Implement buffer_size_range for pipewire, alsa, and wasapi & update

example

Author: jacksongoode

examples/set_buffer_size.rs

@@ -1,47 +1,86 @@
-//! This example demonstrates how to request a specific buffer size from the CoreAudio backend.
-//! Probably only works on macOS.
+//! This example demonstrates how to request a specific buffer size from the audio backends.
+
+use interflow::channel_map::{ChannelMap32, CreateBitset};
+use interflow::prelude::*;
+use std::sync::{
+    atomic::{AtomicBool, Ordering},
+    Arc,
+};
+use util::sine::SineWave;
 
 mod util;
 
-#[cfg(os_coreaudio)]
 fn main() -> anyhow::Result<()> {
-    use interflow::backends::coreaudio::CoreAudioDriver;
-    use interflow::channel_map::{ChannelMap32, CreateBitset};
-    use interflow::prelude::*;
-    use std::sync::{
-        atomic::{AtomicBool, Ordering},
-        Arc,
-    };
-    use util::sine::SineWave;
-
-    struct MyCallback {
-        first_callback: Arc<AtomicBool>,
-        sine_wave: SineWave,
+    #[cfg(target_os = "macos")]
+    {
+        use interflow::backends::coreaudio::CoreAudioDriver;
+        run(CoreAudioDriver)
+    }
+    #[cfg(target_os = "windows")]
+    {
+        use interflow::backends::wasapi::WasapiDriver;
+        run(WasapiDriver::default())
     }
+    #[cfg(all(target_os = "linux", not(feature = "pipewire")))]
+    {
+        use interflow::backends::alsa::AlsaDriver;
+        run(AlsaDriver::default())
+    }
+    #[cfg(all(target_os = "linux", feature = "pipewire"))]
+    {
+        use interflow::backends::pipewire::PipewireDriver;
+        run(PipewireDriver::new()?)
+    }
+    #[cfg(not(any(target_os = "macos", target_os = "windows", target_os = "linux")))]
+    {
+        println!("This example is not available on this platform.");
+        Ok(())
+    }
+}
 
-    impl AudioOutputCallback for MyCallback {
-        fn on_output_data(&mut self, context: AudioCallbackContext, mut output: AudioOutput<f32>) {
-            if self.first_callback.swap(false, Ordering::SeqCst) {
-                println!(
-                    "Actual buffer size granted by OS: {}",
-                    output.buffer.num_samples()
-                );
-            }
+struct MyCallback {
+    first_callback: Arc<AtomicBool>,
+    sine_wave: SineWave,
+}
+
+impl AudioOutputCallback for MyCallback {
+    fn on_output_data(&mut self, context: AudioCallbackContext, mut output: AudioOutput<f32>) {
+        if self.first_callback.swap(false, Ordering::SeqCst) {
+            println!(
+                "Actual buffer size granted by OS: {}",
+                output.buffer.num_samples()
+            );
+        }
 
-            for mut frame in output.buffer.as_interleaved_mut().rows_mut() {
-                let sample = self
-                    .sine_wave
-                    .next_sample(context.stream_config.samplerate as f32);
-                for channel_sample in &mut frame {
-                    *channel_sample = sample;
-                }
+        for mut frame in output.buffer.as_interleaved_mut().rows_mut() {
+            let sample = self
+                .sine_wave
+                .next_sample(context.stream_config.samplerate as f32);
+            for channel_sample in &mut frame {
+                *channel_sample = sample;
             }
         }
     }
+}
 
+fn run<D>(driver: D) -> anyhow::Result<()>
+where
+    D: AudioDriver,
+    D::Device: AudioOutputDevice,
+    <D::Device as AudioDevice>::Error: std::error::Error + Send + Sync + 'static,
+    <D::Device as AudioOutputDevice>::StreamHandle<MyCallback>: AudioStreamHandle<MyCallback>,
+    <<D::Device as AudioOutputDevice>::StreamHandle<MyCallback> as AudioStreamHandle<MyCallback>>::Error:
+        std::error::Error + Send + Sync + 'static,
+{
     env_logger::init();
 
