Voice Rework -- Events, Track Queues (#806)

This implements a proof-of-concept for an improved audio frontend. The largest change is the introduction of events and event handling: both by time elapsed and by track events, such as ending or looping. Following on from this, the library now includes a basic, event-driven track queue system (which people seem to ask for unusually often). A new sample, `examples/13_voice_events`, demonstrates both the `TrackQueue` system and some basic events via the `~queue` and `~play_fade` commands.

Locks are removed from around the control of `Audio` objects, which should allow the backend to be moved to a more granular futures-based backend solution in a cleaner way.

src/input/cached/tests.rs

@@ -0,0 +1,79 @@
+use super::*;
+use crate::{
+    constants::*,
+    input::{error::Error, ffmpeg, Codec, Container, Input, Reader},
+    test_utils::*,
+};
+use audiopus::{coder::Decoder, Bitrate, Channels, SampleRate};
+use byteorder::{LittleEndian, ReadBytesExt};
+use std::io::{Cursor, Read};
+
+#[tokio::test]
+async fn streamcatcher_preserves_file() {
+    let input = make_sine(50 * MONO_FRAME_SIZE, true);
+    let input_len = input.len();
+
+    let mut raw = default_config(raw_cost_per_sec(true))
+        .build(Cursor::new(input.clone()))
+        .map_err(Error::Streamcatcher)
+        .unwrap();
+
+    let mut out_buf = vec![];
+    let read = raw.read_to_end(&mut out_buf).unwrap();
+
+    assert_eq!(input_len, read);
+
+    assert_eq!(input, out_buf);
+}
+
+#[test]
+fn compressed_scans_frames_decodes_mono() {
+    let data = one_s_compressed_sine(false);
+    run_through_dca(data.raw);
+}
+
+#[test]
+fn compressed_scans_frames_decodes_stereo() {
+    let data = one_s_compressed_sine(true);
+    run_through_dca(data.raw);
+}
+
+#[test]
+fn compressed_triggers_valid_passthrough() {
+    let mut input = Input::from(one_s_compressed_sine(true));
+
+    assert!(input.supports_passthrough());
+
+    let mut opus_buf = [0u8; 10_000];
+    let mut signal_buf = [0i16; 1920];
+
+    let opus_len = input.read_opus_frame(&mut opus_buf[..]).unwrap();
+
+    let mut decoder = Decoder::new(SampleRate::Hz48000, Channels::Stereo).unwrap();
+    decoder
+        .decode(Some(&opus_buf[..opus_len]), &mut signal_buf[..], false)
+        .unwrap();
+}
+
+fn one_s_compressed_sine(stereo: bool) -> Compressed {
+    let data = make_sine(50 * MONO_FRAME_SIZE, stereo);
+
+    let input = Input::new(stereo, data.into(), Codec::FloatPcm, Container::Raw, None);
+
+    Compressed::new(input, Bitrate::BitsPerSecond(128_000)).unwrap()
+}
+
+fn run_through_dca(mut src: impl Read) {
+    let mut decoder = Decoder::new(SampleRate::Hz48000, Channels::Stereo).unwrap();
+
+    let mut pkt_space = [0u8; 10_000];
+    let mut signals = [0i16; 1920];
+
+    while let Ok(frame_len) = src.read_i16::<LittleEndian>() {
+        let pkt_len = src.read(&mut pkt_space[..frame_len as usize]).unwrap();
+
+        decoder
+            .decode(Some(&pkt_space[..pkt_len]), &mut signals[..], false)
+            .unwrap();
+    }
+}