rascam/src/main.rs

extern crate sdl2;
extern crate toml;

#[macro_use]
extern crate serde_derive;
extern crate gst;
extern crate itertools;

use std::fs::File;
use std::io::prelude::*;
use std::sync::mpsc;

use itertools::Itertools;

use sdl2::event::Event;
use sdl2::pixels;


#[derive(Debug, Deserialize)]
struct Config {
    audio: AudioConfig,
    output: OutputConfig,
}

#[derive(Debug, Deserialize)]
struct AudioConfig {
    alsa_device: String,
    rate: u32,
}

#[derive(Debug, Deserialize)]
struct OutputConfig {
    directory: String,
    prefix: String,
}


fn read_config(path: &str) -> Config {

    let mut config_toml = String::new();

    let mut file = match File::open(path) {
        Ok(file) => file,
        Err(_) => panic!("Could not find config file!"),
    };

    file.read_to_string(&mut config_toml)
        .unwrap_or_else(|err| panic!("Error while reading config: [{}]", err));

    let config: Config = toml::from_str(&config_toml).unwrap_or_else(|err| {
        panic!("Error while parsing config: [{}]",  err)
    });

    return config;
}


fn handle_pipeline_events(bus_receiver : &mpsc::Receiver<gst::Message>) -> bool {

    while let Ok(msg) = bus_receiver.try_recv() {
        match msg.parse() {
            gst::Message::StateChangedParsed { ref old, ref new, .. } => {
                println!("element `{}` changed from {:?} to {:?}",
                            msg.src_name(), old, new);
            }
            gst::Message::ErrorParsed {ref error, ref debug, .. } => {
                println!("error msg from element `{}`: {}, {}. Quitting",
                            msg.src_name(), error.message(), debug);
                return true;
            }
            _ => {
                println!("msg of type `{}` from element `{}`",
                            msg.type_name(), msg.src_name());
            }
        }
    }
    return false;
}

fn get_max_samples(appsink : &gst::appsink::AppSink) -> Result<(f32, f32), &str>{
    match appsink.try_recv() {
        Ok(gst::appsink::Message::NewSample(sample))
            | Ok(gst::appsink::Message::NewPreroll(sample)) => {
            if let Some(buffer) = sample.buffer() {
                let (max0, max1) = buffer.map_read(|mapping| {
                    mapping.iter::<f32>().tuples().fold((0.0f32, 0.0f32), |(acc0, acc1), (sample0, sample1)| {
                        (acc0.max(sample0.abs()), acc1.max(sample1.abs()))
                    })
                }).unwrap();
                return Ok((max0, max1));
            }
            return Err("Unable to access samples");
        }
        Ok(gst::appsink::Message::Eos) => {
            return Err("Got no sample when polling. EOS");
        }
        Err(mpsc::TryRecvError::Empty) => {
            return Ok((0.0f32,0.0f32));
        }
        Err(mpsc::TryRecvError::Disconnected) => {
            return Err("Appsink got disconnected")
        }
    }
}

const SCREEN_WIDTH: u32 = 160;
const SCREEN_HEIGHT: u32 = 128;

fn main() {
    gst::init();

    let config = read_config("rascam.toml");


    let pipeline_str = format!("alsasrc device={} ! audio/x-raw,rate={},channels=2 ! queue ! tee name=apptee ! audioconvert ! flacenc ! filesink location={}/{}.flac apptee. ! queue ! audioconvert ! appsink name=appsink0 caps=\"audio/x-raw,format=F32LE,channels=2\"",
                               config.audio.alsa_device,
                               config.audio.rate,
                               config.output.directory,
                               config.output.prefix);

    println!("{}", pipeline_str);

    let mut pipeline = gst::Pipeline::new_from_str(&pipeline_str).unwrap();
    let mut mainloop = gst::MainLoop::new();
    let mut bus = pipeline.bus().expect("Couldn't get bus from pipeline");
    let bus_receiver = bus.receiver();
    let appsink = pipeline
        .get_by_name("appsink0")
        .expect("Couldn't get appsink from pipeline");
    let appsink = gst::AppSink::new_from_element(appsink);

    /*
    let sdl_context = sdl2::init().unwrap();
    let video_subsys = sdl_context.video().unwrap();
    let window = video_subsys.window("rascam", SCREEN_WIDTH, SCREEN_HEIGHT)
        .position_centered()
        .build()
        .unwrap();

    let mut canvas = window.into_canvas().build().unwrap();

    canvas.set_draw_color(pixels::Color::RGB(255, 255, 0));
    canvas.clear();
    canvas.present();
    */

    mainloop.spawn();
    pipeline.play();

    loop {
        if handle_pipeline_events(&bus_receiver) {
            break;
        }
        let result = get_max_samples(& appsink);
        match result {
            Ok((max0, max1)) => {
                println!("{} | {}", max0, max1);
            }
            Err(msg) => {
                println!("Error occured: {}", msg);
                break;
            }
        }
    }


    mainloop.quit();
}