remove reverse playback support for streaming sounds

There's some pretty serious issues with garbled audio when streaming mp3s and oggs backwards, and from the investigation I've done so far, I don't think they will be trivial to fix.

Author: tesselode

changelog.md

@@ -1,3 +1,10 @@
+# v0.8.3 - May 28, 2023
+
+This release removes reverse playback support for streaming sounds. There's pretty
+serious issues with garbled audio when streaming an mp3 or ogg file backwards,
+and based the initial investigation, these issues won't be trivial to fix.
+This feature may return in the future, but for now, you should not rely on it.
+
 # v0.8.2 - May 27, 2023
 
 - Fix errors when streaming some ogg files

crates/kira/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "kira"
-version = "0.8.2"
+version = "0.8.3"
 authors = ["Andrew Minnich <aminnich3@gmail.com>"]
 edition = "2018"
 license = "MIT OR Apache-2.0"

crates/kira/src/sound/streaming/settings.rs

@@ -14,8 +14,6 @@ pub struct StreamingSoundSettings {
 	pub playback_region: Region,
 	/// The portion of the sound that should be looped.
 	pub loop_region: Option<Region>,
-	/// Whether the sound should be played in reverse.
-	pub reverse: bool,
 	/// The volume of the sound.
 	pub volume: Value<Volume>,
 	/// The playback rate of the sound.
@@ -39,7 +37,6 @@ impl StreamingSoundSettings {
 			start_time: StartTime::Immediate,
 			playback_region: Region::default(),
 			loop_region: None,
-			reverse: false,
 			volume: Value::Fixed(Volume::Amplitude(1.0)),
 			playback_rate: Value::Fixed(PlaybackRate::Factor(1.0)),
 			panning: Value::Fixed(0.5),
@@ -128,11 +125,6 @@ impl StreamingSoundSettings {
 		}
 	}
 
-	/// Sets whether the sound should be played in reverse.
-	pub fn reverse(self, reverse: bool) -> Self {
-		Self { reverse, ..self }
-	}
-
 	/**
 	Sets the volume of the sound.
 

crates/kira/src/sound/streaming/sound.rs

@@ -250,7 +250,7 @@ impl Sound for StreamingSound {
 			self.fractional_position as f32,
 		);
 		self.fractional_position +=
-			self.sample_rate as f64 * self.playback_rate.value().as_factor() * dt;
+			self.sample_rate as f64 * self.playback_rate.value().as_factor().max(0.0) * dt;
 		while self.fractional_position >= 1.0 {
 			self.fractional_position -= 1.0;
 			self.frame_consumer.pop();

crates/kira/src/sound/streaming/sound/decode_scheduler.rs

@@ -64,7 +64,7 @@ impl<Error: Send + 'static> DecodeScheduler<Error> {
 			transport: Transport::new(
 				settings.playback_region,
 				settings.loop_region,
-				settings.reverse,
+				false,
 				sample_rate,
 				num_frames,
 			),
@@ -126,11 +126,7 @@ impl<Error: Send + 'static> DecodeScheduler<Error> {
 				index: self.transport.position,
 			})
 			.expect("could not push frame to frame producer");
-		if self.transport.reverse {
-			self.transport.decrement_position()
-		} else {
-			self.transport.increment_position();
-		}
+		self.transport.increment_position();
 		if !self.transport.playing {
 			self.shared.reached_end.store(true, Ordering::SeqCst);
 			return Ok(NextStep::End);

crates/kira/src/sound/streaming/sound/test.rs

@@ -1097,30 +1097,6 @@ fn seek_by() {
 	expect_frame_soon(Frame::from_mono(20.0).panned(0.5), &mut sound);
 }
 
-/// Tests that a `StreamingSound` can play in reverse.
-#[test]
-fn reverse() {
-	let data = StreamingSoundData {
-		decoder: Box::new(MockDecoder::new(
-			(0..10).map(|i| Frame::from_mono(i as f32)).collect(),
-		)),
-		settings: StreamingSoundSettings::new().reverse(true),
-	};
-	let (mut sound, _, mut scheduler) = data.split().unwrap();
-	while matches!(scheduler.run().unwrap(), NextStep::Continue) {}
-
-	for i in (4..=9).rev() {
-		assert_eq!(
-			sound.process(
-				1.0,
-				&MockClockInfoProviderBuilder::new(0).build(),
-				&MockModulatorValueProviderBuilder::new(0).build()
-			),
-			Frame::from_mono(i as f32).panned(0.5)
-		);
-	}
-}
-
 fn expect_frame_soon(expected_frame: Frame, sound: &mut StreamingSound) {
 	const NUM_SAMPLES_TO_WAIT: usize = 10;
 	for _ in 0..NUM_SAMPLES_TO_WAIT {