add SDL backend based on sdl2 crate

Cargo.lock

@@ -837,6 +837,7 @@ dependencies = [
  "log 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "portaudio-rs 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rodio 0.8.1 (git+https://github.com/tomaka/rodio)",
+ "sdl2 0.32.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1031,6 +1032,16 @@ dependencies = [
  "memchr 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "num"
+version = "0.1.42"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "num-integer 0.1.39 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-iter 0.1.37 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "num-bigint"
 version = "0.1.44"
@@ -1050,6 +1061,15 @@ dependencies = [
  "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "num-iter"
+version = "0.1.37"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "num-integer 0.1.39 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "num-traits"
 version = "0.1.43"
@@ -1467,6 +1487,27 @@ name = "scopeguard"
 version = "0.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "sdl2"
+version = "0.32.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.50 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num 0.1.42 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "sdl2-sys 0.32.5 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "sdl2-sys"
+version = "0.32.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cfg-if 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "semver"
 version = "0.9.0"
@@ -2281,8 +2322,10 @@ dependencies = [
 "checksum nix 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)" = "d37e713a259ff641624b6cb20e3b12b2952313ba36b6823c0f16e6cfd9e5de17"
 "checksum nodrop 0.1.13 (registry+https://github.com/rust-lang/crates.io-index)" = "2f9667ddcc6cc8a43afc9b7917599d7216aa09c463919ea32c59ed6cac8bc945"
 "checksum nom 3.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "05aec50c70fd288702bcd93284a8444607f3292dbdf2a30de5ea5dcdbe72287b"
+"checksum num 0.1.42 (registry+https://github.com/rust-lang/crates.io-index)" = "4703ad64153382334aa8db57c637364c322d3372e097840c72000dabdcf6156e"
 "checksum num-bigint 0.1.44 (registry+https://github.com/rust-lang/crates.io-index)" = "e63899ad0da84ce718c14936262a41cee2c79c981fc0a0e7c7beb47d5a07e8c1"
 "checksum num-integer 0.1.39 (registry+https://github.com/rust-lang/crates.io-index)" = "e83d528d2677f0518c570baf2b7abdcf0cd2d248860b68507bdcb3e91d4c0cea"
+"checksum num-iter 0.1.37 (registry+https://github.com/rust-lang/crates.io-index)" = "af3fdbbc3291a5464dc57b03860ec37ca6bf915ed6ee385e7c6c052c422b2124"
 "checksum num-traits 0.1.43 (registry+https://github.com/rust-lang/crates.io-index)" = "92e5113e9fd4cc14ded8e499429f396a20f98c772a47cc8622a736e1ec843c31"
 "checksum num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)" = "0b3a5d7cc97d6d30d8b9bc8fa19bf45349ffe46241e8816f50f62f6d6aaabee1"
 "checksum num_cpus 1.10.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1a23f0ed30a54abaa0c7e83b1d2d87ada7c3c23078d1d87815af3e3b6385fbba"
@@ -2334,6 +2377,8 @@ dependencies = [
 "checksum safemem 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "8dca453248a96cb0749e36ccdfe2b0b4e54a61bfef89fb97ec621eb8e0a93dd9"
 "checksum scoped-tls 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "332ffa32bf586782a3efaeb58f127980944bbc8c4d6913a86107ac2a5ab24b28"
 "checksum scopeguard 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)" = "94258f53601af11e6a49f722422f6e3425c52b06245a5cf9bc09908b174f5e27"
+"checksum sdl2 0.32.1 (registry+https://github.com/rust-lang/crates.io-index)" = "0ebf85f207d42e4da59fa31fff977be5ff0b224873506c4bd70cc1c94b331593"
+"checksum sdl2-sys 0.32.5 (registry+https://github.com/rust-lang/crates.io-index)" = "e82803e85c2e6178d28886cef25b2c53afc2eecaeff739f2247f23ed3352e6c1"
 "checksum semver 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1d7eb9ef2c18661902cc47e535f9bc51b78acd254da71d375c2f6720d9a40403"
 "checksum semver-parser 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "388a1df253eca08550bef6c72392cfe7c30914bf41df5269b68cbd6ff8f570a3"
 "checksum serde 1.0.89 (registry+https://github.com/rust-lang/crates.io-index)" = "92514fb95f900c9b5126e32d020f5c6d40564c27a5ea6d1d7d9f157a96623560"