-    let driver = CoreAudioDriver;
+    let full_backend_name = std::any::type_name::<D>();
+    let backend_name = full_backend_name
+        .split("::")
+        .last()
+        .unwrap_or(full_backend_name);
+    println!("Using backend: {}", backend_name);
+
     let device = driver
         .default_device(DeviceType::OUTPUT)
         .expect("Failed to query for default output device")
@@ -80,8 +119,3 @@ fn main() -> anyhow::Result<()> {
     stream.eject()?;
     Ok(())
 }
-
-#[cfg(not(os_coreaudio))]
-fn main() {
-    println!("This example is only available on platforms that support CoreAudio (e.g. macOS).");
-}

src/backends/alsa/device.rs

@@ -57,6 +57,15 @@ impl AudioDevice for AlsaDevice {
         log::info!("TODO: enumerate configurations");
         None::<[StreamConfig; 0]>
     }
+
+    fn buffer_size_range(&self) -> Result<(Option<usize>, Option<usize>), Self::Error> {
+        // Query ALSA hardware parameters for the buffer size range.
+        let hwp = pcm::HwParams::any(&self.pcm)?;
+        Ok((
+            Some(hwp.get_buffer_size_min()? as usize),
+            Some(hwp.get_buffer_size_max()? as usize),
+        ))
+    }
 }
 
 impl AudioInputDevice for AlsaDevice {
@@ -153,7 +162,7 @@ impl AlsaDevice {
         Ok(StreamConfig {
             samplerate: samplerate as _,
             channels,
-            buffer_size_range: (None, None),
+            buffer_size_range: self.buffer_size_range()?,
             exclusive: false,
         })
     }

src/backends/pipewire/device.rs

@@ -67,6 +67,24 @@ impl AudioDevice for PipewireDevice {
     fn enumerate_configurations(&self) -> Option<impl IntoIterator<Item = StreamConfig>> {
         Some([])
     }
+
+    fn buffer_size_range(&self) -> Result<(Option<usize>, Option<usize>), Self::Error> {
+        // The buffer size range is stored in a string property from the ALSA compatibility API.
+        Ok(self
+            .properties()?
+            .map(|props| {
+                props
+                    .get("api.alsa.period-size-range")
+                    .map(|range_str| {
+                        let mut parts = range_str.split_whitespace();
+                        let min = parts.next().and_then(|s| s.parse().ok());
+                        let max = parts.next().and_then(|s| s.parse().ok());
+                        (min, max)
+                    })
+                    .unwrap_or((None, None))
+            })
+            .unwrap_or((None, None)))
+    }
 }
 
 impl AudioInputDevice for PipewireDevice {
@@ -77,7 +95,7 @@ impl AudioInputDevice for PipewireDevice {
             samplerate: 48000.0,
             channels: 0b11,
             exclusive: false,
-            buffer_size_range: (None, None),
+            buffer_size_range: self.buffer_size_range()?,
         })
     }
 
@@ -104,7 +122,7 @@ impl AudioOutputDevice for PipewireDevice {
             samplerate: 48000.0,
             channels: 0b11,
             exclusive: false,
-            buffer_size_range: (None, None),
+            buffer_size_range: self.buffer_size_range()?,
         })
     }
 

src/backends/pipewire/mod.rs

@@ -3,3 +3,5 @@ pub mod driver;
 pub mod error;
 pub mod stream;
 mod utils;
+
+pub use driver::PipewireDriver;

src/backends/pipewire/stream.rs

@@ -9,7 +9,6 @@ use crate::{
 use libspa::buffer::Data;
 use libspa::param::audio::{AudioFormat, AudioInfoRaw};
 use libspa::pod::Pod;
-use libspa::utils::Direction;
 use libspa_sys::{SPA_PARAM_EnumFormat, SPA_TYPE_OBJECT_Format};
 use pipewire::context::Context;
 use pipewire::keys;

src/backends/wasapi/device.rs

@@ -7,6 +7,7 @@ use crate::{
     Channel, DeviceType, StreamConfig,
 };
 use std::borrow::Cow;
+use windows::core::Interface;
 use windows::Win32::Media::Audio;
 
