fix(pipewire): only auto-reroute default devices

CHANGELOG.md

@@ -18,6 +18,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Timestamps now stay monotonic across device and graph changes.
 - **ALSA**: A nonzero but sub-millisecond stream timeout is no longer treated as a non-blocking poll.
+- **PipeWire**: Streams for a specific device no longer auto-reroute if it disappears.
 - **visionOS**: The CoreAudio backend now builds.
 - **WASAPI**: Reported buffer sizes are no longer off by one frame.
 - **WASAPI**: `Stream::drop`, `play`, and `pause` no longer panic when the device is lost.

src/error.rs

@@ -14,6 +14,12 @@ pub enum ErrorKind {
 
     /// The active audio route changed and the stream was automatically rerouted.
     /// The stream remains active and no rebuild is required.
+    ///
+    /// Only fires for a stream built from the default device, on backends that support following
+    /// it. A stream built from a specific device does not follow a replacement; if that device
+    /// disappears, it reports [`DeviceNotAvailable`] instead.
+    ///
+    /// [`DeviceNotAvailable`]: ErrorKind::DeviceNotAvailable
     DeviceChanged,
 
     /// The requested audio device is not available.

src/host/pipewire/device.rs

@@ -399,6 +399,10 @@ impl DeviceTrait for Device {
                         last_quantum: last_quantum_clone,
                         start,
                         connect_automatically: device.connect_automatically.load(Ordering::Relaxed),
+                        is_default_device: matches!(
+                            device.class(),
+                            Class::DefaultSink | Class::DefaultInput | Class::DefaultOutput
+                        ),
                     },
                     data_callback,
                     error_callback,
@@ -423,7 +427,6 @@ impl DeviceTrait for Device {
                     error_callback,
                     pending_device_changed,
                     invalidated,
-                    is_default_device,
                 } = stream_data;
 
                 let default_monitor = if let Some(key) = device.default_metadata_key() {
@@ -446,7 +449,6 @@ impl DeviceTrait for Device {
                 } else {
                     None
                 };
-                is_default_device.store(default_monitor.is_some(), Ordering::Relaxed);
                 let stream_clone = stream.clone();
                 let mainloop_rc1 = mainloop.clone();
                 let error_callback_cmd = error_callback.clone();
@@ -575,6 +577,10 @@ impl DeviceTrait for Device {
                         last_quantum: last_quantum_clone,
                         start,
                         connect_automatically: device.connect_automatically.load(Ordering::Relaxed),
+                        is_default_device: matches!(
+                            device.class(),
+                            Class::DefaultSink | Class::DefaultInput | Class::DefaultOutput
+                        ),
                     },
                     data_callback,
                     error_callback,
@@ -599,7 +605,6 @@ impl DeviceTrait for Device {
                     error_callback,
                     pending_device_changed,
                     invalidated,
-                    is_default_device,
                 } = stream_data;
 
                 let default_monitor = if let Some(key) = device.default_metadata_key() {
@@ -622,7 +627,6 @@ impl DeviceTrait for Device {
                 } else {
                     None
                 };
-                is_default_device.store(default_monitor.is_some(), Ordering::Relaxed);
                 let stream_clone = stream.clone();
                 let mainloop_rc1 = mainloop.clone();
                 let error_callback_cmd = error_callback.clone();

src/host/pipewire/stream.rs

@@ -225,7 +225,7 @@ pub struct UserData<D> {
     format: AudioInfoRaw,
     last_quantum: Arc<AtomicU64>,
     start: Instant,
-    is_default_device: Arc<AtomicBool>,
+    is_default_device: bool,
     has_connected: bool,
     invalidated: Arc<AtomicBool>,
     pending_device_changed: Arc<AtomicBool>,
@@ -253,7 +253,7 @@ impl<D> UserData<D> {
             StreamState::Unconnected => {
                 // Let the metadata monitor fire for default-device streams
                 if self.has_connected
-                    && !self.is_default_device.load(Ordering::Relaxed)
+                    && !self.is_default_device
                     && !self.invalidated.swap(true, Ordering::Relaxed)
                 {
                     emit_error(
@@ -376,7 +376,6 @@ pub struct StreamData<D> {
     pub error_callback: ErrorCallbackArc,
     pub pending_device_changed: Arc<AtomicBool>,
     pub invalidated: Arc<AtomicBool>,
-    pub is_default_device: Arc<AtomicBool>,
 }
 