Cargo.toml

@@ -61,6 +61,7 @@ portaudio-backend = ["librespot-playback/portaudio-backend"]
 pulseaudio-backend = ["librespot-playback/pulseaudio-backend"]
 jackaudio-backend = ["librespot-playback/jackaudio-backend"]
 rodio-backend = ["librespot-playback/rodio-backend"]
+sdl-backend = ["librespot-playback/sdl-backend"]
 
 with-tremor = ["librespot-audio/with-tremor"]
 with-vorbis = ["librespot-audio/with-vorbis"]

playback/Cargo.toml

@@ -22,6 +22,7 @@ jack            = { version = "0.5.3", optional = true }
 libc            = { version = "0.2", optional = true }
 rodio           = { git = "https://github.com/tomaka/rodio", optional = true, default-features = false }
 cpal            = { version = "*", optional = true }
+sdl2            = { version = "0.32", optional = true }
 
 [features]
 alsa-backend = ["alsa"]
@@ -29,3 +30,4 @@ portaudio-backend = ["portaudio-rs"]
 pulseaudio-backend = ["libpulse-sys", "libc"]
 jackaudio-backend = ["jack"]
 rodio-backend = ["rodio", "cpal"]
+sdl-backend = ["sdl2"]

playback/src/audio_backend/mod.rs

@@ -38,6 +38,10 @@ use self::jackaudio::JackSink;
 mod rodio;
 #[cfg(feature = "rodio-backend")]
 use self::rodio::RodioSink;
+#[cfg(feature = "sdl-backend")]
+mod sdl;
+#[cfg(feature = "sdl-backend")]
+use self::sdl::SdlSink;
 
 mod pipe;
 use self::pipe::StdoutSink;
@@ -53,6 +57,8 @@ pub const BACKENDS: &'static [(&'static str, fn(Option<String>) -> Box<Sink>)] =
     ("jackaudio", mk_sink::<JackSink>),
     #[cfg(feature = "rodio-backend")]
     ("rodio", mk_sink::<RodioSink>),
+    #[cfg(feature = "sdl-backend")]
+    ("sdl", mk_sink::<SdlSink>),
     ("pipe", mk_sink::<StdoutSink>),
 ];
 

playback/src/audio_backend/sdl.rs

@@ -0,0 +1,56 @@
+use super::{Open, Sink};
+use sdl2::audio::{AudioQueue, AudioSpecDesired};
+use std::{io, thread, time};
+
+type Channel = i16;
+
+pub struct SdlSink {
+    queue: AudioQueue<Channel>,
+}
+
+impl Open for SdlSink {
+    fn open(device: Option<String>) -> SdlSink {
+        debug!("Using SDL sink");
+
+        if device.is_some() {
+            panic!("SDL sink does not support specifyng a device name");
+        }
+
+        let ctx = sdl2::init().expect("Could not init SDL");
+        let audio = ctx.audio().expect("Could not init SDL audio subsystem");
+
+        let desired_spec = AudioSpecDesired {
+            freq: Some(44_100),
+            channels: Some(2),
+            samples: None, // default
+        };
+        let queue = audio
+            .open_queue(None, &desired_spec)
+            .expect("Could not open SDL audio device");
+
+        SdlSink { queue: queue }
+    }
+}
+
+impl Sink for SdlSink {
+    fn start(&mut self) -> io::Result<()> {
+        self.queue.clear(); //
+        self.queue.resume();
+        Ok(())
+    }
+
+    fn stop(&mut self) -> io::Result<()> {
+        self.queue.pause();
+        self.queue.clear();
+        Ok(())
+    }
+
+    fn write(&mut self, data: &[i16]) -> io::Result<()> {
+        while self.queue.size() > (2 * 2 * 44_100) {
+            // sleep and wait for sdl thread to drain the queue a bit
+            thread::sleep(time::Duration::from_millis(10));
+        }
+        self.queue.queue(data);
+        Ok(())
+    }
+}

playback/src/lib.rs

@@ -16,6 +16,9 @@ extern crate libpulse_sys;
 #[cfg(feature = "jackaudio-backend")]
 extern crate jack;
 
+#[cfg(feature = "sdl-backend")]
+extern crate sdl2;
+
 #[cfg(feature = "libc")]
 extern crate libc;