370 lines
12 KiB
Rust
370 lines
12 KiB
Rust
//! # Ogg/Vorbis Streaming Decoder
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//!
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//! This module implements a fully streaming Ogg/Vorbis decoder without relying
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//! on random access. It parses Ogg pages sequentially, assembles Vorbis packets,
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//! and decodes them with Lewton's low-level audio API, yielding 16-bit LE PCM.
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use std::{
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collections::VecDeque,
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io::{self, Read},
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pin::Pin,
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task::{Context, Poll},
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};
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use bytes::Bytes;
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use lewton::{
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audio::{self, read_audio_packet_generic, PreviousWindowRight},
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header::{self, read_header_comment, read_header_ident, read_header_setup, CommentHeader},
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samples::InterleavedSamples,
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};
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use tokio::{
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io::{
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self as tokio_io, AsyncRead, AsyncReadExt, AsyncWriteExt, ReadBuf,
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},
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sync::{mpsc, oneshot},
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};
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use crate::{common::ChannelReader, pcm::StreamInfo, stream::ManagedAsyncReader};
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/// Size of chunks when reading Ogg/Vorbis input data (16 KB).
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const INGEST_CHUNK_SIZE: usize = 16 * 1024;
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/// Channel capacity for async message passing between tasks.
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const CHANNEL_CAPACITY: usize = 8;
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/// Errors that can occur while decoding Ogg/Vorbis data.
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#[derive(thiserror::Error, Debug, Clone)]
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pub enum OggError {
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#[error("I/O error ({kind:?}): {message}")]
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Io {
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kind: io::ErrorKind,
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message: String,
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},
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#[error("Ogg/Vorbis decode error: {0}")]
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Decode(String),
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#[error("internal channel closed unexpectedly")]
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ChannelClosed,
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#[error("{role} task failed: {details}")]
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TaskJoin { role: &'static str, details: String },
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}
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impl From<io::Error> for OggError {
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fn from(err: io::Error) -> Self {
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OggError::Io {
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kind: err.kind(),
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message: err.to_string(),
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}
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}
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}
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impl From<header::HeaderReadError> for OggError {
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fn from(err: header::HeaderReadError) -> Self {
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OggError::Decode(err.to_string())
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}
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}
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impl From<audio::AudioReadError> for OggError {
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fn from(err: audio::AudioReadError) -> Self {
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OggError::Decode(err.to_string())
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}
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}
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impl From<String> for OggError {
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fn from(value: String) -> Self {
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OggError::Decode(value)
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}
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}
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/// An async stream that decodes Ogg/Vorbis audio into PCM samples.
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pub struct OggDecodedStream {
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info: StreamInfo,
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reader: ManagedAsyncReader<OggError>,
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}
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impl OggDecodedStream {
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/// Returns metadata about the decoded stream (sample rate, channels, etc.).
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pub fn info(&self) -> &StreamInfo {
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&self.info
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}
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/// Consumes the stream and returns its components.
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pub fn into_parts(self) -> (StreamInfo, ManagedAsyncReader<OggError>) {
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(self.info, self.reader)
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}
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/// Waits for the background decoding task to complete.
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pub async fn wait(self) -> Result<(), OggError> {
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self.reader.wait().await
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}
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}
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impl AsyncRead for OggDecodedStream {
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fn poll_read(
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mut self: Pin<&mut Self>,
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cx: &mut Context<'_>,
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buf: &mut ReadBuf<'_>,
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) -> Poll<io::Result<()>> {
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Pin::new(&mut self.reader).poll_read(cx, buf)
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}
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}
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/// Decodes an Ogg/Vorbis stream into PCM audio (16-bit little-endian, interleaved).
