Add some formats-related functions

examples/beep.rs

@@ -3,6 +3,8 @@ extern crate cpal;
 fn main() {
     let mut channel = cpal::Channel::new();
 
+    assert!(channel.get_samples_format() == cpal::SampleFormat::U16);
+
     // producing a sinusoid
     let mut data_source =
         std::iter::iterate(0.0f32, |f| f + 0.03)

src/lib.rs

@@ -21,6 +21,15 @@ pub type ChannelsCount = u16;
 /// A `Buffer` object borrows the channel.
 pub struct Buffer<'a>(cpal_impl::Buffer<'a>);
 
+/// Format that each sample has.
+#[deriving(Clone, Show, PartialEq, Eq)]
+pub enum SampleFormat {
+    /// The value 0 corresponds to 0.
+    I16,
+    /// The value 0 corresponds to 32768.
+    U16,
+}
+
 impl Channel {
     pub fn new() -> Channel {
         let channel = cpal_impl::Channel::new();
@@ -34,6 +43,20 @@ impl Channel {
         self.0.get_channels()
     }
 
+    /// Returns the number of samples that are played per second.
+    ///
+    /// Common values are 22050 Hz or 44100 Hz.
+    pub fn get_samples_per_second(&self) -> u32 {
+        self.0.get_samples_per_second()
+    }
+
+    /// Returns the number of samples that are played per second.
+    ///
+    /// Common values are 22050 Hz or 44100 Hz.
+    pub fn get_samples_format(&self) -> SampleFormat {
+        self.0.get_samples_format()
+    }
+
     /// Adds some PCM data to the channel's buffer.
     ///
     /// This function returns a `Buffer` object that must be filled with the audio data.

src/wasapi/mod.rs

@@ -10,6 +10,8 @@ pub struct Channel {
     max_frames_in_buffer: winapi::UINT32,
     num_channels: winapi::WORD,
     bytes_per_frame: winapi::WORD,
+    samples_per_second: winapi::DWORD,
+    bits_per_sample: winapi::WORD,
     started: bool,
 }
 
@@ -30,6 +32,17 @@ impl Channel {
         self.num_channels as ::ChannelsCount
     }
 
+    pub fn get_samples_per_second(&self) -> u32 {
+        self.samples_per_second as u32
+    }
+
+    pub fn get_samples_format(&self) -> ::SampleFormat {
+        match self.bits_per_sample {
+            16 => ::SampleFormat::U16,
+            _ => unimplemented!(),
+        }
+    }
+
     pub fn append_data<'a>(&'a mut self) -> Buffer<'a> {
         unsafe {
             loop {
@@ -202,6 +215,8 @@ fn init() -> Result<Channel, String> {
             max_frames_in_buffer: max_frames_in_buffer,
             num_channels: format.nChannels,
             bytes_per_frame: format.nBlockAlign,
+            samples_per_second: format.nSamplesPerSec,
+            bits_per_sample: format.wBitsPerSample,
             started: false,
         })
     }