Update example with thumbpiano sampler demo. Loads one sample and plays it across three notes repetitively

examples/wav.rs

@@ -1,6 +1,16 @@
-extern crate find_folder;
-extern crate hound;
-extern crate portaudio as pa;
+extern crate find_folder; // For easily finding the assets folder.
+extern crate portaudio as pa; // For audio I/O
+extern crate pitch_calc as pitch; // To work with musical notes.
+extern crate sample; // To convert portaudio sample buffers to frames.
+extern crate sampler;
+
+use sampler::Sampler;
+
+const CHANNELS: i32 = 2;
+const SAMPLE_RATE: f64 = 44_100.0;
+const FRAMES_PER_BUFFER: u32 = 64;
+const THUMB_PIANO: &'static str = "thumbpiano A#3.wav";
+
 
 fn main() {
     run().unwrap();
@@ -8,27 +18,34 @@ fn main() {
 
 fn run() -> Result<(), pa::Error> {
 
-    let mut samples = {
-        let assets = find_folder::Search::ParentsThenKids(5, 5).for_folder("assets").unwrap();
-        let sample_file = assets.join("amen_brother.wav");
-        let mut reader = hound::WavReader::open(&sample_file).unwrap();
-        reader.samples().collect::<Result<Vec<i16>, _>>().unwrap().into_iter()
-    };
+    // We'll create a sample map that maps a single sample to the entire note range.
+    let assets = find_folder::Search::ParentsThenKids(5, 5).for_folder("assets").unwrap();
+    let sample = sampler::Sample::from_wav_file(assets.join(THUMB_PIANO), SAMPLE_RATE).unwrap();
+    let sample_map = sampler::Map::from_single_sample(sample);
 
-    let pa = try!(pa::PortAudio::new());
+    // Create a polyphonic sampler.
+    let mut sampler = Sampler::poly((), sample_map).num_voices(4);
 
-    const CHANNELS: i32 = 1;
-    const SAMPLE_RATE: f64 = 44_100.0;
-    const FRAMES_PER_BUFFER: u32 = 64;
+    // Initialise PortAudio and create an output stream.
+    let pa = try!(pa::PortAudio::new());
+    let settings = 
+        try!(pa.default_output_stream_settings::<i16>(CHANNELS, SAMPLE_RATE, FRAMES_PER_BUFFER));
 
-    let settings = try!(pa.default_output_stream_settings(CHANNELS, SAMPLE_RATE, FRAMES_PER_BUFFER));
     let callback = move |pa::OutputStreamCallbackArgs { buffer, .. }| {
-        for sample in buffer.iter_mut() {
-            *sample = match samples.next() {
-                Some(s) => s,
-                None => return pa::Complete,
-            };
+        let buffer: &mut [[i16; CHANNELS as usize]] =
+            sample::slice::to_frame_slice_mut(buffer).unwrap();
+        sample::slice::equilibrium(buffer);
+
+        // If the sampler is not currently active, play a note.
+        if !sampler.is_active() {
+            let vel = 0.3;
+            sampler.note_on(pitch::LetterOctave(pitch::Letter::Ash, 3).to_hz(), vel);
+            sampler.note_on(pitch::LetterOctave(pitch::Letter::Dsh, 3).to_hz(), vel);
+            sampler.note_on(pitch::LetterOctave(pitch::Letter::Gsh, 1).to_hz(), vel);
         }
+
+        sampler.fill_slice(buffer, SAMPLE_RATE);
+
         pa::Continue
     };
 
@@ -36,7 +53,9 @@ fn run() -> Result<(), pa::Error> {
 
     try!(stream.start());
 
-    while let Ok(true) = stream.is_active() {}
+    while let Ok(true) = stream.is_active() {
+        std::thread::sleep(std::time::Duration::from_millis(16));
+    }
 
     try!(stream.stop());
     try!(stream.close());