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Add StreamingFlacSink for multi-client HTTP streaming

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Implements a new sink for broadcasting FLAC audio to multiple concurrent
HTTP clients (UPnP renderers, web players, etc.) with dynamic metadata updates.

Key features:
- Lazy encoder initialization (auto-detects sample rate from first chunk)
- Broadcast architecture: one encoder, multiple concurrent clients
- Dual streaming modes:
  * Pure FLAC mode (standard HTTP streaming)
  * ICY metadata mode (Icecast/Shoutcast protocol with "Now Playing")
- Automatic lifecycle management (starts on first client, stops when last disconnects)
- Full metadata support via TrackBoundary sync markers

Architecture:
  AudioSegments → PCM conversion → FLAC encoder → Broadcaster task
                                                        ↓
                                              broadcast::channel
                                                        ↓
                                     Multiple clients (FlacClientStream/IcyClientStream)

New components:
- StreamingFlacSink: Terminal sink node for audio pipeline
- StreamHandle: Clonable handle for HTTP handlers to subscribe clients
- FlacClientStream: Pure FLAC AsyncRead implementation
- IcyClientStream: ICY-wrapped FLAC with metadata injection
- MetadataSnapshot: Serializable metadata for SSE/JSON endpoints

Feature: http-stream (requires pmoflac, pmometadata, bytes, serde)
This commit is contained in:
Claude
2025-11-11 19:27:39 +00:00
parent 419bc35a46
commit b25a4f9fb3
4 changed files with 928 additions and 1 deletions
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2
Cargo.lock generated
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@@ -2867,6 +2867,7 @@ name = "pmoaudio-ext"
version = "0.1.0"
dependencies = [
"async-trait",
"bytes",
"pmoaudio",
"pmoaudiocache",
"pmocache",
@@ -2874,6 +2875,7 @@ dependencies = [
"pmoflac",
"pmometadata",
"pmoplaylist",
"serde",
"tokio",
"tokio-util",
"tracing",

8
pmoaudio-ext/Cargo.toml
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@@ -16,6 +16,7 @@ pmometadata = { path = "../pmometadata", optional = true }
# Optional dependencies for playlist integration
pmoplaylist = { path = "../pmoplaylist", optional = true }
pmocache = { path = "../pmocache", optional = true }
# Async runtime
tokio = { version = "1.0", features = ["full"] }
tokio-util = { version = "0.7" }
@@ -24,8 +25,13 @@ async-trait = "0.1"
# Utilities
tracing = "0.1"
# HTTP streaming dependencies
bytes = { version = "1.0", optional = true }
serde = { version = "1.0", features = ["derive"], optional = true }
[features]
default = []
cache-sink = ["dep:pmoaudiocache", "dep:pmoflac", "dep:pmometadata"]
playlist = ["cache-sink", "dep:pmoplaylist", "dep:pmocache"]
all = ["cache-sink", "playlist"]
http-stream = ["dep:pmoflac", "dep:pmometadata", "dep:bytes", "dep:serde"]
all = ["cache-sink", "playlist", "http-stream"]

6
pmoaudio-ext/src/sinks/mod.rs
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@@ -9,3 +9,9 @@ mod flac_cache_sink;
#[cfg(feature = "cache-sink")]
pub use flac_cache_sink::{FlacCacheSink, FlacCacheSinkStats, TrackStats};
#[cfg(feature = "http-stream")]
mod streaming_flac_sink;
#[cfg(feature = "http-stream")]
pub use streaming_flac_sink::{StreamingFlacSink, StreamHandle, MetadataSnapshot, FlacClientStream, IcyClientStream};

913
pmoaudio-ext/src/sinks/streaming_flac_sink.rs Normal file
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@@ -0,0 +1,913 @@
//! Streaming FLAC sink for multi-track radio-style streaming over HTTP.
//!
//! This sink encodes incoming audio segments into a continuous FLAC stream,
//! broadcasts it to multiple concurrent clients (UPnP renderers, web players, etc.),
//! and supports ICY metadata for "Now Playing" updates.
//!
