librespot/playback/src/audio_backend/alsa.rs

use super::{Open, Sink};
use std::io;
use alsa::{PCM, Stream, Mode, Format, Access};

pub struct AlsaSink(Option<PCM>, String);

impl Open for AlsaSink {
   fn open(device: Option<String>) -> AlsaSink {
        info!("Using alsa sink");

        let name = device.unwrap_or("default".to_string());

        AlsaSink(None, name)
    }
}

impl Sink for AlsaSink {
    fn start(&mut self) -> io::Result<()> {
        if self.0.is_none() {
            match PCM::open(&*self.1,
                                    Stream::Playback, Mode::Blocking,
                                    Format::Signed16, Access::Interleaved,
                                    2, 44100) {
                Ok(f) => self.0 = Some(f),
                Err(e) => {
                    error!("Alsa error PCM open {}", e); 
                    return Err(io::Error::new(io::ErrorKind::Other, "Alsa error: PCM open failed"));
                }
            }
        }
        Ok(())
    }

    fn stop(&mut self) -> io::Result<()> {
        self.0 = None;
        Ok(())
    }

    fn write(&mut self, data: &[i16]) -> io::Result<()> {
        self.0.as_mut().unwrap().write_interleaved(&data).unwrap();
        Ok(())
    }
}