fix:(audioworklet): bug when Wasm memory resizes and avoid JS allocations (#1050)

kettle11 · web-flow · commit 44d6a76d9c50 · 2025-12-07T15:52:17.000+01:00
diff --git a/.github/workflows/platforms.yml b/.github/workflows/platforms.yml
@@ -264,7 +264,7 @@ jobs:
             build-wasm-beep: true
 
           - target: wasm32-unknown-unknown
-            args: --features=web_audio_worklet
+            args: --features=audioworklet
             build-worklet-beep: true
             rustflags: -C target-feature=+atomics,+bulk-memory,+mutable-globals
 
@@ -306,9 +306,9 @@ jobs:
         working-directory: ./examples/wasm-beep
         run: cargo build --target ${{ matrix.target }}
 
-      - name: Build web-audio-worklet-beep example
+      - name: Build audioworklet-beep example
         if: matrix.build-worklet-beep
-        working-directory: ./examples/web-audio-worklet-beep
+        working-directory: ./examples/audioworklet-beep
         env:
           RUSTFLAGS: ${{ matrix.rustflags }}
         run: cargo +nightly build --target ${{ matrix.target }} -Z build-std=std,panic_abort
diff --git a/.github/workflows/quality.yml b/.github/workflows/quality.yml
@@ -141,7 +141,7 @@ jobs:
         with:
           key: clippy-wasm32-worklet
 
-      - name: Run clippy (web_audio_worklet)
+      - name: Run clippy (audioworklet)
         env:
           RUSTFLAGS: -C target-feature=+atomics,+bulk-memory,+mutable-globals
-        run: cargo +nightly clippy --all --target wasm32-unknown-unknown --features web_audio_worklet -Z build-std=std,panic_abort -- -D warnings
+        run: cargo +nightly clippy --all --target wasm32-unknown-unknown --features audioworklet -Z build-std=std,panic_abort -- -D warnings
diff --git a/.gitignore b/.gitignore
@@ -5,5 +5,5 @@
 recorded.wav
 rls*.log
 /.direnv
-!/examples/web-audio-worklet-beep/.cargo/
+!/examples/audioworklet-beep/.cargo/
 
diff --git a/Cargo.toml b/Cargo.toml
@@ -16,7 +16,7 @@ asio = [
 ] # Only available on Windows. See README for setup instructions.
 
 # Only available on web when atomics are enabled. See README for what it does.
-web_audio_worklet = [
+audioworklet = [
     "dep:wasm-bindgen-futures",
     "web-sys/Blob",
     "web-sys/BlobPropertyBag",
diff --git a/README.md b/README.md
@@ -37,9 +37,9 @@ Some audio backends are optional and will only be compiled with a [feature flag]
 
 - JACK (on Linux): `jack`
 - ASIO (on Windows): `asio`
-- AudioWorklet (on Web): `web_audio_worklet`
+- AudioWorklet (on Web): `audioworklet`
 
-For AudioWorklet backend usage see the README for the `web-audio-worklet-beep` example.
+For AudioWorklet backend usage see the README for the `audioworklet-beep` example.
 
 ## ASIO on Windows
 
diff --git a/examples/audioworklet-beep/.cargo/config.toml b/examples/audioworklet-beep/.cargo/config.toml
diff --git a/examples/audioworklet-beep/.gitignore b/examples/audioworklet-beep/.gitignore
diff --git a/examples/audioworklet-beep/Cargo.toml b/examples/audioworklet-beep/Cargo.toml
@@ -1,5 +1,5 @@
 [package]
-name = "web-audio-worklet-beep"
+name = "audioworklet-beep"
 description = "cpal beep example for WebAssembly on an AudioWorklet"
 version = "0.1.0"
 edition = "2018"
@@ -18,7 +18,7 @@ lto = true
 #default = ["wee_alloc"]
 
 [dependencies]
-cpal = { path = "../..", features = ["wasm-bindgen", "web_audio_worklet"] }
+cpal = { path = "../..", features = ["wasm-bindgen", "audioworklet"] }
 # `gloo` is a utility crate which improves ergonomics over direct `web-sys` usage.
 gloo = "0.11.0"
 # The `wasm-bindgen` crate provides the bare minimum functionality needed
diff --git a/examples/audioworklet-beep/README.md b/examples/audioworklet-beep/README.md
diff --git a/examples/audioworklet-beep/Trunk.toml b/examples/audioworklet-beep/Trunk.toml
diff --git a/examples/audioworklet-beep/index.html b/examples/audioworklet-beep/index.html
diff --git a/examples/audioworklet-beep/src/lib.rs b/examples/audioworklet-beep/src/lib.rs
@@ -48,8 +48,8 @@ pub fn main_js() -> Result<(), JsValue> {
 }
 
 fn beep() -> Stream {
-    let host = cpal::host_from_id(cpal::HostId::WebAudioWorklet)
-        .expect("WebAudioWorklet host not available");
+    let host =
+        cpal::host_from_id(cpal::HostId::AudioWorklet).expect("AudioWorklet host not available");
 
