At online AudioContext creation, preload the HRTF database

Author: orottier

src/context/concrete_base.rs

@@ -193,22 +193,28 @@ impl ConcreteBaseAudioContext {
             };
 
             (listener_params, destination_channel_config)
-        }; // nodes will drop now, so base.inner has no copies anymore
+        }; // Nodes will drop now, so base.inner has no copies anymore
 
         let mut base = base;
         let inner_mut = Arc::get_mut(&mut base.inner).unwrap();
         inner_mut.listener_params = Some(listener_params);
         inner_mut.destination_channel_config = destination_channel_config;
 
-        // validate if the hardcoded node IDs line up
+        // Validate if the hardcoded node IDs line up
         debug_assert_eq!(
             base.inner.node_id_inc.load(Ordering::Relaxed),
             LISTENER_PARAM_IDS.end,
         );
 
-        // (?) only for online context
+        // For an online AudioContext, pre-create the HRTF-database for panner nodes
+        if !offline {
+            crate::node::load_hrtf_processor(sample_rate as u32);
+        }
+
+        // Boot the event loop thread that handles the events spawned by the render thread
+        // (we don't do this for offline rendering because it makes little sense, the graph cannot
+        // be mutated once rendering has started anyway)
         if let Some(event_channel) = event_recv {
-            // init event loop
             event_loop.run(event_channel);
         }
 

src/node/panner.rs

@@ -20,7 +20,7 @@ use super::{
 /// The included data contains the impulse responses at 44100 Hertz, so it needs to be resampled
 /// for other values (which can easily take 100s of milliseconds). Therefore cache the result (per
 /// sample rate) in a global variable and clone it every time a new panner is created.
-fn load_hrtf_processor(sample_rate: u32) -> (HrtfProcessor, usize) {
+pub(crate) fn load_hrtf_processor(sample_rate: u32) -> (HrtfProcessor, usize) {
     static INSTANCE: OnceLock<Mutex<HashMap<u32, (HrtfProcessor, usize)>>> = OnceLock::new();
     let cache = INSTANCE.get_or_init(|| Mutex::new(HashMap::new()));
     let mut guard = cache.lock().unwrap();