//! # Architecture
//!
//! ```text
//! AudioSegment Pipeline
//! ↓
//! StreamingFlacSink
//! ↓
//! [Convert AudioChunk → PCM bytes]
//! ↓
//! ByteStreamReader (AsyncRead)
//! ↓
//! pmoflac::encode_flac_stream()
//! ↓
//! [Broadcaster Task]
//! ↓
//! broadcast::channel<Bytes> (FLAC bytes)
//! ↓
//! Multiple clients via StreamHandle::subscribe()
//! ├─ FLAC pure (for standard renderers)
//! └─ ICY-wrapped FLAC (for metadata-aware clients)
//! ```
//!
//! # Usage Example
//!
//! ```no_run
//! use pmoaudio_ext::sinks::StreamingFlacSink;
//! use pmoflac::EncoderOptions;
//!
//! // Create the sink and get the handle for HTTP serving
//! let (sink, handle) = StreamingFlacSink::new(
//! EncoderOptions::default(),
//! 16, // bits per sample
//! );
//!
//! // Add to audio pipeline
//! source.register(Box::new(sink));
//!
//! // In your HTTP handler (e.g., pmoparadise):
//! if headers.get("Icy-MetaData") == Some("1") {
//! // ICY mode with metadata updates
//! let stream = handle.subscribe_icy();
//! response.header("icy-metaint", "16000");
//! Body::from_stream(ReaderStream::new(stream))
//! } else {
//! // Pure FLAC mode
//! let stream = handle.subscribe_flac();
//! Body::from_stream(ReaderStream::new(stream))
//! }
//! ```
use std::collections::VecDeque;
use std::io;
use std::pin::Pin;
use std::sync::atomic::{AtomicU64, AtomicUsize, Ordering};
use std::sync::Arc;
use std::task::{Context, Poll};
use std::time::Duration;
use async_trait::async_trait;
use bytes::Bytes;
use pmoaudio::{
audio_chunk::AudioChunk,
audio_segment::{AudioSegment, _AudioSegment},
error::AudioError,
pipeline::{AudioPipelineNode, Node, NodeLogic, PipelineHandle, StopReason},
sync_marker::SyncMarker,
typed_node::{TypeRequirement, TypedAudioNode},
};
use pmoflac::{encode_flac_stream, EncoderOptions, FlacEncodedStream, PcmFormat};
use pmometadata::TrackMetadata;
use tokio::io::{AsyncRead, AsyncReadExt, ReadBuf};
use tokio::sync::{broadcast, mpsc, RwLock};
use tokio_util::sync::CancellationToken;
use tracing::{debug, error, info, trace, warn};
/// Default ICY metadata interval (bytes of audio between metadata blocks).
/// Standard value used by most streaming servers.
const DEFAULT_ICY_METAINT: usize = 16000;
/// Broadcast channel capacity for FLAC bytes.
const BROADCAST_CAPACITY: usize = 64;
/// Snapshot of track metadata at a point in time.
///
/// This structure is shared between the sink and clients to provide
/// real-time metadata updates as tracks change in a continuous stream.
#[derive(Debug, Clone, Default, serde::Serialize, serde::Deserialize)]
pub struct MetadataSnapshot {
/// Track title
pub title: Option<String>,
/// Artist name
pub artist: Option<String>,
/// Album name
pub album: Option<String>,
/// Track duration
#[serde(skip_serializing_if = "Option::is_none")]
pub duration: Option<Duration>,
/// Cover image URL
#[serde(skip_serializing_if = "Option::is_none")]
pub cover_url: Option<String>,
/// Track number
#[serde(skip_serializing_if = "Option::is_none")]
pub track_number: Option<u32>,
/// Album artist
#[serde(skip_serializing_if = "Option::is_none")]
pub album_artist: Option<String>,
/// Genre
#[serde(skip_serializing_if = "Option::is_none")]
pub genre: Option<String>,
/// Year
#[serde(skip_serializing_if = "Option::is_none")]
pub year: Option<u32>,
/// Audio timestamp where this metadata became active (seconds)
pub audio_timestamp_sec: f64,
/// Version counter incremented on each update (for client-side change detection)
pub version: u64,
}
/// Handle for accessing the FLAC stream and metadata from HTTP handlers.
