Merge pull request #497 from orottier/feature/audio_process_event_owned

Change ScriptProcessorNode::onaudioprocess API - use owned buffer value

Author: orottier

examples/script_processor.rs

@@ -28,7 +28,7 @@ fn main() {
     });
 
     let node = context.create_script_processor(512, 1, 1);
-    node.set_onaudioprocess(|e| {
+    node.set_onaudioprocess(|mut e| {
         let mut rng = rand::thread_rng();
         e.output_buffer
             .get_channel_data_mut(0)

src/context/mod.rs

@@ -88,9 +88,8 @@ impl From<u8> for AudioContextState {
 /// Only when implementing the AudioNode trait manually, this struct is of any concern.
 ///
 /// This object allows for communication with the render thread and dynamic lifetime management.
-//
-// The only way to construct this object is by calling [`BaseAudioContext::register`]
-#[derive(Clone)]
+// The only way to construct this object is by calling [`BaseAudioContext::register`].
+// This struct should not derive Clone because of the Drop handler.
 pub struct AudioContextRegistration {
     /// the audio context in which nodes and connections lives
     context: ConcreteBaseAudioContext,

src/events.rs

@@ -1,3 +1,4 @@
+use crate::context::ConcreteBaseAudioContext;
 use crate::context::{AudioContextState, AudioNodeId};
 use crate::{AudioBuffer, AudioRenderCapacityEvent};
 
@@ -52,6 +53,19 @@ pub struct AudioProcessingEvent {
     /// The time when the audio will be played in the same time coordinate system as the
     /// AudioContext's currentTime.
     pub playback_time: f64,
+    pub(crate) registration: Option<(ConcreteBaseAudioContext, AudioNodeId)>,
+}
+
+impl Drop for AudioProcessingEvent {
+    fn drop(&mut self) {
+        if let Some((context, id)) = self.registration.take() {
+            let wrapped = crate::message::ControlMessage::NodeMessage {
+                id,
+                msg: llq::Node::new(Box::new(self.output_buffer.clone())),
+            };
+            context.send_control_msg(wrapped);
+        }
+    }
 }
 
 /// The OfflineAudioCompletionEvent Event interface

src/node/script_processor.rs

@@ -137,20 +137,26 @@ impl ScriptProcessorNode {
     /// the inputBuffer attribute. The audio data which is the result of the processing (or the
     /// synthesized data if there are no inputs) is then placed into the outputBuffer.
     ///
+    /// The output buffer is shipped back to the render thread when the AudioProcessingEvent goes
+    /// out of scope, so be sure not to store it somewhere.
+    ///
     /// Only a single event handler is active at any time. Calling this method multiple times will
     /// override the previous event handler.
-    pub fn set_onaudioprocess<F: FnMut(&mut AudioProcessingEvent) + Send + 'static>(
+    pub fn set_onaudioprocess<F: FnMut(AudioProcessingEvent) + Send + 'static>(
         &self,
         mut callback: F,
     ) {
-        let registration = self.registration.clone();
+        // We need these fields to ship the output buffer to the render thread
+        let base = self.registration().context().clone();
+        let id = self.registration().id();
+
         let callback = move |v| {
             let mut payload = match v {
                 EventPayload::AudioProcessing(v) => v,
                 _ => unreachable!(),
             };
-            callback(&mut payload);
-            registration.post_message(payload.output_buffer);
+            payload.registration = Some((base.clone(), id));
+            callback(payload);
         };
 
         self.context().set_event_handler(
@@ -305,7 +311,7 @@ mod tests {
 
         let node = context.create_script_processor(BUFFER_SIZE, 0, 1);
         node.connect(&context.destination());
-        node.set_onaudioprocess(|e| {
+        node.set_onaudioprocess(|mut e| {
             e.output_buffer.get_channel_data_mut(0).fill(1.); // set all samples to 1.
         });
 
@@ -336,7 +342,7 @@ mod tests {
         // 2 input channels, 2 output channels
         let node = context.create_script_processor(BUFFER_SIZE, 2, 2);
         node.connect(&context.destination());
-        node.set_onaudioprocess(|e| {
+        node.set_onaudioprocess(|mut e| {
             // left output buffer is left input * 2
             e.output_buffer
                 .get_channel_data_mut(0)

src/render/processor.rs

@@ -68,6 +68,7 @@ impl AudioWorkletGlobalScope {
             input_buffer,
             output_buffer,
             playback_time,
+            registration: None,
         };
         let dispatch = EventDispatch::audio_processing(self.node_id.get(), event);
         let _ = self.event_sender.try_send(dispatch);