     let device = host
         .default_output_device()
diff --git a/src/host/audioworklet/dependent_module.rs b/src/host/audioworklet/dependent_module.rs
@@ -57,6 +57,6 @@ pub fn on_the_fly(code: &str) -> Result<String, JsValue> {
 #[macro_export]
 macro_rules! dependent_module {
     ($file_name:expr) => {
-        $crate::host::web_audio_worklet::dependent_module::on_the_fly(include_str!($file_name))
+        $crate::host::audioworklet::dependent_module::on_the_fly(include_str!($file_name))
     };
 }
diff --git a/src/host/audioworklet/mod.rs b/src/host/audioworklet/mod.rs
@@ -102,7 +102,7 @@ impl DeviceTrait for Device {
     #[inline]
     fn id(&self) -> Result<DeviceId, DeviceIdError> {
         Ok(DeviceId(
-            crate::platform::HostId::WebAudioWorklet,
+            crate::platform::HostId::AudioWorklet,
             "default".to_string(),
         ))
     }
diff --git a/src/host/audioworklet/worklet.js b/src/host/audioworklet/worklet.js
@@ -0,0 +1,49 @@
+registerProcessor("CpalProcessor", class WasmProcessor extends AudioWorkletProcessor {
+    constructor(options) {
+        super();
+        let [module, memory, handle] = options.processorOptions;
+        bindgen.initSync({ module, memory });
+        this.processor = bindgen.WasmAudioProcessor.unpack(handle);
+        this.memory = memory;
+        this.wasm_memory = new Float32Array(memory.buffer);
+    }
+
+    process(inputs, outputs) {
+        // Check if memory grew and update view
+        if (this.wasm_memory.buffer !== this.memory.buffer) {
+            this.wasm_memory = new Float32Array(this.memory.buffer);
+        }
+
+        const channels = outputs[0];
+        const channels_count = channels.length;
+        const frame_size = channels[0].length;
+        const interleaved_ptr = this.processor.process(
+            channels_count,
+            frame_size,
+            sampleRate,
+            currentTime
+        );
+
+        const interleaved_start = interleaved_ptr / 4; // Convert byte offset to f32 index
+        const interleaved = this.wasm_memory;
+
+        const total_samples = frame_size * channels_count;
+        if (interleaved_start + total_samples > this.wasm_memory.length) {
+            console.error("CpalProcessor: Audio buffer out of bounds! Ptr:", interleaved_ptr, "Len:", total_samples);
+            return false; // Safely stop the node
+        }
+
+        // Deinterleave: read strided from Wasm, write sequential to output
+        for (let ch = 0; ch < channels_count; ch++) {
+            const channel = channels[ch];
+            let read_pos = interleaved_start + ch;
+
+            for (let i = 0; i < frame_size; i++) {
+                channel[i] = interleaved[read_pos];
+                read_pos += channels_count;
+            }
+        }
+
+        return true;
+    }
+});
diff --git a/src/host/mod.rs b/src/host/mod.rs
@@ -9,6 +9,13 @@ pub(crate) mod aaudio;
 pub(crate) mod alsa;
 #[cfg(all(windows, feature = "asio"))]
 pub(crate) mod asio;
+#[cfg(all(
+    target_arch = "wasm32",
+    feature = "wasm-bindgen",
+    feature = "audioworklet",
+    target_feature = "atomics"
+))]
+pub(crate) mod audioworklet;
 #[cfg(any(target_os = "macos", target_os = "ios"))]
 pub(crate) mod coreaudio;
 #[cfg(target_os = "emscripten")]
@@ -25,13 +32,6 @@ pub(crate) mod emscripten;
 pub(crate) mod jack;
 #[cfg(windows)]
 pub(crate) mod wasapi;
-#[cfg(all(
-    target_arch = "wasm32",
-    feature = "wasm-bindgen",
-    feature = "web_audio_worklet",
-    target_feature = "atomics"
-))]
-pub(crate) mod web_audio_worklet;
 #[cfg(all(target_arch = "wasm32", feature = "wasm-bindgen"))]
 pub(crate) mod webaudio;
 
diff --git a/src/host/web_audio_worklet/worklet.js b/src/host/web_audio_worklet/worklet.js
diff --git a/src/platform/mod.rs b/src/platform/mod.rs
@@ -100,7 +100,7 @@ macro_rules! impl_platform_host {
         /// - `"null"` - Null host
         /// - `"wasapi"` - Windows Audio Session API
         /// - `"webaudio"` - Web Audio API
-        /// - `"webaudioworklet"` - Web Audio Worklet
+        /// - `"audioworklet"` - Audio Worklet
         ///
         /// # Cross-Platform Example
         ///
@@ -734,12 +734,12 @@ mod platform_impl {
 mod platform_impl {
     pub use crate::host::webaudio::Host as WebAudioHost;
 
-    #[cfg(feature = "web_audio_worklet")]
-    pub use crate::host::web_audio_worklet::Host as WebAudioWorkletHost;
+    #[cfg(feature = "audioworklet")]
+    pub use crate::host::audioworklet::Host as AudioWorkletHost;
 
     impl_platform_host!(
         WebAudio => WebAudioHost,
-        #[cfg(feature = "web_audio_worklet")] WebAudioWorklet => WebAudioWorkletHost,
+        #[cfg(feature = "audioworklet")] AudioWorklet => AudioWorkletHost,
         #[cfg(feature = "custom")] Custom => super::CustomHost
     );
 