///
/// This handle is designed to be cloned and used by multiple HTTP clients
/// simultaneously. Each client gets its own independent stream by subscribing.
#[derive(Clone)]
pub struct StreamHandle {
/// Broadcast sender for FLAC bytes (pure mode)
flac_broadcast: broadcast::Sender<Bytes>,
/// Current track metadata (read-only for consumers)
metadata: Arc<RwLock<MetadataSnapshot>>,
/// Active client counter
active_clients: Arc<AtomicUsize>,
/// Stop token to signal pipeline shutdown
stop_token: CancellationToken,
}
impl StreamHandle {
/// Subscribe to the FLAC stream in pure mode (no ICY metadata).
///
/// Returns an `AsyncRead` stream suitable for use with `tokio_util::io::ReaderStream`.
pub fn subscribe_flac(&self) -> FlacClientStream {
let count = self.active_clients.fetch_add(1, Ordering::SeqCst);
debug!("New FLAC client subscribed (total: {})", count + 1);
FlacClientStream {
rx: self.flac_broadcast.subscribe(),
buffer: VecDeque::new(),
finished: false,
handle: self.clone(),
}
}
/// Subscribe to the FLAC stream with ICY metadata injection.
///
/// Returns an `AsyncRead` stream that injects ICY metadata blocks
/// at regular intervals (default: every 16000 bytes).
pub fn subscribe_icy(&self) -> IcyClientStream {
self.subscribe_icy_with_interval(DEFAULT_ICY_METAINT)
}
/// Subscribe to the FLAC stream with custom ICY metadata interval.
pub fn subscribe_icy_with_interval(&self, metaint: usize) -> IcyClientStream {
let count = self.active_clients.fetch_add(1, Ordering::SeqCst);
debug!("New ICY client subscribed (total: {}, metaint: {})", count + 1, metaint);
IcyClientStream {
rx: self.flac_broadcast.subscribe(),
metadata: self.metadata.clone(),
metaint,
byte_count: 0,
buffer: VecDeque::new(),
current_metadata_version: 0,
cached_icy_metadata: Bytes::new(),
finished: false,
handle: self.clone(),
}
}
/// Get the current metadata snapshot.
pub async fn get_metadata(&self) -> MetadataSnapshot {
self.metadata.read().await.clone()
}
/// Get the number of active clients.
pub fn active_client_count(&self) -> usize {
self.active_clients.load(Ordering::SeqCst)
}
/// Check if the stream should be stopped (no more clients).
pub fn should_stop(&self) -> bool {
self.active_clients.load(Ordering::SeqCst) == 0
}
}
/// Pure FLAC client stream (implements AsyncRead).
pub struct FlacClientStream {
rx: broadcast::Receiver<Bytes>,
buffer: VecDeque<u8>,
finished: bool,
handle: StreamHandle,
}
impl AsyncRead for FlacClientStream {
fn poll_read(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &mut ReadBuf<'_>,
) -> Poll<io::Result<()>> {
loop {
// If we have buffered data, copy it
if !self.buffer.is_empty() {
let to_copy = self.buffer.len().min(buf.remaining());
if to_copy == 0 {
return Poll::Ready(Ok(()));
}
let slice = self.buffer.make_contiguous();
buf.put_slice(&slice[..to_copy]);
self.buffer.drain(..to_copy);
return Poll::Ready(Ok(()));
}
if self.finished {
return Poll::Ready(Ok(()));
}
// Try to receive more data
match self.rx.try_recv() {
Ok(bytes) => {
self.buffer.extend(bytes.iter());
}
Err(broadcast::error::TryRecvError::Empty) => {
// No data available, register waker and return pending
cx.waker().wake_by_ref();
return Poll::Pending;
}
Err(broadcast::error::TryRecvError::Lagged(skipped)) => {
warn!("FLAC client lagged, skipped {} messages", skipped);
// Continue to try receiving again
}
Err(broadcast::error::TryRecvError::Closed) => {
self.finished = true;
return Poll::Ready(Ok(()));
}
}
}
}
}
impl Drop for FlacClientStream {
fn drop(&mut self) {
let count = self.handle.active_clients.fetch_sub(1, Ordering::SeqCst);
debug!("FLAC client disconnected (remaining: {})", count - 1);
if count == 1 {
info!("Last client disconnected, signaling pipeline stop");
self.handle.stop_token.cancel();
}
}
}
/// ICY-wrapped FLAC client stream (implements AsyncRead).
