feat(audio): multitrack stem recording — Stage 2 (wire into the mixer)

Wires MultitrackRecorder into the live audio path, behind a recording_mode.

- config: RecordingMode { Mixed, Multitrack, Both } + AppConfig.recording_mode
  (serde-default Mixed, back-compat); CoreCommand::SetRecordingMode, sent at
  app startup from config.
- multitrack.rs: mic now arrives async via push_mic into an internal FIFO,
  drained one frame per end_cycle (mirrors recorder.rs) so the mic track tracks
  the cycle clock; added dir() accessor. mic is a plain WavWriter now.
- core: parallel `multitrack` slot + `is_multitrack` fast-path gate (exactly one
  of the mixed/multitrack recorders is active). SetRecording start branches on
  mode: Mixed → single-file Recorder (unchanged); Multitrack/Both → a per-session
  dir, MultitrackRecorder, and registers everyone already in the room (named,
  silence-aligned from t=0). The mixer taps each peer's RAW frame (pre-volume/
  mute/limiter) into stems and writes peer stems + mix (Both) + end_cycle per
  cycle; the capture thread pushes mic to whichever recorder; PeerJoined adds a
  late joiner's stem track. stop_recording finalizes both.

No UI yet to pick the mode (Stage 3) — defaults to Mixed, so behaviour is
unchanged until then; set recording_mode in config.json to exercise stems.
168 lib tests, clippy --all-targets clean.

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

src/app/mod.rs

@@ -267,6 +267,7 @@ 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::SetRecordingMode(config.recording_mode));
         let _ = controller.send(CoreCommand::SetPixelpassPath(config.pixelpass_path.clone()));
         let pixelpass_available =
             crate::screenshare::is_available(config.pixelpass_path.as_deref());

src/audio/multitrack.rs

@@ -12,7 +12,7 @@
 //! This module is pure plumbing over [`WavWriter`]: no audio decode, no
 //! networking, no realtime work. The mixer (a non-RT task) drives it.
 
-use std::collections::HashMap;
+use std::collections::{HashMap, VecDeque};
 use std::io;
 use std::path::{Path, PathBuf};
 
@@ -25,6 +25,11 @@ use crate::core::jitter::FRAME_SAMPLES;
 /// long-running call can't trigger a single multi-hundred-MB allocation.
 const SILENCE_CHUNK: usize = FRAME_SAMPLES * 256;
 
+/// Cap on buffered mic samples (~200ms @ 48kHz). Bounds how far the mic track
+/// can drift if the capture clock runs ahead of the mixer cycle; past it the
+/// oldest mic audio is dropped. Mirrors `recorder::MAX_MIC_FIFO`.
+const MAX_MIC_FIFO: usize = 48_000 / 5;
+
 /// One output track: its WAV writer plus whether it has been written *this*
 /// cycle (so `end_cycle` knows which tracks to pad with silence).
 struct Track {
@@ -97,7 +102,11 @@ pub struct MultitrackRecorder {
     /// Cycles recorded so far = the shared length (in frames) of every track.
     cycles: u64,
     peers: HashMap<EndpointId, Track>,
-    mic: Track,
+    /// Your mic track. Fed asynchronously from the capture thread via
+    /// [`push_mic`](MultitrackRecorder::push_mic) into `mic_fifo`, then drained
+    /// one frame per `end_cycle` so it aligns with the cycle clock.
+    mic: WavWriter,
+    mic_fifo: VecDeque<i16>,
     /// Present in "Both" mode (stems + mixed), absent in "stems only".
     mix: Option<Track>,
 }
@@ -106,7 +115,7 @@ impl MultitrackRecorder {
     /// Create a recording in `dir` (which must already exist). `with_mix` adds
     /// the convenience mixed track (`mix.wav`). Your mic is always `me.wav`.
     pub fn create(dir: &Path, frame_samples: usize, with_mix: bool) -> io::Result<Self> {
-        let mic = Track::create(&dir.join("me.wav"))?;
+        let mic = WavWriter::new(&dir.join("me.wav"))?;
         let mix = if with_mix {
             Some(Track::create(&dir.join("mix.wav"))?)
         } else {
@@ -118,10 +127,16 @@ impl MultitrackRecorder {
             cycles: 0,
             peers: HashMap::new(),
             mic,
+            mic_fifo: VecDeque::new(),
             mix,
         })
     }
 
