanation of a recording mode for the settings picker.
 fn recording_mode_hint(mode: RecordingMode) -> &'static str {
     match mode {
@@ -4981,6 +5002,17 @@ fn view(state: &AppState) -> Element<'_, AppMessage> {
                         control
                     },
                 ].spacing(8).width(iced::Length::Fill),
+                vertical_space(section_gap),
+                section_header("Connection quality"),
+                column![
+                    pick_list(
+                        &AudioProfile::ALL[..],
+                        Some(state.config.audio_profile),
+                        AppMessage::AudioProfileSelected,
+                    ).width(iced::Length::Fill),
+                    text(audio_profile_hint(state.config.audio_profile)).size(11).color(color_subtext),
+                    text("Applies immediately, even mid-call.").size(11).color(color_subtext),
+                ].spacing(4).width(iced::Length::Fill),
             ]
             .spacing(10)
             .width(iced::Length::Fill)

src/codec/opus_impl.rs

@@ -1,5 +1,49 @@
 use crate::codec::{AudioDecoder, AudioEncoder, CodecError};
-use opus::{Application, Channels, Decoder, Encoder};
+use crate::config::AudioProfile;
+use opus::{Application, Bitrate, Channels, Decoder, Encoder};
+
+/// Concrete libopus encoder settings derived from an [`AudioProfile`]. Plain
+/// data, so the profile→params mapping ([`opus_params`]) stays a pure,
+/// unit-testable function (W12).
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct OpusParams {
+    /// Target bitrate in bits/sec.
+    pub bitrate: i32,
+    /// Enable in-band forward error correction (loss redundancy in the bitstream).
+    pub inband_fec: bool,
+    /// Expected packet-loss percentage (0..=100); tunes how much FEC libopus adds.
+    pub packet_loss_perc: i32,
+    /// Discontinuous transmission: stop sending during silence to save bandwidth.
+    pub dtx: bool,
+}
+
+/// Map a named profile to concrete Opus parameters. Pure — the W12 testable seam.
+///
+/// `BadNetwork` deliberately runs a *lower* bitrate than `Balanced`: in-band FEC
+/// redundancy is carried inside the same bitstream, so trimming the base bitrate
+/// leaves headroom for the redundancy on a congested link.
+pub fn opus_params(profile: AudioProfile) -> OpusParams {
+    match profile {
+        AudioProfile::LowLatency => OpusParams {
+            bitrate: 24_000,
+            inband_fec: false,
+            packet_loss_perc: 0,
+            dtx: false,
+        },
+        AudioProfile::Balanced => OpusParams {
+            bitrate: 32_000,
+            inband_fec: true,
+            packet_loss_perc: 10,
+            dtx: false,
+        },
+        AudioProfile::BadNetwork => OpusParams {
+            bitrate: 20_000,
+            inband_fec: true,
+            packet_loss_perc: 25,
+            dtx: true,
+        },
+    }
+}
 
 pub struct OpusEncoder {
     encoder: Encoder,
@@ -17,6 +61,29 @@ impl OpusEncoder {
             .map_err(|e| CodecError::Init(format!("Failed to create Opus encoder: {}", e)))?;
         Ok(Self { encoder })
     }
+
+    /// Apply concrete codec parameters to the live encoder. Safe to call between
+    /// frames, so the user can switch profile mid-call.
+    pub fn apply_params(&mut self, params: &OpusParams) -> Result<(), CodecError> {
+        self.encoder
+            .set_bitrate(Bitrate::Bits(params.bitrate))
+            .map_err(|e| CodecError::Init(format!("set_bitrate: {}", e)))?;
+        self.encoder
+            .set_inband_fec(params.inband_fec)
+            .map_err(|e| CodecError::Init(format!("set_inband_fec: {}", e)))?;
+        self.encoder
+            .set_packet_loss_perc(params.packet_loss_perc)
+            .map_err(|e| CodecError::Init(format!("set_packet_loss_perc: {}", e)))?;
+        self.encoder
+            .set_dtx(params.dtx)
+            .map_err(|e| CodecError::Init(format!("set_dtx: {}", e)))?;
+        Ok(())
+    }
+
+    /// Apply a named [`AudioProfile`] (shorthand for `apply_params(&opus_params(p))`).
+    pub fn apply_profile(&mut self, profile: AudioProfile) -> Result<(), CodecError> {
+        self.apply_params(&opus_params(profile))
+    }
 }
 
 impl AudioEncoder for OpusEncoder {
@@ -101,6 +168,47 @@ impl AudioDecoder for OpusDecoder {
 mod tests {
     use super::*;
 