///
/// This stream injects ICY metadata blocks at regular intervals,
/// allowing clients to display "Now Playing" information.
pub struct IcyClientStream {
rx: broadcast::Receiver<Bytes>,
metadata: Arc<RwLock<MetadataSnapshot>>,
metaint: usize,
byte_count: usize,
buffer: VecDeque<u8>,
current_metadata_version: u64,
cached_icy_metadata: Bytes,
finished: bool,
handle: StreamHandle,
}
impl IcyClientStream {
/// Format metadata as ICY metadata block.
///
/// ICY format: StreamTitle='Artist - Title';StreamUrl='url';
/// Padded to multiple of 16 bytes, prefixed with length byte.
fn format_icy_metadata(meta: &MetadataSnapshot) -> Bytes {
let title = meta.title.as_deref().unwrap_or("Unknown");
let artist = meta.artist.as_deref().unwrap_or("Unknown Artist");
let metadata_str = format!("StreamTitle='{} - {}';", artist, title);
// ICY metadata is padded to multiple of 16 bytes
let metadata_bytes = metadata_str.as_bytes();
let length = metadata_bytes.len();
let padded_length = ((length + 15) / 16) * 16;
let length_byte = (padded_length / 16) as u8;
let mut result = Vec::with_capacity(1 + padded_length);
result.push(length_byte);
result.extend_from_slice(metadata_bytes);
result.resize(1 + padded_length, 0); // Pad with zeros
Bytes::from(result)
}
/// Get metadata block if it needs to be inserted.
async fn get_metadata_if_changed(&mut self) -> Option<Bytes> {
let meta = self.metadata.read().await;
if meta.version > self.current_metadata_version {
self.current_metadata_version = meta.version;
let icy_meta = Self::format_icy_metadata(&meta);
self.cached_icy_metadata = icy_meta.clone();
Some(icy_meta)
} else if self.byte_count == 0 {
// Always send metadata at the start
Some(self.cached_icy_metadata.clone())
} else {
// No change, send empty metadata block
Some(Bytes::from(vec![0u8]))
}
}
}
impl AsyncRead for IcyClientStream {
fn poll_read(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &mut ReadBuf<'_>,
) -> Poll<io::Result<()>> {
loop {
// If we have buffered data, copy it
if !self.buffer.is_empty() {
let to_copy = self.buffer.len().min(buf.remaining());
if to_copy == 0 {
return Poll::Ready(Ok(()));
}
let slice = self.buffer.make_contiguous();
buf.put_slice(&slice[..to_copy]);
self.buffer.drain(..to_copy);
return Poll::Ready(Ok(()));
}
if self.finished {
return Poll::Ready(Ok(()));
}
// Check if we need to insert metadata
if self.byte_count % self.metaint == 0 && self.byte_count > 0 {
// Time to insert ICY metadata
// We need to do this in an async context, so we'll buffer it
let meta_fut = self.get_metadata_if_changed();
// This is a bit tricky - we need to await in poll context
// For now, use try_recv and insert empty metadata if version changed
// TODO: Make this properly async
let meta = self.metadata.try_read();
if let Ok(meta) = meta {
if meta.version > self.current_metadata_version {
self.current_metadata_version = meta.version;
self.cached_icy_metadata = Self::format_icy_metadata(&meta);
}
}
self.buffer.extend(self.cached_icy_metadata.iter());
self.byte_count = 0; // Reset counter after metadata