+    /// The session directory holding all the track files.
+    pub fn dir(&self) -> &Path {
+        &self.dir
+    }
+
     /// Register a peer's stem track, pre-padding it with silence back to cycle 0
     /// so it aligns with the others. Idempotent: a peer already tracked is left
     /// as-is (re-announce / name change doesn't restart their file).
@@ -146,10 +161,23 @@ impl MultitrackRecorder {
         self.peers.get_mut(&id).unwrap().write_frame(frame, fs)
     }
 
-    /// Record your mic frame for the current cycle.
+    /// Buffer a frame of your transmitted mic audio (called from the capture
-    pub fn write_mic(&mut self, frame: &[i16]) -> io::Result<()> {
+    /// thread, asynchronously to the mixer cycle). Bounded: oldest samples drop
-        let fs = self.frame_samples;
+    /// past [`MAX_MIC_FIFO`] so the mic track's offset can't grow without limit.
-        self.mic.write_frame(frame, fs)
+    pub fn push_mic(&mut self, frame: &[i16]) {
+        self.mic_fifo.extend(frame.iter().copied());
+        let overflow = self.mic_fifo.len().saturating_sub(MAX_MIC_FIFO);
+        if overflow > 0 {
+            self.mic_fifo.drain(..overflow);
+        }
+    }
+
+    /// Pull exactly `n` mic samples from the FIFO, silence-padded on underrun.
+    fn drain_mic(&mut self, n: usize) -> Vec<i16> {
+        let take = n.min(self.mic_fifo.len());
+        let mut v: Vec<i16> = self.mic_fifo.drain(..take).collect();
+        v.resize(n, 0);
+        v
     }
 
     /// Record the finished mixed-bus frame for the current cycle (no-op in
@@ -167,12 +195,12 @@ impl MultitrackRecorder {
     /// per mixer cycle, after the per-track writes.
     pub fn end_cycle(&mut self) -> io::Result<()> {
         let fs = self.frame_samples;
-        for track in self
+        // Mic: always one frame per cycle, drained from the FIFO (silence on
-            .peers
+        // underrun), so it tracks the cycle clock like the peer stems.
-            .values_mut()
+        let mic_frame = self.drain_mic(fs);
-            .chain(std::iter::once(&mut self.mic))
+        self.mic.write_samples(&mic_frame)?;
-            .chain(self.mix.as_mut())
+        // Peers + the optional mix track: pad any not written this cycle.
-        {
+        for track in self.peers.values_mut().chain(self.mix.as_mut()) {
             if !track.written_this_cycle {
                 track.write_silence(fs)?;
             }
@@ -184,7 +212,7 @@ impl MultitrackRecorder {
 
     /// Finalize every track's WAV header. Consumes the recorder.
     pub fn finalize(self) -> io::Result<()> {
-        self.mic.writer.finalize()?;
+        self.mic.finalize()?;
         if let Some(mix) = self.mix {
             mix.writer.finalize()?;
         }
@@ -245,14 +273,14 @@ mod tests {
         rec.add_peer(p1, "p1").unwrap();
         rec.add_peer(p2, "p2").unwrap();
 
-        // 3 cycles; p1 talks every cycle, p2 only on cycle 2, mic talks twice.
+        // 3 cycles; p1 talks every cycle, p2 only on cycle 2, mic pushed twice.
         for c in 0..3 {
             rec.write_peer(p1, &[1, 1, 1, 1]).unwrap();
             if c == 2 {
                 rec.write_peer(p2, &[2, 2, 2, 2]).unwrap();
             }
             if c < 2 {
-                rec.write_mic(&[9, 9, 9, 9]).unwrap();
+                rec.push_mic(&[9, 9, 9, 9]);
             }
             rec.write_mix(&[5, 5, 5, 5]).unwrap();
             rec.end_cycle().unwrap();

src/config.rs

@@ -44,6 +44,41 @@ impl RoomLayout {
         [RoomLayout::ThreeColumn, RoomLayout::BottomDock, RoomLayout::Drawer];
 }
 