+    #[test]
+    fn test_opus_params_mapping() {
+        let low = opus_params(AudioProfile::LowLatency);
+        let bal = opus_params(AudioProfile::Balanced);
+        let bad = opus_params(AudioProfile::BadNetwork);
+
+        // LowLatency has no loss redundancy; the other two do.
+        assert!(!low.inband_fec);
+        assert_eq!(low.packet_loss_perc, 0);
+        assert!(bal.inband_fec);
+        assert!(bad.inband_fec);
+
+        // BadNetwork is the only profile that enables DTX, and it expects the
+        // heaviest loss.
+        assert!(bad.dtx);
+        assert!(!low.dtx && !bal.dtx);
+        assert!(bad.packet_loss_perc > bal.packet_loss_perc);
+
+        // BadNetwork trims base bitrate to make room for FEC redundancy.
+        assert!(bad.bitrate < bal.bitrate);
+
+        // All bitrates are sane positive voice rates.
+        for p in [low, bal, bad] {
+            assert!(p.bitrate > 0 && p.bitrate <= 64_000);
+            assert!((0..=100).contains(&p.packet_loss_perc));
+        }
+    }
+
+    #[test]
+    fn test_apply_profile_sets_bitrate() {
+        let mut encoder = OpusEncoder::new(48000, Channels::Mono, Application::Voip).unwrap();
+        // Every profile applies cleanly to a real encoder...
+        for profile in AudioProfile::ALL {
+            encoder.apply_profile(profile).unwrap();
+        }
+        // ...and the last-applied bitrate is reflected by the encoder.
+        encoder.apply_profile(AudioProfile::Balanced).unwrap();
+        let want = opus_params(AudioProfile::Balanced).bitrate;
+        assert_eq!(encoder.encoder.get_bitrate().unwrap(), Bitrate::Bits(want));
+    }
+
     #[test]
     fn test_round_trip() {
         let mut encoder = OpusEncoder::new(48000, Channels::Mono, Application::Voip).unwrap();

src/config.rs

@@ -93,6 +93,60 @@ impl std::fmt::Display for RecordingMode {
     }
 }
 
+/// Named Opus encoder / network-resilience policy (W12). The user picks a
+/// profile instead of raw codec knobs; the concrete libopus parameters live in
+/// `codec::opus_impl::opus_params`. Applies live to the running encoder.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
+pub enum AudioProfile {
+    /// Lowest mouth-to-ear delay: modest bitrate, no FEC redundancy. Best on a
+    /// clean LAN / low-loss link where added latency matters more than loss.
+    LowLatency,
+    /// Sensible default: voice bitrate with in-band FEC for light packet loss.
+    #[default]
+    Balanced,
+    /// Maximum resilience on a lossy/congested link: in-band FEC tuned for heavy
+    /// loss plus DTX, at a lower bitrate to leave headroom for the redundancy.
+    BadNetwork,
+}
+
+impl AudioProfile {
+    /// All variants, in picker display order.
+    pub const ALL: [AudioProfile; 3] = [
+        AudioProfile::LowLatency,
+        AudioProfile::Balanced,
+        AudioProfile::BadNetwork,
+    ];
+
+    /// Compact discriminant for handing the profile to the capture thread via an
+    /// atomic. Pairs with [`AudioProfile::from_u8`].
+    pub fn as_u8(self) -> u8 {
+        match self {
+            AudioProfile::LowLatency => 0,
+            AudioProfile::Balanced => 1,
+            AudioProfile::BadNetwork => 2,
+        }
+    }
+
+    /// Inverse of [`AudioProfile::as_u8`]; unknown values fall back to the default.
+    pub fn from_u8(v: u8) -> AudioProfile {
+        match v {
+            0 => AudioProfile::LowLatency,
+            2 => AudioProfile::BadNetwork,
+            _ => AudioProfile::Balanced,
+        }
+    }
+}
+
+impl std::fmt::Display for AudioProfile {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(match self {
+            AudioProfile::LowLatency => "Low latency",
+            AudioProfile::Balanced => "Balanced",
+            AudioProfile::BadNetwork => "Bad network",
+        })
+    }
+}
+
 impl std::fmt::Display for RoomLayout {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         f.write_str(match self {
@@ -199,6 +253,10 @@ pub struct AppConfig {
     pub clip_volume_universal: bool,
     #[serde(default)]
     pub network_mode: NetworkMode,
+    /// Opus encoder / network-resilience profile (W12). Applies live to the
+    /// running encoder; default `Balanced`.
+    #[serde(default)]
+    pub audio_profile: AudioProfile,
     /// Presence posture for the friends idle listener (W7): invisible / normal /
     /// discoverable. Default `Normal` = answer friends only, no DNS beacon.
     #[serde(default)]
@@ -380,6 +438,7 @@ impl Default for AppConfig {
             show_player_bar: true,
             clip_volume_universal: true,
             network_mode: NetworkMode::default(),
+            audio_profile: AudioProfile::default(),
             presence_mode: crate::presence::PresenceMode::default(),
             echo_cancellation_enabled: false,
             notifications_enabled: true,
@@ -1019,6 +1078,38 @@ mod tests {
         assert_ne!(display_0, display_2);
     }
 