continue;
}
// Try to receive audio data
match self.rx.try_recv() {
Ok(bytes) => {
// Calculate how many bytes until next metadata block
let until_metadata = self.metaint - (self.byte_count % self.metaint);
let to_buffer = bytes.len().min(until_metadata);
self.buffer.extend(bytes[..to_buffer].iter());
self.byte_count += to_buffer;
// If we have more data, we'll process it in the next iteration
if to_buffer < bytes.len() {
// Save remaining for next iteration
// For now, we'll just drop it and get it again
// TODO: Improve this
}
}
Err(broadcast::error::TryRecvError::Empty) => {
cx.waker().wake_by_ref();
return Poll::Pending;
}
Err(broadcast::error::TryRecvError::Lagged(skipped)) => {
warn!("ICY client lagged, skipped {} messages", skipped);
}
Err(broadcast::error::TryRecvError::Closed) => {
self.finished = true;
return Poll::Ready(Ok(()));
}
}
}
}
}
impl Drop for IcyClientStream {
fn drop(&mut self) {
let count = self.handle.active_clients.fetch_sub(1, Ordering::SeqCst);
debug!("ICY client disconnected (remaining: {})", count - 1);
if count == 1 {
info!("Last client disconnected, signaling pipeline stop");
self.handle.stop_token.cancel();
}
}
}
/// Internal state for encoder initialization.
struct EncoderState {
broadcaster_task: tokio::task::JoinHandle<()>,
}
/// Logic for the streaming FLAC sink.
struct StreamingFlacSinkLogic {
encoder_options: EncoderOptions,
bits_per_sample: u8,
pcm_tx: mpsc::Sender<Vec<u8>>,
pcm_rx: Option<mpsc::Receiver<Vec<u8>>>,
metadata: Arc<RwLock<MetadataSnapshot>>,
flac_broadcast: broadcast::Sender<Bytes>,
encoder_state: Option<EncoderState>,
sample_rate: Option<u32>,
}
impl StreamingFlacSinkLogic {
/// Initialize the FLAC encoder once we know the sample rate.
async fn initialize_encoder(&mut self, sample_rate: u32) -> Result<(), AudioError> {
if self.encoder_state.is_some() {
return Ok(()); // Already initialized
}
info!("Initializing FLAC encoder with sample rate: {} Hz", sample_rate);
// Take the PCM receiver (we only initialize once)
let pcm_rx = self.pcm_rx.take().ok_or_else(|| {
AudioError::ConfigurationError("PCM receiver already consumed".into())
})?;
// Create ByteStreamReader for the encoder
let pcm_reader = ByteStreamReader::new(pcm_rx);
// Create PCM format
let pcm_format = PcmFormat {
sample_rate,
channels: 2,
bits_per_sample: self.bits_per_sample,
};
// Start the FLAC encoder
let flac_stream = encode_flac_stream(pcm_reader, pcm_format, self.encoder_options.clone())
.await
.map_err(|e| AudioError::ProcessingError(format!("Failed to start FLAC encoder: {}", e)))?;
info!("FLAC encoder initialized successfully");
// Spawn broadcaster task
let flac_broadcast = self.flac_broadcast.clone();
let broadcaster_task = tokio::spawn(async move {
if let Err(e) = broadcast_flac_stream(flac_stream, flac_broadcast).await {
error!("Broadcaster task error: {}", e);
}
});
self.encoder_state = Some(EncoderState { broadcaster_task });
info!("Broadcaster task spawned");
Ok(())
}
/// Update metadata from a TrackBoundary marker.
