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Revert fix(wasapi): do not emit DeviceChanged when not rerouted #1350

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Revert fix(wasapi): do not emit DeviceChanged when not rerouted #1350

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5136c13
Revert "fix(wasapi): do not emit DeviceChanged when not rerouted"
LastExceed Sep 1, 2026
5ea9473
add to changelog
LastExceed Sep 1, 2026
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2 changes: 2 additions & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
- **AudioWorklet**: Fix stale output when the data callback grows Wasm memory.
- **JACK**: Channel enumeration is capped at the physical system port count again.
- **WASAPI**: Device enumeration no longer panics if the COM enumerator fails to initialize.
- **WASAPI**: Revert "Default device changes no longer report `DeviceChanged`" as it was misinformed.

@roderickvd roderickvd Sep 1, 2026

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I think this should be a bit more succinct: just document observable behavior, no need to pony up about being wrong or right.

Default device streams **do** reroute automatically.

## [0.18.2] - 2026-08-16

Expand Down
32 changes: 9 additions & 23 deletions src/host/wasapi/stream.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -38,12 +38,12 @@ fn get_current_default(flow: Audio::EDataFlow) -> Option<Audio::IMMDevice> {
super::device::current_default_endpoint(flow)
}

/// Fires a Windows auto-reset event when the system default audio device changes.
/// Fires a Windows auto-reset event when the system default audio device changes, allowing
/// the stream run loop to deliver `ErrorKind::DeviceChanged` to the caller.
pub(crate) struct DefaultDeviceMonitor {
enumerator: Audio::IMMDeviceEnumerator,
client: Audio::IMMNotificationClient,
event: Foundation::HANDLE,
pub(crate) flow: Audio::EDataFlow,
pub(crate) pending_device_changed: Arc<AtomicBool>,
}

Expand Down Expand Up @@ -79,7 +79,6 @@ impl DefaultDeviceMonitor {
enumerator,
client,
event,
flow,
pending_device_changed,
})
}
Expand Down Expand Up @@ -211,8 +210,9 @@ pub struct Stream {
// QueryPerformanceFrequency result, cached at construction (constant for the system lifetime).
qpc_frequency: u64,

// Present for default-device streams. Dropped after the run thread joins, ensuring the
// HANDLE is not waited on when it is closed.
// Present for default-device streams; fires `ErrorKind::DeviceChanged` when the system
// default changes. Dropped after the run thread joins, ensuring the HANDLE is not
// waited on when it is closed.
_default_device_monitor: Option<DefaultDeviceMonitor>,

// Latch that ensures no callbacks fire before the caller receives the `Stream` handle.
Expand Down Expand Up @@ -252,12 +252,10 @@ struct RunContext {

commands: Receiver<Command>,

// Set by a device-change notification callback when SetEvent fails.
// Set by a device-change notification callback when SetEvent fails. The audio loop delivers
// DeviceChanged on its next iteration.
pending_device_changed: Option<Arc<AtomicBool>>,

// Set when this stream tracks the default device, rather than a pinned one.
default_device_flow: Option<Audio::EDataFlow>,

// Owned here so the worker thread closes it on exit in a self-join case.
pending_scheduled_event: Foundation::HANDLE,
}
Expand Down Expand Up @@ -342,13 +340,11 @@ impl Stream {
let pending_device_changed = default_device_monitor
.as_ref()
.map(|m| m.pending_device_changed.clone());
let default_device_flow = default_device_monitor.as_ref().map(|m| m.flow);
let run_context = RunContext {
handles,
stream: stream_inner,
commands: rx,
pending_device_changed,
default_device_flow,
pending_scheduled_event,
};

Expand Down Expand Up @@ -414,13 +410,11 @@ impl Stream {
let pending_device_changed = default_device_monitor
.as_ref()
.map(|m| m.pending_device_changed.clone());
let default_device_flow = default_device_monitor.as_ref().map(|m| m.flow);
let run_context = RunContext {
handles,
stream: stream_inner,
commands: rx,
pending_device_changed,
default_device_flow,
pending_scheduled_event,
};

Expand Down Expand Up @@ -727,14 +721,6 @@ fn boost_current_thread_priority(
}
}

// WASAPI never rebinds the IAudioClient, so report what's actually true instead of DeviceChanged.
fn default_device_change_error(flow: Option<Audio::EDataFlow>) -> Error {
match flow.and_then(get_current_default) {
None => ErrorKind::DeviceNotAvailable.into(),
Some(_) => ErrorKind::StreamInvalidated.into(),
}
}

fn process_commands_and_await_signal(
run_context: &mut RunContext,
error_callback: &ErrorCallbackArc,
Expand All @@ -753,7 +739,7 @@ fn process_commands_and_await_signal(
if flag.swap(false, Ordering::Relaxed) {
emit_error(
error_callback,
default_device_change_error(run_context.default_device_flow),
Error::with_message(ErrorKind::DeviceChanged, "Default audio device changed"),

@roderickvd roderickvd Sep 1, 2026

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This seems to throw out more than #1339 needs. StreamInvalidated is wrong when a replacement device exists, but default_device_change_error's other branch serves a different purpose:

OnDeviceStateChanged and OnDeviceRemoved only SetEvent when get_current_default(self.flow).is_none() (see the comment above them), so they only ever wake this code up for the no-replacement case. After this revert that case gets reported as DeviceChanged too, which contradicts its definition: "the stream remains active and no rebuild is required." There's nothing to route to there, so that isn't true.

I think the fix should be smaller than a full revert: keep default_device_change_error, just fix the one arm that was actually wrong:

fn default_device_change_error(flow: Option<Audio::EDataFlow>) -> Error {
    match flow.and_then(get_current_default) {
        None => ErrorKind::DeviceNotAvailable.into(),
        Some(_) => ErrorKind::DeviceChanged.into(), // was StreamInvalidated
    }
}

);
}
}
Expand All @@ -774,7 +760,7 @@ fn process_commands_and_await_signal(
if handle_idx >= 2 {
emit_error(
error_callback,
default_device_change_error(run_context.default_device_flow),
Error::with_message(ErrorKind::DeviceChanged, "Default audio device changed"),
);
return ControlFlow::Continue(false);
}
Expand Down