+/// What a call recording captures. `Mixed` is the original single-file behaviour;
+/// `Multitrack`/`Both` write per-peer stems for post-production (see
+/// `docs/multitrack-recording-plan.md`).
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
+pub enum RecordingMode {
+    /// One mixed WAV (your mic + the incoming mix). Smallest; the default.
+    #[default]
+    Mixed,
+    /// One WAV per peer + your mic, all sample-aligned. Rebuild the mix yourself.
+    Multitrack,
+    /// Per-peer stems + your mic + a convenience mixed track.
+    Both,
+}
+
+impl RecordingMode {
+    /// All variants, in picker display order.
+    pub const ALL: [RecordingMode; 3] =
+        [RecordingMode::Mixed, RecordingMode::Multitrack, RecordingMode::Both];
+
+    /// True when this mode writes per-peer stem tracks (Multitrack or Both).
+    pub fn is_multitrack(self) -> bool {
+        matches!(self, RecordingMode::Multitrack | RecordingMode::Both)
+    }
+}
+
+impl std::fmt::Display for RecordingMode {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(match self {
+            RecordingMode::Mixed => "Mixed (single file)",
+            RecordingMode::Multitrack => "Multitrack (per-peer stems)",
+            RecordingMode::Both => "Both (stems + mixed)",
+        })
+    }
+}
+
 impl std::fmt::Display for RoomLayout {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         f.write_str(match self {
@@ -141,6 +176,9 @@ pub struct AppConfig {
     /// Chosen UI colour theme.
     #[serde(default)]
     pub theme: AppTheme,
+    /// What a call recording captures (mixed / per-peer stems / both).
+    #[serde(default)]
+    pub recording_mode: RecordingMode,
     #[serde(default)]
     pub custom_sound_self_join: Option<String>,
     #[serde(default)]
@@ -195,6 +233,7 @@ impl Default for AppConfig {
             chat_drawer_width: default_chat_drawer_width(),
             room_layout: RoomLayout::default(),
             theme: AppTheme::default(),
+            recording_mode: RecordingMode::default(),
             custom_sound_self_join: None,
             custom_sound_peer_join: None,
             custom_sound_peer_leave: None,

src/core/messages.rs

@@ -1,4 +1,4 @@
-use crate::config::NetworkMode;
+use crate::config::{NetworkMode, RecordingMode};
 use crate::network::PeerState;
 use iroh::EndpointId;
 
@@ -29,6 +29,9 @@ pub enum CoreCommand {
     /// 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),
+    /// Set what a recording captures (mixed / per-peer stems / both). Takes
+    /// effect on the next recording start. Sent at startup from config.
+    SetRecordingMode(RecordingMode),
     /// Broadcast a room text-chat message. No-op when not in a call.
     SendChat(String),
     /// Set the pixelpass binary location (config override, empty = use `$PATH`).

src/core/mod.rs

@@ -11,7 +11,8 @@ use crate::network::{
 };
 use crate::core::messages::{CoreCommand, UiEvent};
 
-use crate::config::NetworkMode;
+use crate::config::{NetworkMode, RecordingMode};
+use crate::audio::multitrack::MultitrackRecorder;
 use iroh::{Endpoint, EndpointId, RelayMode, endpoint::presets, protocol::Router};
 use iroh_gossip::net::Gossip;
 use tokio::sync::{mpsc, Mutex};
@@ -379,9 +380,15 @@ impl ActiveSession {
 async fn stop_recording(
     recorder: &Arc<std::sync::Mutex<Option<crate::audio::recorder::Recorder>>>,
     is_recording: &Arc<AtomicBool>,
+    multitrack: &Arc<std::sync::Mutex<Option<MultitrackRecorder>>>,
+    is_multitrack: &Arc<AtomicBool>,
     ui_tx: &mpsc::Sender<UiEvent>,
 ) {
     is_recording.store(false, Ordering::Relaxed);
+    is_multitrack.store(false, Ordering::Relaxed);
+    // Exactly one slot is ever active for a given recording, but finalize both
+    // defensively. The reported path is the file (mixed) or the session dir
+    // (multitrack).
     let rec = recorder.lock().unwrap().take();
     if let Some(rec) = rec {
         let path = rec.path().to_string_lossy().to_string();
@@ -391,6 +398,15 @@ async fn stop_recording(
         crate::log_msg(&format!("Recording saved: {path}"));
         let _ = ui_tx.send(UiEvent::RecordingStopped { path }).await;
     }
+    let mt = multitrack.lock().unwrap().take();
+    if let Some(mt) = mt {
+        let path = mt.dir().to_string_lossy().to_string();
+        if let Err(e) = mt.finalize() {
+            crate::log_msg(&format!("Failed to finalize multitrack recording: {e}"));
+        }
+        crate::log_msg(&format!("Multitrack recording saved: {path}/"));
+        let _ = ui_tx.send(UiEvent::RecordingStopped { path }).await;
+    }
 }
 