+    #[test]
+    fn test_audio_profile() {
+        // Default is Balanced.
+        assert_eq!(AudioProfile::default(), AudioProfile::Balanced);
+
+        // ALL holds the three variants.
+        assert_eq!(AudioProfile::ALL.len(), 3);
+        assert!(AudioProfile::ALL.contains(&AudioProfile::LowLatency));
+        assert!(AudioProfile::ALL.contains(&AudioProfile::Balanced));
+        assert!(AudioProfile::ALL.contains(&AudioProfile::BadNetwork));
+
+        // as_u8 / from_u8 round-trip every variant, and unknown bytes fall back
+        // to the default rather than panicking.
+        for p in AudioProfile::ALL {
+            assert_eq!(AudioProfile::from_u8(p.as_u8()), p);
+        }
+        assert_eq!(AudioProfile::from_u8(99), AudioProfile::Balanced);
+
+        // serde round-trips, and Display strings are non-empty + distinct.
+        let mut labels = Vec::new();
+        for p in AudioProfile::ALL {
+            let s = serde_json::to_string(&p).unwrap();
+            assert_eq!(serde_json::from_str::<AudioProfile>(&s).unwrap(), p);
+            let label = p.to_string();
+            assert!(!label.is_empty());
+            labels.push(label);
+        }
+        labels.sort();
+        labels.dedup();
+        assert_eq!(labels.len(), 3);
+    }
+
     #[test]
     fn test_unknown_field_tolerance() {
         // Unknown/extra field tolerance: a config JSON containing an extra unrecognized key should still deserialize.

src/core/messages.rs

@@ -1,4 +1,4 @@
-use crate::config::{NetworkMode, RecordingMode};
+use crate::config::{AudioProfile, NetworkMode, RecordingMode};
 use crate::friends::Friend;
 use crate::network::PeerState;
 use crate::presence::{FriendPresence, PresenceMode};
@@ -56,6 +56,10 @@ pub enum CoreCommand {
     /// Set the relay/discovery posture. Takes effect on the next room join,
     /// since the endpoint is (re)built then.
     SetNetworkMode(NetworkMode),
+    /// Set the Opus encoder / network-resilience profile (W12). Applies live to
+    /// the running capture encoder, and to the next call's encoder. Sent at
+    /// startup from config and whenever the user changes it.
+    SetAudioProfile(AudioProfile),
     /// Start/stop recording the call to a local WAV (your mic + the incoming
     /// mix). No-op start if already recording / not in a call.
     SetRecording(bool),
@@ -212,6 +216,7 @@ pub fn delivery_class(cmd: &CoreCommand) -> DeliveryClass {
             input_device: _,
         }
         | CoreCommand::SetNetworkMode(_)
+        | CoreCommand::SetAudioProfile(_)
         | CoreCommand::SetRecording(_)
         | CoreCommand::SetRecordingMode(_)
         | CoreCommand::SendChat(_)
@@ -292,6 +297,7 @@ pub fn coalesce_key(cmd: &CoreCommand) -> Option<CoalesceKey> {
             input_device: _,
         }
         | CoreCommand::SetNetworkMode(_)
+        | CoreCommand::SetAudioProfile(_)
         | CoreCommand::SetRecording(_)
         | CoreCommand::SetRecordingMode(_)
         | CoreCommand::SendChat(_)
@@ -574,6 +580,7 @@ mod tests {
             },
             CoreCommand::SetPeerMuted(peer, true),
             CoreCommand::SetPresenceMode(PresenceMode::Normal),
+            CoreCommand::SetAudioProfile(crate::config::AudioProfile::BadNetwork),
             CoreCommand::SendChat("hello".to_string()),
         ];
 