 /// Type of devices available from the WASAPI driver.
@@ -54,6 +55,59 @@ impl AudioDevice for WasapiDevice {
     fn enumerate_configurations(&self) -> Option<impl IntoIterator<Item = StreamConfig>> {
         None::<[StreamConfig; 0]>
     }
+
+    fn buffer_size_range(&self) -> Result<(Option<usize>, Option<usize>), Self::Error> {
+        let audio_client = self.device.activate::<Audio::IAudioClient>()?;
+        let format = unsafe { audio_client.GetMixFormat()?.read_unaligned() };
+        let samplerate = format.nSamplesPerSec;
+
+        // Attempt IAudioClient3/IAudioClient2 to get the buffer size range.
+        if let Ok(client) = audio_client.cast::<Audio::IAudioClient3>() {
+            let mut min_buffer_duration = 0;
+            let mut max_buffer_duration = 0;
+            // Based on the stream implementation, we assume event driven mode.
+            let event_driven = true;
+            unsafe {
+                client.GetBufferSizeLimits(
+                    &format,
+                    event_driven.into(),
+                    &mut min_buffer_duration,
+                    &mut max_buffer_duration,
+                )?;
+            }
+            // Convert from 100-nanosecond units to frames.
+            let to_frames = |period| (period as u64 * samplerate as u64 / 10_000_000) as usize;
+            return Ok((
+                Some(to_frames(min_buffer_duration)),
+                Some(to_frames(max_buffer_duration)),
+            ));
+        }
+        if let Ok(client) = audio_client.cast::<Audio::IAudioClient2>() {
+            let mut min_buffer_duration = 0;
+            let mut max_buffer_duration = 0;
+            let event_driven = true;
+            unsafe {
+                client.GetBufferSizeLimits(
+                    &format,
+                    event_driven.into(),
+                    &mut min_buffer_duration,
+                    &mut max_buffer_duration,
+                )?;
+            }
+            let to_frames = |period| (period as u64 * samplerate as u64 / 10_000_000) as usize;
+            return Ok((
+                Some(to_frames(min_buffer_duration)),
+                Some(to_frames(max_buffer_duration)),
+            ));
+        }
+
+        // Fallback to GetBufferSize for older WASAPI versions.
+        let frame_size = unsafe { audio_client.GetBufferSize() }.ok();
+        Ok((
+            frame_size.map(|v| v as usize),
+            frame_size.map(|v| v as usize),
+        ))
+    }
 }
 
 impl AudioInputDevice for WasapiDevice {
@@ -62,14 +116,11 @@ impl AudioInputDevice for WasapiDevice {
     fn default_input_config(&self) -> Result<StreamConfig, Self::Error> {
         let audio_client = self.device.activate::<Audio::IAudioClient>()?;
         let format = unsafe { audio_client.GetMixFormat()?.read_unaligned() };
-        let frame_size = unsafe { audio_client.GetBufferSize() }
-            .map(|i| i as usize)
-            .ok();
         Ok(StreamConfig {
             channels: 0u32.with_indices(0..format.nChannels as _),
             exclusive: false,
             samplerate: format.nSamplesPerSec as _,
-            buffer_size_range: (frame_size, frame_size),
+            buffer_size_range: self.buffer_size_range()?,
         })
     }
 
@@ -92,14 +143,11 @@ impl AudioOutputDevice for WasapiDevice {
     fn default_output_config(&self) -> Result<StreamConfig, Self::Error> {
         let audio_client = self.device.activate::<Audio::IAudioClient>()?;
         let format = unsafe { audio_client.GetMixFormat()?.read_unaligned() };
-        let frame_size = unsafe { audio_client.GetBufferSize() }
-            .map(|i| i as usize)
-            .ok();
         Ok(StreamConfig {
             channels: 0u32.with_indices(0..format.nChannels as _),
             exclusive: false,
             samplerate: format.nSamplesPerSec as _,
-            buffer_size_range: (frame_size, frame_size),
+            buffer_size_range: self.buffer_size_range()?,
         })
     }
 

src/backends/wasapi/stream.rs

@@ -483,7 +483,7 @@ pub(crate) fn is_output_config_supported(
     device: WasapiMMDevice,
     stream_config: &StreamConfig,
 ) -> bool {
-    let mut try_ = || unsafe {
+    let try_ = || unsafe {
         let audio_client: Audio::IAudioClient = device.activate()?;
         let sharemode = if stream_config.exclusive {
             Audio::AUDCLNT_SHAREMODE_EXCLUSIVE

src/lib.rs

@@ -3,8 +3,6 @@
 
 use bitflags::bitflags;
 use std::borrow::Cow;
-use std::fmt;
-use std::fmt::Formatter;
 
 use crate::audio_buffer::{AudioMut, AudioRef};
 use crate::channel_map::ChannelMap32;