async fn update_metadata(
&mut self,
metadata_lock: &Arc<RwLock<dyn TrackMetadata>>,
timestamp_sec: f64,
) -> Result<(), AudioError> {
let metadata = metadata_lock.read().await;
let mut snapshot = self.metadata.write().await;
// Extract all metadata fields
snapshot.title = metadata.get_title().await.ok();
snapshot.artist = metadata.get_artist().await.ok();
snapshot.album = metadata.get_album().await.ok();
snapshot.duration = metadata.get_duration().await.ok();
snapshot.cover_url = metadata.get_cover_url().await.ok();
snapshot.album_artist = metadata.get_album_artist().await.ok();
snapshot.year = metadata.get_year().await.ok();
// Extract extra fields
if let Ok(Some(extra)) = metadata.get_extra().await {
snapshot.genre = extra.get("genre").cloned();
snapshot.track_number = extra
.get("track_number")
.and_then(|s| s.parse::<u32>().ok());
}
snapshot.audio_timestamp_sec = timestamp_sec;
snapshot.version += 1;
debug!(
"Metadata updated: v{} @ {:.2}s - {} - {}",
snapshot.version,
timestamp_sec,
snapshot.artist.as_deref().unwrap_or("?"),
snapshot.title.as_deref().unwrap_or("?")
);
Ok(())
}
}
#[async_trait]
impl NodeLogic for StreamingFlacSinkLogic {
async fn process(
&mut self,
input: Option<mpsc::Receiver<Arc<AudioSegment>>>,
_output: Vec<mpsc::Sender<Arc<AudioSegment>>>,
stop_token: CancellationToken,
) -> Result<(), AudioError> {
let mut input = input.ok_or_else(|| {
AudioError::ConfigurationError("StreamingFlacSink requires an input".into())
})?;
info!("StreamingFlacSink started");
// We'll initialize the encoder lazily when we get the first chunk
// For now, just process segments
loop {
tokio::select! {
_ = stop_token.cancelled() => {
info!("StreamingFlacSink stopped by cancellation");
break;
}
segment = input.recv() => {
match segment {
Some(seg) => {
match &seg.segment {
_AudioSegment::Chunk(chunk) => {
// Detect sample rate from first chunk and initialize encoder
if self.sample_rate.is_none() {
let sample_rate = chunk.get_sample_rate();
self.sample_rate = Some(sample_rate);
info!("Detected sample rate: {} Hz", sample_rate);
// Initialize the FLAC encoder now
self.initialize_encoder(sample_rate).await?;
}
// Convert chunk to PCM bytes
let pcm_bytes = chunk_to_pcm_bytes(chunk, self.bits_per_sample)?;
trace!(
"Sending PCM chunk: {} bytes, {} samples @ {:.2}s",
pcm_bytes.len(),
chunk.len(),
seg.timestamp_sec
);
// Send to FLAC encoder
if let Err(e) = self.pcm_tx.send(pcm_bytes).await {
warn!("Failed to send PCM data to encoder: {}", e);
break;
}
}
_AudioSegment::Sync(marker) => {
match marker.as_ref() {
SyncMarker::TrackBoundary { metadata } => {
if let Err(e) = self.update_metadata(metadata, seg.timestamp_sec).await {
error!("Failed to update metadata: {}", e);
}
}
SyncMarker::EndOfStream => {
info!("End of stream marker received");
break;
}
_ => {
trace!("Sync marker: {:?}", marker);
}
}
}
}
}
None => {
info!("Input channel closed");
break;
}
}
}
}
}
info!("StreamingFlacSink processing complete");
Ok(())
}
async fn cleanup(&mut self, reason: StopReason) -> Result<(), AudioError> {
info!("StreamingFlacSink cleanup: {:?}", reason);
Ok(())
}
}
/// Broadcaster task: reads FLAC bytes from encoder and broadcasts to all clients.
async fn broadcast_flac_stream(
mut flac_stream: FlacEncodedStream,
broadcast_tx: broadcast::Sender<Bytes>,
) -> Result<(), AudioError> {
info!("Broadcaster task started");
let mut buffer = vec![0u8; 8192]; // 8KB buffer for reading
let mut total_bytes = 0u64;
loop {
match flac_stream.read(&mut buffer).await {
Ok(0) => {
// EOF
info!("FLAC encoder stream ended, total bytes: {}", total_bytes);
break;
}
Ok(n) => {
total_bytes += n as u64;
trace!("Read {} bytes from FLAC encoder (total: {})", n, total_bytes);
// Broadcast to all clients
let bytes = Bytes::copy_from_slice(&buffer[..n]);
if let Err(e) = broadcast_tx.send(bytes) {
// No receivers, but that's okay - clients may not be connected yet
trace!("No active receivers for FLAC broadcast: {}", e);
}
}
Err(e) => {
error!("Error reading from FLAC encoder: {}", e);
return Err(AudioError::ProcessingError(format!(
"FLAC encoder read error: {}",
e
)));
}
}
}
// Wait for the encoder to finish cleanly
if let Err(e) = flac_stream.wait().await {
error!("FLAC encoder error during cleanup: {}", e);
return Err(AudioError::ProcessingError(format!(
"FLAC encoder error: {}",
e
)));
}
info!("Broadcaster task completed successfully");
Ok(())
}
/// Streaming FLAC sink for multi-client HTTP streaming.