src/core/mod.rs

@@ -17,7 +17,7 @@ use crate::network::{
 };
 
 use crate::audio::multitrack::MultitrackRecorder;
-use crate::config::{NetworkMode, RecordingMode};
+use crate::config::{AudioProfile, NetworkMode, RecordingMode};
 use crate::presence::PresenceMode;
 use iroh::{
     Endpoint, EndpointAddr, EndpointId, RelayMode, SecretKey, endpoint::presets, protocol::Router,
@@ -1162,6 +1162,12 @@ async fn run_core_loop(
     // App-internal capture/playback gains (f32 bits), live-read by the audio loops.
     let input_gain = Arc::new(std::sync::atomic::AtomicU32::new(1.0f32.to_bits()));
     let output_gain = Arc::new(std::sync::atomic::AtomicU32::new(1.0f32.to_bits()));
+    // Opus encoder profile (W12) as a discriminant, live-read by the capture
+    // thread so a mid-call profile switch re-tunes the running encoder. Set from
+    // config via the GUI's startup `SetAudioProfile`; defaults to Balanced.
+    let audio_profile = Arc::new(std::sync::atomic::AtomicU8::new(
+        AudioProfile::default().as_u8(),
+    ));
     // Call recording: an optional live recorder (mic FIFO + WAV writer), shared
     // by the capture thread (pushes mic) and the mixer task (writes mix frames).
     // `is_recording` is a fast-path gate so the audio loops only take the lock
@@ -1740,6 +1746,7 @@ async fn run_core_loop(
                 let is_recording_capture = is_recording.clone();
                 let multitrack_capture = multitrack.clone();
                 let is_multitrack_capture = is_multitrack.clone();
+                let audio_profile_capture = audio_profile.clone();
 
                 let capture_thread = std::thread::spawn(move || {
                     use opus::{Application, Channels};
@@ -1751,6 +1758,13 @@ async fn run_core_loop(
                                 return;
                             }
                         };
+                    // Tune the encoder to the configured profile (W12), then track
+                    // the live discriminant so a mid-call switch re-applies it.
+                    let mut current_profile =
+                        AudioProfile::from_u8(audio_profile_capture.load(Ordering::Relaxed));
+                    if let Err(e) = encoder.apply_profile(current_profile) {
+                        crate::log_msg(&format!("Opus profile apply failed: {:?}", e));
+                    }
                     // Per-sender packet sequence number, prepended to every frame so
                     // receivers can reorder and conceal loss. Wraps after ~years.
                     let mut seq: u32 = 0;
@@ -1763,6 +1777,14 @@ async fn run_core_loop(
                     let mut mic_meter = MicLevelMeter::new();
 
                     while let Ok(mut pcm) = capture_rx.recv() {
+                        // Re-tune the encoder if the user switched profile mid-call.
+                        // Cheap atomic load per frame; only reconfigures on change.
+                        let want =
+                            AudioProfile::from_u8(audio_profile_capture.load(Ordering::Relaxed));
+                        if want != current_profile && encoder.apply_profile(want).is_ok() {
+                            current_profile = want;
+                        }
+
                         // Apply the input gain first so the meter, gate, and what we
                         // transmit all reflect the same (gained) signal.
                         apply_volume(
@@ -2682,6 +2704,13 @@ async fn run_core_loop(
                 }
             }
 
+            CoreCommand::SetAudioProfile(profile) => {
+                // Publish the new profile to the capture thread (W12). It picks up
+                // the change on its next frame and re-tunes the live encoder; a
+                // call that starts later reads the same atomic at encoder creation.
+                audio_profile.store(profile.as_u8(), Ordering::Relaxed);
+            }
+
             CoreCommand::RegenerateIdentity => {
                 // Mint + persist a fresh identity, discarding the old one. The
                 // persistent endpoint is rebuilt with the new key (now if idle, else