From 96cdb4c375bbf869a6c15eabd7fc8476b802fe56 Mon Sep 17 00:00:00 2001
From: V Bota <VBota1@users.noreply.github.com>
Date: Fri, 6 Apr 2018 19:55:23 +0300
Subject: [PATCH] example record to wav

use portaudio for hw access
use hound::WavWriter for encoding stream to wav
---
 examples/record_to_wav | 141 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 141 insertions(+)
 create mode 100644 examples/record_to_wav

diff --git a/examples/record_to_wav b/examples/record_to_wav
new file mode 100644
index 0000000..5631aaa
--- /dev/null
+++ b/examples/record_to_wav
@@ -0,0 +1,141 @@
+//! A demonstration of recording to wav an input stream
+//!
+//! Audio from the default input device is stored in to a wav file
+
+extern crate portaudio;
+
+use std::time::{Duration, Instant};
+use std::thread::sleep;
+
+extern crate hound;
+use hound::WavWriter;
+
+use std::fs;
+use std::io;
+use std::mem;
+
+fn main() {
+    const CHANNELS: i32 = 2;
+    const SAMPLE_RATE: f64 = 44_100.0;
+    const FRAMES: u32 = 256;
+
+    let audio_port = match open_audio_port() {
+        Ok(port) => port,
+        Err(error) => panic!(String::from(error))
+    };
+
+    let input_index = match get_input_device_index(&audio_port) {
+        Ok(index) => index,
+        Err(error) => panic!(String::from(error))
+    };
+
+    let input_settings = match get_input_settings(input_index, &audio_port, SAMPLE_RATE, FRAMES, CHANNELS) {
+        Ok(settings) => settings,
+        Err(error) => panic!(String::from(error))
+    };
+
+    let mut wav_writer = match get_wav_writer("recorded.wav", CHANNELS, SAMPLE_RATE) {
+        Ok(writer) => writer,
+        Err(error) => panic!(error),
+    };
+
+    let callback = move |portaudio::InputStreamCallbackArgs { buffer, .. }| {
+        for &sample in buffer.iter() {
+            wav_writer.write_sample(sample).ok();
+        }
+
+        portaudio::Continue
+    };
+
+    // Construct a stream with input and output sample types of f32.
+    let mut stream = match audio_port.open_non_blocking_stream(input_settings, callback) {
+        Ok(strm) => strm,
+        Err(error) => panic!(error.to_string()),
+    };
+
+    match stream.start() {
+        Ok(_) => {}
+        Err(error) => panic!(error.to_string()),
+    };
+
+    let start = Instant::now();
+
+    let time_to_wait = &(5 as u64);
+    while start.elapsed().as_secs().lt(time_to_wait) {
+        sleep(Duration::new(1, 0));
+        println!("{}[s] passed", start.elapsed().as_secs() );
+    }
+
+    match close_stream(stream){
+        Ok(_) => {}
+        Err(error) => panic!(error),
+    };
+}
+
+fn get_wav_writer(path: &'static str, channels: i32, sample_rate: f64) -> Result<WavWriter<io::BufWriter<fs::File>>,String> {
+    let spec = wav_spec(channels, sample_rate);
+    match hound::WavWriter::create(path, spec) {
+        Ok(writer) => Ok(writer),
+        Err(error) => Err (String::from(format!("{}",error))),
+    }
+}
+
+fn wav_spec(channels: i32, sample_rate: f64) -> hound::WavSpec {
+    hound::WavSpec {
+        channels: channels as _,
+        sample_rate: sample_rate as _,
+        bits_per_sample: (mem::size_of::<f32>() * 8) as _,
+        sample_format: hound::SampleFormat::Float,
+    }
+}
+
+fn close_stream(mut stream: portaudio::Stream<portaudio::NonBlocking, portaudio::Input<f32>>) -> Result<String, String> {
+    match stream.stop() {
+        Ok(_) => {
+            Ok(String::from("Stream closed"))
+        },
+        Err(error) => {
+            Err(error.to_string())
+        },
+    }
+}
+
+fn open_audio_port() -> Result<portaudio::PortAudio, String>
+{
+    portaudio::PortAudio::new().or_else(|error| Err(String::from(format!("{}", error))))
+}
+
+fn get_input_device_index(audio_port: &portaudio::PortAudio) -> Result<portaudio::DeviceIndex, String>
+{
+    audio_port.default_input_device().or_else(|error| Err(String::from(format!("{}", error))))
+}
+
+fn get_input_latency(audio_port: &portaudio::PortAudio, input_index: portaudio::DeviceIndex) -> Result<f64, String>
+{
+    let input_device_information = audio_port.device_info(input_index).or_else(|error| Err(String::from(format!("{}", error))));
+    Ok(input_device_information.unwrap().default_low_input_latency)
+}
+
+fn get_input_stream_parameters(input_index: portaudio::DeviceIndex, latency: f64, channels: i32) -> Result<portaudio::StreamParameters<f32>, String>
+{
+    const INTERLEAVED: bool = true;
+    Ok(portaudio::StreamParameters::<f32>::new(input_index, channels, INTERLEAVED, latency))
+}
+
+fn get_input_settings(input_index: portaudio::DeviceIndex, audio_port: &portaudio::PortAudio, sample_rate: f64, frames: u32, channels: i32) -> Result<portaudio::InputStreamSettings<f32>, String>
+{
+    Ok(
+        portaudio::InputStreamSettings::new(
+            (get_input_stream_parameters(
+                input_index,
+                (get_input_latency(
+                    &audio_port,
+                    input_index,
+                ))?,
+                channels
+            ))?,
+            sample_rate,
+            frames,
+        )
+    )
+}