 /// Fallback timestamp using elapsed time since stream creation.
@@ -525,6 +524,7 @@ pub struct ConnectParams {
     pub last_quantum: Arc<AtomicU64>,
     pub start: Instant,
     pub connect_automatically: bool,
+    pub is_default_device: bool,
 }
 
 pub fn connect_output<D, E>(
@@ -543,6 +543,7 @@ where
         last_quantum,
         start,
         connect_automatically,
+        is_default_device,
     } = params;
 
     let mainloop = MainLoopRc::new(None)?;
@@ -553,7 +554,6 @@ where
     let invalidated = Arc::new(AtomicBool::new(false));
 
     let pending_device_changed = Arc::new(AtomicBool::new(false));
-    let is_default_device = Arc::new(AtomicBool::new(false));
 
     let core_monitor = {
         let invalidated_core = invalidated.clone();
@@ -582,7 +582,7 @@ where
         last_quantum,
         start,
         invalidated: invalidated.clone(),
-        is_default_device: is_default_device.clone(),
+        is_default_device,
         has_connected: false,
         pending_device_changed: pending_device_changed.clone(),
         #[cfg(feature = "realtime")]
@@ -756,6 +756,9 @@ where
     if connect_automatically {
         flags |= StreamFlags::AUTOCONNECT;
     }
+    if !is_default_device {
+        flags |= StreamFlags::DONT_RECONNECT;
+    }
 
     stream.connect(Direction::Output, None, flags, &mut params)?;
 
@@ -769,7 +772,6 @@ where
         error_callback: error_callback_out,
         pending_device_changed,
         invalidated,
-        is_default_device,
     })
 }
 
@@ -789,6 +791,7 @@ where
         last_quantum,
         start,
         connect_automatically,
+        is_default_device,
     } = params;
 
     let mainloop = MainLoopRc::new(None)?;
@@ -799,7 +802,6 @@ where
     let invalidated = Arc::new(AtomicBool::new(false));
 
     let pending_device_changed = Arc::new(AtomicBool::new(false));
-    let is_default_device = Arc::new(AtomicBool::new(false));
 
     let core_monitor = {
         let invalidated_core = invalidated.clone();
@@ -828,7 +830,7 @@ where
         last_quantum,
         start,
         invalidated: invalidated.clone(),
-        is_default_device: is_default_device.clone(),
+        is_default_device,
         has_connected: false,
         pending_device_changed: pending_device_changed.clone(),
         #[cfg(feature = "realtime")]
@@ -985,6 +987,9 @@ where
     if connect_automatically {
         flags |= StreamFlags::AUTOCONNECT;
     }
+    if !is_default_device {
+        flags |= StreamFlags::DONT_RECONNECT;
+    }
 
     stream.connect(Direction::Input, None, flags, &mut params)?;
 
@@ -998,6 +1003,5 @@ where
         error_callback: error_callback_out,
         pending_device_changed,
         invalidated,
-        is_default_device,
     })
 }

src/traits.rs

@@ -73,11 +73,27 @@ pub trait HostTrait {
     /// The default input audio device on the system.
     ///
     /// Returns `None` if no input device is available.
+    ///
+    /// Some backends reroute a stream built from this device to the new default device when it
+    /// changes; capture continues there, and [`ErrorKind::DeviceChanged`] is reported. Other
+    /// backends report [`ErrorKind::DeviceNotAvailable`] instead, and the caller must rebuild the
+    /// stream.
+    ///
+    /// [`ErrorKind::DeviceChanged`]: crate::ErrorKind::DeviceChanged
+    /// [`ErrorKind::DeviceNotAvailable`]: crate::ErrorKind::DeviceNotAvailable
     fn default_input_device(&self) -> Option<Self::Device>;
 
     /// The default output audio device on the system.
     ///
     /// Returns `None` if no output device is available.
+    ///
+    /// Some backends reroute a stream built from this device to the new default device when it
+    /// changes; playback continues there, and [`ErrorKind::DeviceChanged`] is reported. Other
+    /// backends report [`ErrorKind::DeviceNotAvailable`] instead, and the caller must rebuild the
+    /// stream.
+    ///
+    /// [`ErrorKind::DeviceChanged`]: crate::ErrorKind::DeviceChanged
+    /// [`ErrorKind::DeviceNotAvailable`]: crate::ErrorKind::DeviceNotAvailable
     fn default_output_device(&self) -> Option<Self::Device>;
 
     /// An iterator yielding all `Device`s currently available to the system that support one or more