gets buffersize range and allows to set buffersize for alsa

Cargo.toml

@@ -22,8 +22,8 @@ hound = "3.4"
 ringbuf = "0.1.6"
 
 [target.'cfg(target_os = "windows")'.dependencies]
-winapi = { path = "../winapi-rs", version = "0.3", features = ["audiosessiontypes", "audioclient", "coml2api", "combaseapi", "debug", "devpkey", "errhandlingapi", "handleapi", "ksmedia", "mmdeviceapi", "objbase", "std", "synchapi", "winbase", "winuser"] }
-# winapi = { version = "0.3", features = ["audiosessiontypes", "audioclient", "coml2api", "combaseapi", "debug", "devpkey", "handleapi", "ksmedia", "mmdeviceapi", "objbase", "profileapi", "std", "synchapi", "winbase", "winuser"] }
+# winapi = { path = "../winapi-rs", version = "0.3", features = ["audiosessiontypes", "audioclient", "coml2api", "combaseapi", "debug", "devpkey", "errhandlingapi", "handleapi", "ksmedia", "mmdeviceapi", "objbase", "std", "synchapi", "winbase", "winuser"] }
+winapi = { version = "0.3", features = ["audiosessiontypes", "audioclient", "coml2api", "combaseapi", "debug", "devpkey", "handleapi", "ksmedia", "mmdeviceapi", "objbase", "profileapi", "std", "synchapi", "winbase", "winuser"] }
 asio-sys = { version = "0.1", path = "asio-sys", optional = true }
 parking_lot = "0.9"
 

examples/beep.rs

@@ -9,7 +9,7 @@ fn main() -> Result<(), anyhow::Error> {
         .default_output_device()
         .expect("failed to find a default output device");
     let config = device.default_output_config()?;
-
+    println!("{:#?}", &config);
     match config.sample_format() {
         cpal::SampleFormat::F32 => run::<f32>(&device, &config.into())?,
         cpal::SampleFormat::I16 => run::<i16>(&device, &config.into())?,

examples/feedback.rs

@@ -29,8 +29,9 @@ fn main() -> Result<(), anyhow::Error> {
     println!("Using default output device: \"{}\"", output_device.name()?);
 
     // We'll try and use the same configuration between streams to keep it simple.
-    let config: cpal::StreamConfig = input_device.default_input_config()?.into();
-
+    let mut config: cpal::StreamConfig = input_device.default_input_config()?.into();
+    config.buffer_size = cpal::BufferSize::Fixed(1024);
+    
     // Create a delay in case the input and output devices aren't synced.
     let latency_frames = (LATENCY_MS / 1_000.0) * config.sample_rate.0 as f32;
     let latency_samples = latency_frames as usize * config.channels as usize;
@@ -47,6 +48,7 @@ fn main() -> Result<(), anyhow::Error> {
     }
 
     let input_data_fn = move |data: &[f32], _: &cpal::InputCallbackInfo| {
+        println!("data len = {}", data.len());
         let mut output_fell_behind = false;
         for &sample in data {
             if producer.push(sample).is_err() {

src/host/alsa/mod.rs

@@ -3,10 +3,10 @@ extern crate libc;
 
 use self::alsa::poll::Descriptors;
 use crate::{
-    BackendSpecificError, BufferSize, BuildStreamError, ChannelCount, Data, DefaultStreamConfigError,
-    DeviceNameError, DevicesError, InputCallbackInfo, OutputCallbackInfo, PauseStreamError,
-    PlayStreamError, SampleFormat, SampleRate, StreamConfig, StreamError, SupportedBufferSizeRange, SupportedStreamConfig,
-    SupportedStreamConfigRange, SupportedStreamConfigsError,
+    BackendSpecificError, BuildStreamError, ChannelCount, Data, DefaultStreamConfigError,
+    BufferSize, DeviceNameError, DevicesError, InputCallbackInfo, OutputCallbackInfo, PauseStreamError, 
+    PlayStreamError, SampleFormat, SampleRate, StreamConfig, StreamError, SupportedBufferSizeRange, 
+    SupportedStreamConfig, SupportedStreamConfigRange, SupportedStreamConfigsError,
 };
 use std::convert::TryInto;
 use std::sync::Arc;
@@ -343,8 +343,8 @@ impl Device {
         let max_buffer_size = hw_params.get_buffer_size_max()?;
 
         let buffer_size_range = SupportedBufferSizeRange {
-            min: min_buffer_size,
-            max: max_buffer_size,
+            min: min_buffer_size as u32,
+            max: max_buffer_size as u32,
             requires_power_of_two: false,
         };
 