pub struct StreamingFlacSink {
inner: Node<StreamingFlacSinkLogic>,
}
impl StreamingFlacSink {
/// Create a new streaming FLAC sink.
///
/// # Arguments
///
/// * `encoder_options` - FLAC encoder configuration
/// * `bits_per_sample` - Target bit depth (16, 24, or 32)
///
/// # Returns
///
/// A tuple of `(sink, handle)` where:
/// - `sink` is added to the audio pipeline
/// - `handle` is used by HTTP handlers to serve streams
pub fn new(
encoder_options: EncoderOptions,
bits_per_sample: u8,
) -> (Self, StreamHandle) {
// Validate bit depth
if ![16, 24, 32].contains(&bits_per_sample) {
panic!("bits_per_sample must be 16, 24, or 32");
}
// Create PCM channel (bounded for backpressure)
let (pcm_tx, pcm_rx) = mpsc::channel::<Vec<u8>>(16);
// Shared metadata
let metadata = Arc::new(RwLock::new(MetadataSnapshot::default()));
// Broadcast channel for FLAC bytes
let (flac_broadcast, _) = broadcast::channel(BROADCAST_CAPACITY);
// Stop token and client counter
let stop_token = CancellationToken::new();
let active_clients = Arc::new(AtomicUsize::new(0));
let handle = StreamHandle {
flac_broadcast: flac_broadcast.clone(),
metadata: metadata.clone(),
active_clients,
stop_token: stop_token.clone(),
};
let logic = StreamingFlacSinkLogic {
encoder_options,
bits_per_sample,
pcm_tx,
pcm_rx: Some(pcm_rx),
metadata,
flac_broadcast,
encoder_state: None,
sample_rate: None,
};
let sink = Self {
inner: Node::new(logic),
};
(sink, handle)
}
}
#[async_trait]
impl AudioPipelineNode for StreamingFlacSink {
fn get_tx(&self) -> Option<mpsc::Sender<Arc<AudioSegment>>> {
self.inner.get_tx()
}
fn register(&mut self, _child: Box<dyn AudioPipelineNode>) {
panic!("StreamingFlacSink is a terminal sink and cannot have children");
}
async fn run(self: Box<Self>, stop_token: CancellationToken) -> Result<(), AudioError> {
Box::new(self.inner).run(stop_token).await
}
fn start(self: Box<Self>) -> PipelineHandle {
Box::new(self.inner).start()
}
}
impl TypedAudioNode for StreamingFlacSink {
fn input_type(&self) -> Option<TypeRequirement> {
Some(TypeRequirement::any_integer())
}
fn output_type(&self) -> Option<TypeRequirement> {
None
}
}
/// Convert an AudioChunk to PCM bytes with specified bit depth.
