feat: Add audio track for hang-c library (#729)

Author: emilsas

rs/hang-c/src/lib.rs

@@ -2,19 +2,19 @@ use tokio::runtime::Runtime;
 use url::Url;
 
 use bytes::Bytes;
-use hang::catalog::{Video, VideoConfig, H264};
+use hang::catalog::{Audio, AudioConfig, Video, VideoConfig, AAC, H264};
 use hang::model::{Frame, Timestamp, TrackProducer};
 use hang::{Catalog, CatalogProducer};
 use moq_lite::{BroadcastProducer, Track};
 use std::ffi::CStr;
 use std::os::raw::c_char;
 use std::sync::atomic::{AtomicBool, Ordering};
-use std::sync::{Mutex, OnceLock};
+use std::sync::Mutex;
 use std::thread::JoinHandle;
 use std::{collections::HashMap, time::Duration};
 
-static IMPORT: OnceLock<Mutex<ImportJoy>> = OnceLock::new();
-static HANDLE: OnceLock<Mutex<JoinHandle<()>>> = OnceLock::new();
+static IMPORT: Mutex<Option<ImportJoy>> = Mutex::new(None);
+static HANDLE: Mutex<Option<JoinHandle<()>>> = Mutex::new(None);
 static RUNNING: AtomicBool = AtomicBool::new(false);
 
 /// # Safety
@@ -63,12 +63,22 @@ pub unsafe extern "C" fn hang_start_from_c(
 		});
 	});
 
-	let _ = HANDLE.set(Mutex::new(handle));
+	if let Ok(mut guard) = HANDLE.lock() {
+		*guard = Some(handle);
+	}
 }
 
 #[no_mangle]
 pub extern "C" fn hang_stop_from_c() {
 	RUNNING.store(false, Ordering::Relaxed);
+	if let Ok(mut guard) = HANDLE.lock() {
+		if let Some(handle) = guard.take() {
+			let _ = handle.join();
+		}
+	}
+	if let Ok(mut guard) = IMPORT.lock() {
+		*guard = None;
+	}
 }
 
 /// # Safety
@@ -83,14 +93,34 @@ pub unsafe extern "C" fn hang_write_video_packet_from_c(data: *const u8, size: u
 		return;
 	}
 
-	if let Some(import_mutex) = IMPORT.get() {
-		if let Ok(mut import) = import_mutex.lock() {
+	if let Ok(mut guard) = IMPORT.lock() {
+		if let Some(import) = guard.as_mut() {
 			// SAFETY: Caller of hang_write_video_packet_from_c guarantees data is valid
 			import.write_video_frame(data, size, keyframe > 0, dts);
 		}
 	}
 }
 
+/// # Safety
+///
+/// The caller must ensure that:
+/// - `data` points to a valid buffer of at least `size` bytes
+/// - The buffer remains valid for the duration of this function call
+#[no_mangle]
+pub unsafe extern "C" fn hang_write_audio_packet_from_c(data: *const u8, size: usize, dts: u64) {
+	// Validate pointer and size
+	if data.is_null() || size == 0 {
+		return;
+	}
+
+	if let Ok(mut guard) = IMPORT.lock() {
+		if let Some(import) = guard.as_mut() {
+			// SAFETY: Caller of hang_write_audio_packet_from_c guarantees data is valid
+			import.write_audio_frame(data, size, dts);
+		}
+	}
+}
+
 pub async fn client(url: Url, name: String) -> anyhow::Result<()> {
 	let broadcast = moq_lite::Broadcast::produce();
 	let config = moq_native::ClientConfig::default();
@@ -104,7 +134,9 @@ pub async fn client(url: Url, name: String) -> anyhow::Result<()> {
 
 	let mut import = ImportJoy::new(broadcast.producer);
 	import.init();
-	let _ = IMPORT.set(Mutex::new(import));
+	if let Ok(mut guard) = IMPORT.lock() {
+		*guard = Some(import);
+	}
 
 	origin.producer.publish_broadcast(&name, broadcast.consumer);
 
@@ -147,11 +179,12 @@ impl ImportJoy {
 	pub fn init(&mut self) {
 		// Produce the catalog
 		let mut video_renditions = HashMap::new();
+		let mut audio_renditions = HashMap::new();
 
 		let (track_name, config) = Self::init_video();
 		let track = Track {
 			name: track_name.clone(),
-			priority: 2,
+			priority: 1,
 		};
 		let track_produce = track.produce();
 		self.broadcast.insert_track(track_produce.consumer);
@@ -162,14 +195,33 @@ impl ImportJoy {
 		if !video_renditions.is_empty() {
 			let video = Video {
 				renditions: video_renditions,
-				priority: 2,
+				priority: 1,
 				display: None,
 				rotation: None,
 				flip: None,
 			};
 			self.catalog.set_video(Some(video));
 		}
 
+		let (track_name, config) = Self::init_audio();
+		let track = Track {
+			name: track_name.clone(),
+			priority: 2,
+		};
+		let track_produce = track.produce();
+		self.broadcast.insert_track(track_produce.consumer);
+		audio_renditions.insert(track_name, config);
+
+		self.tracks.insert(1, track_produce.producer.into());
+
+		if !audio_renditions.is_empty() {
+			let audio = Audio {
+				renditions: audio_renditions,
+				priority: 2,
+			};
+			self.catalog.set_audio(Some(audio));
+		}
+
 		self.catalog.publish();
 	}
 
@@ -197,6 +249,20 @@ impl ImportJoy {
 		(name, config)
 	}
 
+	pub fn init_audio() -> (String, AudioConfig) {
+		let name = String::from("audio1");
+
+		let config = AudioConfig {
+			codec: AAC { profile: 2 }.into(),
+			sample_rate: 48000,
+			channel_count: 2,
+			bitrate: Some(128000),
+			description: None,
+		};
+
+		(name, config)
+	}
+
 	/// # Safety
 	///
 	/// The caller must ensure that `data` points to a valid buffer of at least `size` bytes
@@ -225,4 +291,26 @@ impl ImportJoy {
 
 		track.write(frame);
 	}
+
+	/// # Safety
+	///
+	/// The caller must ensure that `data` points to a valid buffer of at least `size` bytes
+	pub unsafe fn write_audio_frame(&mut self, data: *const u8, size: usize, dts: u64) {
+		let Some(track) = self.tracks.get_mut(&1) else {
+			return;
+		};
+
+		// Use copy_from_slice to own the data, avoiding use-after-free when C caller frees the buffer
+		let payload = Bytes::copy_from_slice(std::slice::from_raw_parts(data, size));
+
+		let timestamp = Timestamp::from_micros(dts);
+
+		let frame = Frame {
+			timestamp,
+			keyframe: false,
+			payload,
+		};
+
+		track.write(frame);
+	}
 }