@@ -358,7 +358,7 @@ impl Device {
                         channels: channels.clone(),
                         min_sample_rate: SampleRate(min_rate as u32),
                         max_sample_rate: SampleRate(max_rate as u32),
-                        buffer_size: buffer_size_range,
+                        buffer_size: buffer_size_range.clone(),
                         sample_format: sample_format,
                     });
                 }
@@ -900,6 +900,11 @@ fn set_hw_params_from_format<'a>(
     hw_params.set_rate(config.sample_rate.0, alsa::ValueOr::Nearest)?;
     hw_params.set_channels(config.channels as u32)?;
 
+    match config.buffer_size {
+        BufferSize::Fixed(v) => hw_params.set_buffer_size(v as i64)?,
+        BufferSize::Default => (),
+    }
+
     // If this isn't set manually a overlarge buffer may be used causing audio delay
     let mut hw_params_copy = hw_params.clone();
     if let Err(_) = hw_params.set_buffer_time_near(100_000, alsa::ValueOr::Nearest) {

src/lib.rs

@@ -181,7 +181,13 @@ pub type ChannelCount = u16;
 pub struct SampleRate(pub u32);
 
 /// The desired number of frames for the hardware buffer.
-pub type BufferSize = u32;
+pub type FrameCount = u32;
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub enum BufferSize {
+    Default,
+    Fixed(FrameCount),
+}
 
 /// The set of parameters used to describe how to open a stream.
 ///
@@ -197,8 +203,8 @@ pub struct StreamConfig {
 /// and if requested buffersize must be a power of 2 value.
 #[derive(Clone, Debug, Eq, PartialEq)]
 pub struct SupportedBufferSizeRange {
-    pub min: BufferSize,
-    pub max: BufferSize,
+    pub min: FrameCount,
+    pub max: FrameCount,
     pub requires_power_of_two: bool,
 }
 
@@ -223,7 +229,7 @@ pub struct SupportedStreamConfigRange {
 pub struct SupportedStreamConfig {
     channels: ChannelCount,
     sample_rate: SampleRate,
-    buffer_size: BufferSize,
+    buffer_size: SupportedBufferSizeRange,
     sample_format: SampleFormat,
 }
 
@@ -305,8 +311,8 @@ impl SupportedStreamConfig {
         self.sample_rate
     }
 
-    pub fn buffer_size(&self) -> BufferSize {
-        self.buffer_size
+    pub fn buffer_size(&self) -> &SupportedBufferSizeRange {
+        &self.buffer_size
     }
 
     pub fn sample_format(&self) -> SampleFormat {
@@ -317,7 +323,7 @@ impl SupportedStreamConfig {
         StreamConfig {
             channels: self.channels,
             sample_rate: self.sample_rate,
-            buffer_size: self.buffer_size,
+            buffer_size: BufferSize::Default,
         }
     }
 }
@@ -523,23 +529,29 @@ impl SupportedStreamConfigRange {
 
     /// Retrieve a `SupportedStreamConfig` with the given sample rate and buffer size.
     ///
-    /// **panic!**s if the given `sample_rate` or the give `buffer_size` is outside the range specified within this
+    /// **panic!**s if the given `sample_rate` is outside the range specified within this
     /// `SupportedStreamConfigRange` instance.
-    pub fn with_sample_rate_and_buffer_size(
+    pub fn with_sample_rate(
         self,
         sample_rate: SampleRate,
-        buffer_size: BufferSize,
     ) -> SupportedStreamConfig {
         assert!(self.min_sample_rate <= sample_rate && sample_rate <= self.max_sample_rate);
-        assert!(self.buffer_size.min <= buffer_size && buffer_size <= self.buffer_size.max);
-        if self.buffer_size.requires_power_of_two {
-            assert!(buffer_size.is_power_of_two());
-        }
         SupportedStreamConfig {
             channels: self.channels,
             sample_rate: self.max_sample_rate,
             sample_format: self.sample_format,
-            buffer_size,
+            buffer_size: self.buffer_size,
+        }
+    }
+
+    /// Turns this `SupportedStreamConfigRange` into a `SupportedStreamConfig` corresponding to the maximum samples rate.
+    #[inline]
+    pub fn with_max_sample_rate(self) -> SupportedStreamConfig {
+        SupportedStreamConfig {
+            channels: self.channels,
+            sample_rate: self.max_sample_rate,
+            sample_format: self.sample_format,
+            buffer_size: self.buffer_size,
         }
     }