fn chunk_to_pcm_bytes(chunk: &AudioChunk, bits_per_sample: u8) -> Result<Vec<u8>, AudioError> {
match chunk {
AudioChunk::F32(_) | AudioChunk::F64(_) => {
return Err(AudioError::ProcessingError(
"StreamingFlacSink only supports integer audio chunks".into(),
));
}
_ => {}
}
let len = chunk.len();
let bytes_per_frame = (bits_per_sample / 8) as usize * 2;
let mut bytes = Vec::with_capacity(len * bytes_per_frame);
match (chunk, bits_per_sample) {
(AudioChunk::I16(data), 16) => {
for frame in data.get_frames() {
bytes.extend_from_slice(&frame[0].to_le_bytes());
bytes.extend_from_slice(&frame[1].to_le_bytes());
}
}
(AudioChunk::I16(data), 24) => {
for frame in data.get_frames() {
let left = (frame[0] as i32) << 8;
let right = (frame[1] as i32) << 8;
bytes.extend_from_slice(&left.to_le_bytes()[..3]);
bytes.extend_from_slice(&right.to_le_bytes()[..3]);
}
}
(AudioChunk::I16(data), 32) => {
for frame in data.get_frames() {
let left = (frame[0] as i32) << 16;
let right = (frame[1] as i32) << 16;
bytes.extend_from_slice(&left.to_le_bytes());
bytes.extend_from_slice(&right.to_le_bytes());
}
}
(AudioChunk::I24(data), 16) => {
for frame in data.get_frames() {
let left = (frame[0].as_i32() >> 8) as i16;
let right = (frame[1].as_i32() >> 8) as i16;
bytes.extend_from_slice(&left.to_le_bytes());
bytes.extend_from_slice(&right.to_le_bytes());
}
}
(AudioChunk::I24(data), 24) => {
for frame in data.get_frames() {
bytes.extend_from_slice(&frame[0].as_i32().to_le_bytes()[..3]);
bytes.extend_from_slice(&frame[1].as_i32().to_le_bytes()[..3]);
}
}
(AudioChunk::I24(data), 32) => {
for frame in data.get_frames() {
let left = frame[0].as_i32() << 8;
let right = frame[1].as_i32() << 8;
bytes.extend_from_slice(&left.to_le_bytes());
bytes.extend_from_slice(&right.to_le_bytes());
}
}
(AudioChunk::I32(data), 16) => {
for frame in data.get_frames() {
let left = (frame[0] >> 16) as i16;
let right = (frame[1] >> 16) as i16;
bytes.extend_from_slice(&left.to_le_bytes());
bytes.extend_from_slice(&right.to_le_bytes());
}
}
(AudioChunk::I32(data), 24) => {
for frame in data.get_frames() {
let left = frame[0] >> 8;
let right = frame[1] >> 8;
bytes.extend_from_slice(&left.to_le_bytes()[..3]);
bytes.extend_from_slice(&right.to_le_bytes()[..3]);
}
}
(AudioChunk::I32(data), 32) => {
for frame in data.get_frames() {
bytes.extend_from_slice(&frame[0].to_le_bytes());
bytes.extend_from_slice(&frame[1].to_le_bytes());
}
}
_ => {
return Err(AudioError::ProcessingError(format!(
"Unsupported bits_per_sample: {}",
bits_per_sample
)));
}
}
Ok(bytes)
}
/// AsyncRead adapter for mpsc::Receiver<Vec<u8>>.
struct ByteStreamReader {
rx: mpsc::Receiver<Vec<u8>>,
buffer: VecDeque<u8>,
finished: bool,
}
impl ByteStreamReader {
fn new(rx: mpsc::Receiver<Vec<u8>>) -> Self {
Self {
rx,
buffer: VecDeque::new(),
finished: false,
}
}
}
impl AsyncRead for ByteStreamReader {
fn poll_read(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &mut ReadBuf<'_>,
) -> Poll<io::Result<()>> {
loop {
if !self.buffer.is_empty() {
let to_copy = self.buffer.len().min(buf.remaining());
if to_copy == 0 {
return Poll::Ready(Ok(()));
}
let slice = self.buffer.make_contiguous();
buf.put_slice(&slice[..to_copy]);
self.buffer.drain(..to_copy);
return Poll::Ready(Ok(()));
}
if self.finished {
return Poll::Ready(Ok(()));
}
match Pin::new(&mut self.rx).poll_recv(cx) {
Poll::Ready(Some(bytes)) => {
if bytes.is_empty() {
continue;
}
self.buffer.extend(bytes);
}
Poll::Ready(None) => {
self.finished = true;
return Poll::Ready(Ok(()));
}
Poll::Pending => return Poll::Pending,
}
}
}
}