 async fn run_core_loop(
@@ -417,6 +433,14 @@ async fn run_core_loop(
     let recorder: Arc<std::sync::Mutex<Option<crate::audio::recorder::Recorder>>> =
         Arc::new(std::sync::Mutex::new(None));
     let is_recording = Arc::new(AtomicBool::new(false));
+    // Multitrack (stem) recording: a parallel recorder used instead of the mixed
+    // `recorder` when `recording_mode` is Multitrack/Both. Exactly one of the two
+    // slots is ever active. `is_multitrack` is the fast-path gate the audio loops
+    // read (cheap) to decide whether to tap raw per-peer stems this cycle.
+    let multitrack: Arc<std::sync::Mutex<Option<MultitrackRecorder>>> =
+        Arc::new(std::sync::Mutex::new(None));
+    let is_multitrack = Arc::new(AtomicBool::new(false));
+    let mut recording_mode = RecordingMode::default();
     let peer_volumes = Arc::new(Mutex::new(HashMap::<EndpointId, f32>::new()));
     // Peers locally muted by us: decoded for level metering but not mixed.
     let locally_muted = Arc::new(Mutex::new(HashSet::<EndpointId>::new()));
@@ -438,7 +462,7 @@ async fn run_core_loop(
 
                 // Finalize any recording before tearing down the old session — its
                 // capture/mixer feeders are about to stop.
-                stop_recording(&recorder, &is_recording, &ui_tx).await;
+                stop_recording(&recorder, &is_recording, &multitrack, &is_multitrack, &ui_tx).await;
 
                 // Clean up any existing session
                 if let Some(session) = active_session.take() {
@@ -608,6 +632,8 @@ async fn run_core_loop(
                 let ui_tx_capture = ui_tx.clone();
                 let recorder_capture = recorder.clone();
                 let is_recording_capture = is_recording.clone();
+                let multitrack_capture = multitrack.clone();
+                let is_multitrack_capture = is_multitrack.clone();
 
                 let capture_thread = std::thread::spawn(move || {
                     use opus::{Channels, Application};
@@ -657,10 +683,14 @@ async fn run_core_loop(
                         // Record what we transmit (post-gain, post-gate, post-mute):
                         // this is exactly the mic audio peers receive from us. The
                         // mixer task pairs it with the incoming mix.
-                        if is_recording_capture.load(Ordering::Relaxed)
+                        if is_recording_capture.load(Ordering::Relaxed) {
-                            && let Some(rec) = recorder_capture.lock().unwrap().as_mut()
+                            if is_multitrack_capture.load(Ordering::Relaxed) {
-                        {
+                                if let Some(mt) = multitrack_capture.lock().unwrap().as_mut() {
-                            rec.push_mic(&pcm);
+                                    mt.push_mic(&pcm);
+                                }
+                            } else if let Some(rec) = recorder_capture.lock().unwrap().as_mut() {
+                                rec.push_mic(&pcm);
+                            }
                         }
 
                         if let Ok(encoded) = encoder.encode(&pcm) {
@@ -729,6 +759,8 @@ async fn run_core_loop(
                 let ring_fill_mixer = ring_fill.clone();
                 let recorder_mixer = recorder.clone();
                 let is_recording_mixer = is_recording.clone();
+                let multitrack_mixer = multitrack.clone();
+                let is_multitrack_mixer = is_multitrack.clone();
                 let mixer_task = tokio::spawn(async move {
                     // Mix-bus soft limiter: rides loud multi-peer moments down to
                     // the ceiling instead of hard-clipping. State carries across
@@ -760,6 +792,13 @@ async fn run_core_loop(
                         let muted_peers = locally_muted_mixer.lock().await.clone();
                         let mut peer_frames = Vec::new();
 