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pub async fn decode_ogg_vorbis_stream<R>(reader: R) -> Result<OggDecodedStream, OggError>
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where
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R: AsyncRead + Unpin + Send + 'static,
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{
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let (ingest_tx, ingest_rx) = mpsc::channel::<Result<Bytes, OggError>>(CHANNEL_CAPACITY);
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tokio::spawn(async move {
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let mut reader = tokio_io::BufReader::new(reader);
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let mut buf = vec![0u8; INGEST_CHUNK_SIZE];
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loop {
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match reader.read(&mut buf).await {
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Ok(0) => break,
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Ok(n) => {
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let chunk = Bytes::copy_from_slice(&buf[..n]);
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if ingest_tx.send(Ok(chunk)).await.is_err() {
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break;
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}
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}
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Err(err) => {
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let _ = ingest_tx.send(Err(OggError::from(err))).await;
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break;
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}
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}
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}
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});
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let (pcm_tx, mut pcm_rx) = mpsc::channel::<Result<Vec<u8>, OggError>>(CHANNEL_CAPACITY);
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let (pcm_reader, mut pcm_writer) = tokio_io::duplex(256 * 1024);
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let (info_tx, info_rx) = oneshot::channel::<Result<StreamInfo, OggError>>();
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let blocking_handle = tokio::task::spawn_blocking(move || -> Result<(), OggError> {
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let channel_reader = ChannelReader::<OggError>::new(ingest_rx);
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let mut packet_reader = StreamingPacketReader::new(channel_reader);
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// Read Vorbis headers
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let ident_packet = packet_reader
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.next_packet()?
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.ok_or_else(|| OggError::Decode("missing Vorbis identification header".into()))?;
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let ident_hdr = read_header_ident(&ident_packet)?;
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let comment_packet = packet_reader
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.next_packet()?
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.ok_or_else(|| OggError::Decode("missing Vorbis comment header".into()))?;
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let _comment_hdr: CommentHeader = read_header_comment(&comment_packet)?;
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let setup_packet = packet_reader
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.next_packet()?
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.ok_or_else(|| OggError::Decode("missing Vorbis setup header".into()))?;
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let setup_hdr = read_header_setup(&setup_packet, ident_hdr.audio_channels, (ident_hdr.blocksize_0, ident_hdr.blocksize_1))?;
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let info = StreamInfo {
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sample_rate: ident_hdr.audio_sample_rate,
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channels: ident_hdr.audio_channels,
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bits_per_sample: 16,
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total_samples: None,
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max_block_size: 1 << ident_hdr.blocksize_1,
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min_block_size: 1 << ident_hdr.blocksize_0,
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};
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if info_tx.send(Ok(info.clone())).is_err() {
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return Ok(());
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}
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let mut pcm_bytes = Vec::new();
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let mut produced_audio = false;
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let mut pwr = PreviousWindowRight::new();
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while let Some(packet) = packet_reader.next_packet()? {
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let decoded: InterleavedSamples<i16> =
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read_audio_packet_generic(&ident_hdr, &setup_hdr, &packet, &mut pwr)?;
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if decoded.samples.is_empty() {
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continue;
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}
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produced_audio = true;
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pcm_bytes.clear();
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pcm_bytes.reserve(decoded.samples.len() * 2);
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for sample in decoded.samples {
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pcm_bytes.extend_from_slice(&sample.to_le_bytes());
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}
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let chunk = std::mem::take(&mut pcm_bytes);
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if pcm_tx.blocking_send(Ok(chunk)).is_err() {
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break;
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}
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pcm_bytes = Vec::new();
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}
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if !produced_audio {
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let err = OggError::Decode("stream contained no decodable Vorbis packets".into());
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let _ = pcm_tx.blocking_send(Err(err.clone()));
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return Err(err);
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}
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Ok(())
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});
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let writer_handle = tokio::spawn(async move {
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while let Some(chunk_result) = pcm_rx.recv().await {
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let chunk = chunk_result?;
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if chunk.is_empty() {
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continue;
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}
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pcm_writer.write_all(&chunk).await.map_err(OggError::from)?;
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}
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pcm_writer.shutdown().await.map_err(OggError::from)?;
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match blocking_handle.await {
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Ok(res) => res,
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Err(err) => Err(OggError::TaskJoin {
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role: "ogg-decode",
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details: err.to_string(),
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}),
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}
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});
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let info = info_rx.await.map_err(|_| OggError::ChannelClosed)??;
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let reader = ManagedAsyncReader::new("ogg-decode-writer", pcm_reader, writer_handle);
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Ok(OggDecodedStream { info, reader })
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}
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/// Streaming packet reader that assembles Vorbis packets without seeking.
