feat(wasapi): enable resampling when necessary (RustAudio#1097)

This allows non-native sample rates to be resampled by the WASAPI server.

(cherry picked from commit 6627959)

Author: yeah-its-gloria

CHANGELOG.md

@@ -1,3 +1,7 @@
+# Unreleased
+
+- Backport: **WASAPI**: Allow non-native sample rates to be used via as-necessary resampling in the WASAPI server process.
+
 # Version 0.14.1 (2022-10-23)
 
 - Support the 0.6.1 release of `alsa-rs`

src/host/wasapi/device.rs

@@ -22,7 +22,6 @@ use std::ffi::c_void;
 use windows::core::Interface;
 use windows::core::GUID;
 use windows::Win32::Devices::Properties;
-use windows::Win32::Foundation;
 use windows::Win32::Media::Audio::IAudioRenderClient;
 use windows::Win32::Media::{Audio, KernelStreaming, Multimedia};
 use windows::Win32::System::Com;
@@ -36,6 +35,10 @@ use crate::{traits::DeviceTrait, BuildStreamError, StreamError};
 pub type SupportedInputConfigs = std::vec::IntoIter<SupportedStreamConfigRange>;
 pub type SupportedOutputConfigs = std::vec::IntoIter<SupportedStreamConfigRange>;
 
+const DEFAULT_FLAGS: u32 = Audio::AUDCLNT_STREAMFLAGS_EVENTCALLBACK
+    | Audio::AUDCLNT_STREAMFLAGS_SRC_DEFAULT_QUALITY
+    | Audio::AUDCLNT_STREAMFLAGS_AUTOCONVERTPCM;
+
 /// Wrapper because of that stupid decision to remove `Send` and `Sync` from raw pointers.
 #[derive(Clone)]
 struct IAudioClientWrapper(Audio::IAudioClient);
@@ -195,48 +198,12 @@ unsafe fn data_flow_from_immendpoint(endpoint: &Audio::IMMEndpoint) -> Audio::ED
 
 // Given the audio client and format, returns whether or not the format is supported.
 pub unsafe fn is_format_supported(
-    client: &Audio::IAudioClient,
-    waveformatex_ptr: *const Audio::WAVEFORMATEX,
+    _client: &Audio::IAudioClient,
+    _waveformatex_ptr: *const Audio::WAVEFORMATEX,
 ) -> Result<bool, SupportedStreamConfigsError> {
-    // Check if the given format is supported.
-    let is_supported = |waveformatex_ptr, mut closest_waveformatex_ptr| {
-        let result = client.IsFormatSupported(
-            Audio::AUDCLNT_SHAREMODE_SHARED,
-            waveformatex_ptr,
-            &mut closest_waveformatex_ptr,
-        );
-        // `IsFormatSupported` can return `S_FALSE` (which means that a compatible format
-        // has been found, but not an exact match) so we also treat this as unsupported.
-        match result {
-            Audio::AUDCLNT_E_DEVICE_INVALIDATED => {
-                Err(SupportedStreamConfigsError::DeviceNotAvailable)
-            }
-            r if r.is_err() => Ok(false),
-            Foundation::S_FALSE => Ok(false),
-            _ => Ok(true),
-        }
-    };
-
-    // First we want to retrieve a pointer to the `WAVEFORMATEX`.
-    // Although `GetMixFormat` writes the format to a given `WAVEFORMATEX` pointer,
-    // the pointer itself may actually point to a `WAVEFORMATEXTENSIBLE` structure.
-    // We check the wFormatTag to determine this and get a pointer to the correct type.
-    match (*waveformatex_ptr).wFormatTag as u32 {
-        Audio::WAVE_FORMAT_PCM | Multimedia::WAVE_FORMAT_IEEE_FLOAT => {
-            let mut closest_waveformatex = *waveformatex_ptr;
-            let closest_waveformatex_ptr = &mut closest_waveformatex as *mut _;
-            is_supported(waveformatex_ptr, closest_waveformatex_ptr)
-        }
-        KernelStreaming::WAVE_FORMAT_EXTENSIBLE => {
-            let waveformatextensible_ptr = waveformatex_ptr as *const Audio::WAVEFORMATEXTENSIBLE;
-            let mut closest_waveformatextensible = *waveformatextensible_ptr;
-            let closest_waveformatextensible_ptr = &mut closest_waveformatextensible as *mut _;
-            let closest_waveformatex_ptr =
-                closest_waveformatextensible_ptr as *mut Audio::WAVEFORMATEX;
-            is_supported(waveformatex_ptr, closest_waveformatex_ptr)
-        }
-        _ => Ok(false),
-    }
+    // Checking formats is not needed for shared mode with auto-conversion, therefore this check has been removed until someone implements WASAPI exclusive mode support
+    // I used an NAudio issue as reference: https://github.com/naudio/NAudio/issues/819
+    Ok(true)
 }
 
 // Get a cpal Format from a WAVEFORMATEX.
@@ -622,7 +589,7 @@ impl Device {
             let buffer_duration =
                 buffer_size_to_duration(&config.buffer_size, config.sample_rate.0);
 
-            let mut stream_flags = Audio::AUDCLNT_STREAMFLAGS_EVENTCALLBACK;
+            let mut stream_flags = DEFAULT_FLAGS;
 
             if self.data_flow() == Audio::eRender {
                 stream_flags |= Audio::AUDCLNT_STREAMFLAGS_LOOPBACK;
@@ -758,7 +725,7 @@ impl Device {
                 audio_client
                     .Initialize(
                         share_mode,
-                        Audio::AUDCLNT_STREAMFLAGS_EVENTCALLBACK,
+                        DEFAULT_FLAGS,
                         buffer_duration,
                         0,
                         &format_attempt.Format,