+                        // Multitrack stem capture: tap each peer's RAW decoded frame
+                        // (pre-volume, pre-mute, pre-limiter) so the stems are clean
+                        // source. Only collected while a multitrack recording is live.
+                        let mt_active = is_recording_mixer.load(Ordering::Relaxed)
+                            && is_multitrack_mixer.load(Ordering::Relaxed);
+                        let mut stems: Vec<(EndpointId, Vec<i16>)> = Vec::new();
+
                         {
                             let mut guard = jitter_mixer.lock().await;
                             for (&peer_id, buffer) in guard.iter_mut() {
@@ -770,6 +809,10 @@ async fn run_core_loop(
                                     continue;
                                 };
 
+                                if mt_active {
+                                    stems.push((peer_id, frame.clone()));
+                                }
+
                                 let vol = current_volumes.get(&peer_id).copied().unwrap_or(1.0);
                                 apply_volume(&mut frame, vol);
 
@@ -795,10 +838,25 @@ async fn run_core_loop(
                         let out_gain = f32::from_bits(output_gain_mixer.load(Ordering::Relaxed));
                         let mixed = limiter.process(&mixed_sum, out_gain);
 
-                        // Record the true call audio (incoming mix + our mic),
+                        // Record the true call audio, independent of local deafen —
-                        // independent of local deafen — deafen only silences our
+                        // deafen only silences our own monitor, not what the call
-                        // own monitor, not what the call actually carried.
+                        // carried. Multitrack writes raw per-peer stems (+ the mixed
-                        if is_recording_mixer.load(Ordering::Relaxed)
+                        // track in Both mode) one aligned frame per cycle; Mixed mode
+                        // writes the single blended file as before.
+                        if mt_active {
+                            if let Some(mt) = multitrack_mixer.lock().unwrap().as_mut() {
+                                let res = (|| -> std::io::Result<()> {
+                                    for (id, f) in &stems {
+                                        mt.write_peer(*id, f)?;
+                                    }
+                                    mt.write_mix(&mixed)?;
+                                    mt.end_cycle()
+                                })();
+                                if let Err(e) = res {
+                                    crate::log_msg(&format!("Multitrack write failed: {e}"));
+                                }
+                            }
+                        } else if is_recording_mixer.load(Ordering::Relaxed)
                             && let Some(rec) = recorder_mixer.lock().unwrap().as_mut()
                             && let Err(e) = rec.write_frame(&mixed)
                         {
@@ -840,6 +898,8 @@ async fn run_core_loop(
                 let grace_timers_events = grace_timers.clone();
                 let seen_connected: SeenConnected = Arc::new(std::sync::Mutex::new(HashSet::new()));
                 let seen_connected_events = seen_connected.clone();
+                let multitrack_events = multitrack.clone();
+                let is_multitrack_events = is_multitrack.clone();
                 let event_task = tokio::spawn(async move {
                     while let Some(event) = room_events.recv().await {
                         match event {
@@ -852,6 +912,14 @@ async fn run_core_loop(
                                 // Hand over the full address so reconnects can dial
                                 // it directly rather than via the gossip lookup.
                                 transport_events.connect_peer(state.addr.clone()).await;
+                                // If a multitrack recording is live, give this peer
+                                // its own stem track (silence-padded back to t=0).
+                                if is_multitrack_events.load(Ordering::Relaxed)
+                                    && let Some(mt) = multitrack_events.lock().unwrap().as_mut()
+                                    && let Err(e) = mt.add_peer(peer_id, &state.name)
+                                {
+                                    crate::log_msg(&format!("multitrack add_peer (join) failed: {e}"));
+                                }
                                 let _ = ui_tx_events.send(UiEvent::PeerJoined { id: peer_id, state }).await;
                             }
                             RoomEvent::PeerLeft(peer_id) => {
@@ -944,7 +1012,7 @@ async fn run_core_loop(
 