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struct StreamingPacketReader<E>
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where
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E: std::error::Error + std::fmt::Display,
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{
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reader: ChannelReader<E>,
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current_packet: Vec<u8>,
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queue: VecDeque<Vec<u8>>,
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finished: bool,
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eos_seen: bool,
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stream_serial: Option<u32>,
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}
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impl<E> StreamingPacketReader<E>
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where
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E: std::error::Error + std::fmt::Display,
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{
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fn new(reader: ChannelReader<E>) -> Self {
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Self {
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reader,
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current_packet: Vec::new(),
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queue: VecDeque::new(),
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finished: false,
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eos_seen: false,
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stream_serial: None,
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}
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}
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fn next_packet(&mut self) -> Result<Option<Vec<u8>>, OggError> {
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loop {
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if let Some(packet) = self.queue.pop_front() {
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return Ok(Some(packet));
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}
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if self.finished {
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return Ok(None);
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}
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self.read_page()?;
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}
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}
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fn read_page(&mut self) -> Result<(), OggError> {
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let mut header = [0u8; 27];
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if !read_exact_or_eof(&mut self.reader, &mut header)? {
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self.finished = true;
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return Ok(());
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}
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if &header[0..4] != b"OggS" {
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return Err(OggError::Decode("invalid Ogg capture pattern".into()));
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}
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if header[4] != 0 {
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return Err(OggError::Decode("unsupported Ogg version".into()));
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}
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let header_type = header[5];
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let bitstream_serial = u32::from_le_bytes([
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header[14], header[15], header[16], header[17],
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]);
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if let Some(serial) = self.stream_serial {
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if serial != bitstream_serial {
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return Err(OggError::Decode("multiple logical streams are not supported".into()));
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}
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} else {
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self.stream_serial = Some(bitstream_serial);
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}
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let page_segments = header[26] as usize;
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let mut segment_table = vec![0u8; page_segments];
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read_exact_checked(&mut self.reader, &mut segment_table)?;
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let data_len: usize = segment_table.iter().map(|&v| v as usize).sum();
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let mut data = vec![0u8; data_len];
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read_exact_checked(&mut self.reader, &mut data)?;
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if header_type & 0x01 != 0 && self.current_packet.is_empty() {
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return Err(OggError::Decode("unexpected continuation flag without existing packet".into()));
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}
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if header_type & 0x01 == 0 && !self.current_packet.is_empty() {
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return Err(OggError::Decode("dangling packet without continuation flag".into()));
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}
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let mut offset: usize = 0;
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for &seg_len in &segment_table {
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let len = seg_len as usize;
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let end = offset
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.checked_add(len)
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.ok_or_else(|| OggError::Decode("segment length overflow".into()))?;
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if end > data.len() {
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return Err(OggError::Decode("segment exceeds page data".into()));
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}
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self.current_packet.extend_from_slice(&data[offset..end]);
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offset = end;
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if seg_len < 255 {
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let packet = std::mem::take(&mut self.current_packet);
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self.queue.push_back(packet);
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}
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}
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if offset != data.len() {
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return Err(OggError::Decode("page data not fully consumed".into()));
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}
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if header_type & 0x04 != 0 {
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self.eos_seen = true;
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if self.current_packet.is_empty() {
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self.finished = true;
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}
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}
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Ok(())
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}
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}
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fn read_exact_or_eof<R: Read>(reader: &mut R, buf: &mut [u8]) -> io::Result<bool> {
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let mut read = 0;
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while read < buf.len() {
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match reader.read(&mut buf[read..])? {
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0 if read == 0 => return Ok(false),
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0 => return Err(io::Error::new(
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io::ErrorKind::UnexpectedEof,
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"unexpected EOF while reading",
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)),
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n => read += n,
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}
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}
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Ok(true)
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}
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fn read_exact_checked<R: Read>(reader: &mut R, buf: &mut [u8]) -> Result<(), OggError> {
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if !read_exact_or_eof(reader, buf)? {
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return Err(OggError::Decode("unexpected EOF in Ogg stream".into()));
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}
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Ok(())
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}
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