Implements Seek

CHANGELOG.md

@@ -8,6 +8,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]
 
 ### Changed
+- Adds a new method `try_seek` to all sources. It returns either an error or
+  seeks to the given position. A few sources are "unsupported" they return the
+  error `Unsupported`.
 - `Source` trait is now also implemented for `Box<dyn Source>` and `&mut Source`
 - `fn new_vorbis` is now also available when the `symphonia-vorbis` feature is enabled
 

Cargo.toml

@@ -17,6 +17,7 @@ lewton = { version = "0.10", optional = true }
 minimp3_fixed = { version = "0.5.4", optional = true}
 symphonia = { version = "0.5.2", optional = true, default-features = false }
 crossbeam-channel = { version = "0.5.8", optional = true }
+thiserror = "1.0.49"
 
 [features]
 default = ["flac", "vorbis", "wav", "mp3"]
@@ -38,6 +39,8 @@ symphonia-wav = ["symphonia/wav", "symphonia/pcm", "symphonia/adpcm"]
 
 [dev-dependencies]
 quickcheck = "0.9.2"
+rstest = "0.18.2"
+rstest_reuse = "0.6.0"
 
 [[example]]
 name = "music_m4a"

examples/seek_mp3.rs

@@ -0,0 +1,18 @@
+use std::io::BufReader;
+use std::time::Duration;
+
+fn main() {
+    let (_stream, handle) = rodio::OutputStream::try_default().unwrap();
+    let sink = rodio::Sink::try_new(&handle).unwrap();
+
+    let file = std::fs::File::open("assets/music.mp3").unwrap();
+    sink.append(rodio::Decoder::new(BufReader::new(file)).unwrap());
+
+    std::thread::sleep(std::time::Duration::from_secs(2));
+    sink.try_seek(Duration::from_secs(0)).unwrap();
+
+    std::thread::sleep(std::time::Duration::from_secs(2));
+    sink.try_seek(Duration::from_secs(4)).unwrap();
+
+    sink.sleep_until_end();
+}

src/buffer.rs

@@ -11,13 +11,14 @@
 //!
 
 use std::time::Duration;
-use std::vec::IntoIter as VecIntoIter;
 
+use crate::source::SeekError;
 use crate::{Sample, Source};
 
 /// A buffer of samples treated as a source.
 pub struct SamplesBuffer<S> {
-    data: VecIntoIter<S>,
+    data: Vec<S>,
+    pos: usize,
     channels: u16,
     sample_rate: u32,
     duration: Duration,
@@ -53,7 +54,8 @@ where
         );
 
         SamplesBuffer {
-            data: data.into_iter(),
+            data,
+            pos: 0,
             channels,
             sample_rate,
             duration,
@@ -84,6 +86,27 @@ where
     fn total_duration(&self) -> Option<Duration> {
         Some(self.duration)
     }
+
+    // this is fast because all the samples are in memory already
+    // and due to the constant sample_rate we can jump to the right
+    // sample directly
+    //
+    /// This jumps in memory till the sample for `pos`.
+    #[inline]
+    fn try_seek(&mut self, pos: Duration) -> Result<(), SeekError> {
+        let curr_channel = self.pos % self.channels() as usize;
+        let new_pos = pos.as_secs_f32() * self.sample_rate() as f32 * self.channels() as f32;
+        // saturate pos at the end of the source
+        let new_pos = new_pos as usize;
+        let new_pos = new_pos.min(self.data.len());
+
+        // make sure the next sample is for the right channel
+        let new_pos = new_pos.next_multiple_of(self.channels() as usize);
+        let new_pos = new_pos - curr_channel;
+
+        self.pos = new_pos;
+        Ok(())
+    }
 }
 
 impl<S> Iterator for SamplesBuffer<S>
@@ -94,12 +117,14 @@ where
 
     #[inline]
     fn next(&mut self) -> Option<S> {
-        self.data.next()
+        let sample = self.data.get(self.pos)?;
+        self.pos += 1;
+        Some(*sample)
     }
 
     #[inline]
     fn size_hint(&self) -> (usize, Option<usize>) {
-        self.data.size_hint()
+        (self.data.len(), Some(self.data.len()))
     }
 }
 
@@ -144,4 +169,32 @@ mod tests {
         assert_eq!(buf.next(), Some(6));
         assert_eq!(buf.next(), None);
     }
+
+    #[cfg(test)]
+    mod try_seek {
+        use super::*;
+        use std::time::Duration;
+
+        #[test]
+        fn channel_order_stays_correct() {
+            const SAMPLE_RATE: u32 = 100;
+            const CHANNELS: u16 = 2;
+            let mut buf = SamplesBuffer::new(
+                CHANNELS,
+                SAMPLE_RATE,
+                (0..2000i16).into_iter().collect::<Vec<_>>(),
+            );
+            buf.try_seek(Duration::from_secs(5)).unwrap();
+            assert_eq!(
+                buf.next(),
+                Some(5i16 * SAMPLE_RATE as i16 * CHANNELS as i16)
+            );
+
+            assert!(buf.next().is_some_and(|s| s % 2 == 1));
+            assert!(buf.next().is_some_and(|s| s % 2 == 0));
+
+            buf.try_seek(Duration::from_secs(6)).unwrap();
+            assert!(buf.next().is_some_and(|s| s % 2 == 1),);
+        }
+    }
 }

src/conversions/channels.rs

@@ -46,6 +46,12 @@ where
     pub fn into_inner(self) -> I {
         self.input
     }
+
+    /// Get mutable access to the iterator
+    #[inline]
+    pub fn inner_mut(&mut self) -> &mut I {
+        &mut self.input
+    }
 }
 
 impl<I> Iterator for ChannelCountConverter<I>

src/conversions/sample.rs

@@ -23,6 +23,12 @@ impl<I, O> DataConverter<I, O> {
     pub fn into_inner(self) -> I {
         self.input
     }
+
+    /// get mutable access to the iterator
+    #[inline]
+    pub fn inner_mut(&mut self) -> &mut I {
+        &mut self.input
+    }
 }
 
 impl<I, O> Iterator for DataConverter<I, O>

src/conversions/sample_rate.rs

@@ -102,6 +102,12 @@ where
         self.input
     }
 
+    /// get mutable access to the iterator
+    #[inline]
+    pub fn inner_mut(&mut self) -> &mut I {
+        &mut self.input
+    }
+
     fn next_input_frame(&mut self) {
         self.current_frame_pos_in_chunk += 1;
 

src/decoder/flac.rs

@@ -3,6 +3,7 @@ use std::io::{Read, Seek, SeekFrom};
 use std::mem;
 use std::time::Duration;
 
+use crate::source::SeekError;
 use crate::Source;
 
 use claxon::FlacReader;
@@ -79,6 +80,13 @@ where
         self.samples
             .map(|s| Duration::from_micros(s * 1_000_000 / self.sample_rate as u64))
     }
+
+    #[inline]
+    fn try_seek(&mut self, _: Duration) -> Result<(), SeekError> {
+        Err(SeekError::NotSupported {
+            underlying_source: std::any::type_name::<Self>(),
+        })
+    }
 }
 
 impl<R> Iterator for FlacDecoder<R>