             CoreCommand::Leave => {
                 // Finalize any recording first, while the audio feeders are alive.
-                stop_recording(&recorder, &is_recording, &ui_tx).await;
+                stop_recording(&recorder, &is_recording, &multitrack, &is_multitrack, &ui_tx).await;
                 current_sharing = None;
                 if let Some(session) = active_session.take() {
                     session.shutdown(audio_backend.clone()).await;
@@ -1039,6 +1107,10 @@ async fn run_core_loop(
                 network_mode = mode;
             }
 
+            CoreCommand::SetRecordingMode(mode) => {
+                recording_mode = mode;
+            }
+
             CoreCommand::SetRecording(enabled) => {
                 if enabled {
                     // Only record while in a call, and not already recording.
@@ -1049,23 +1121,58 @@ async fn run_core_loop(
                     } else if !is_recording.load(Ordering::Relaxed) {
                         match dirs::home_dir() {
                             Some(home) => {
-                                let dir = home.join("peerspeak-recordings");
+                                let base = home.join("peerspeak-recordings");
                                 let now = std::time::SystemTime::now()
                                     .duration_since(std::time::UNIX_EPOCH)
                                     .map(|d| d.as_secs())
                                     .unwrap_or(0);
-                                let started = std::fs::create_dir_all(&dir)
+                                let result: Result<String, String> = if recording_mode.is_multitrack() {
-                                    .map_err(|e| e.to_string())
+                                    // Multitrack/Both: a per-session directory of stems.
-                                    .and_then(|_| {
+                                    let stamp = crate::audio::recorder::timestamp_filename(now);
-                                        crate::audio::recorder::Recorder::create(&dir, now)
+                                    let session_dir = base.join(stamp.trim_end_matches(".wav"));
+                                    std::fs::create_dir_all(&session_dir)
+                                        .map_err(|e| e.to_string())
+                                        .and_then(|_| {
+                                            MultitrackRecorder::create(
+                                                &session_dir,
+                                                FRAME_SAMPLES,
+                                                matches!(recording_mode, RecordingMode::Both),
+                                            )
                                             .map_err(|e| e.to_string())
-                                    });
+                                        })
-                                match started {
+                                        .map(|mut mt| {
-                                    Ok(rec) => {
+                                            // Register everyone already in the room so their
-                                        let path = rec.path().to_string_lossy().to_string();
+                                            // stems are silence-aligned from t=0.
-                                        *recorder.lock().unwrap() = Some(rec);
+                                            if let Some(session) = &active_session {
+                                                for (id, st) in session.room_state.active_peers() {
+                                                    if let Err(e) = mt.add_peer(id, &st.name) {
+                                                        crate::log_msg(&format!("multitrack add_peer failed: {e}"));
+                                                    }
+                                                }
+                                            }
+                                            let path = mt.dir().to_string_lossy().to_string();
+                                            *multitrack.lock().unwrap() = Some(mt);
+                                            is_multitrack.store(true, Ordering::Relaxed);
+                                            path
+                                        })
+                                } else {
+                                    // Mixed: one file (original behaviour).
+                                    std::fs::create_dir_all(&base)
+                                        .map_err(|e| e.to_string())
+                                        .and_then(|_| {
+                                            crate::audio::recorder::Recorder::create(&base, now)
+                                                .map_err(|e| e.to_string())
+                                        })
+                                        .map(|rec| {
+                                            let path = rec.path().to_string_lossy().to_string();
+                                            *recorder.lock().unwrap() = Some(rec);
+                                            path
+                                        })
+                                };
+                                match result {
+                                    Ok(path) => {
                                         is_recording.store(true, Ordering::Relaxed);
-                                        crate::log_msg(&format!("Recording started: {path}"));
+                                        crate::log_msg(&format!("Recording started ({recording_mode:?}): {path}"));
                                         let _ = ui_tx
                                             .send(UiEvent::RecordingStarted { path })
                                             .await;
@@ -1085,7 +1192,7 @@ async fn run_core_loop(
                         }
                     }
                 } else {
-                    stop_recording(&recorder, &is_recording, &ui_tx).await;
+                    stop_recording(&recorder, &is_recording, &multitrack, &is_multitrack, &ui_tx).await;
                 }
             }