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audio: Implement Mp3Decoder::seek_to_sample_frame

This commit is contained in:
Mike Welsh 2022-09-05 21:15:36 -07:00
parent fe46d5046a
commit e2f1f0174b
1 changed files with 23 additions and 6 deletions
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29
core/src/backend/audio/decoders/mp3.rs
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@ -159,7 +159,8 @@ pub mod symphonia {
}
impl Mp3Decoder {
const SAMPLE_BUFFER_DURATION: u64 = 4096;
// MP3 frames contain 1152 samples.
const SAMPLE_BUFFER_DURATION: u64 = 1152;
pub fn new<R: 'static + Read + Send + Sync>(reader: R) -> Result<Self, Error> {
let source = Box::new(io::ReadOnlySource::new(reader)) as Box<dyn io::MediaSource>;
@ -175,7 +176,7 @@ pub mod symphonia {
reader,
decoder,
sample_buf: audio::SampleBuffer::new(
Self::SAMPLE_BUFFER_DURATION,
0,
audio::SignalSpec::new(sample_rate, channels),
),
cur_sample: 0,
@ -223,7 +224,8 @@ pub mod symphonia {
while let Ok(packet) = self.reader.next_packet() {
match self.decoder.decode(&packet) {
Ok(decoded) => {
if self.sample_buf.is_empty() {
if self.sample_buf.capacity() < decoded.capacity() {
// Ensure our buffer has enough space for the decoded samples.
self.sample_buf = audio::SampleBuffer::new(
decoded.capacity() as core::units::Duration,
*decoded.spec(),
@ -271,15 +273,30 @@ pub mod symphonia {
impl SeekableDecoder for Mp3Decoder {
#[inline]
fn reset(&mut self) {
let _ = self.reader.seek(
self.seek_to_sample_frame(0);
}
#[inline]
fn seek_to_sample_frame(&mut self, frame: u32) {
// Seek to the desired position,
let seek_result = self.reader.seek(
formats::SeekMode::Accurate,
formats::SeekTo::TimeStamp { track_id: 0, ts: 0 },
formats::SeekTo::TimeStamp {
track_id: 0,
ts: frame.into(),
},
);
self.sample_buf.clear();
self.decoder.reset();
self.cur_sample = 0;
self.stream_ended = false;
self.next_frame();
// Seeking isn't exact, so we may end up slightly before our desired position.
// Pump samples until we get to the exact position.
let samples_remaining =
seek_result.map_or(0, |seek| seek.required_ts.saturating_sub(seek.actual_ts));
for _ in 0..samples_remaining {
self.next();
}
}
}