Add support for multichannel decoded audio

components/script/dom/audiobuffer.rs

@@ -64,7 +64,7 @@ impl AudioBuffer {
         number_of_channels: u32,
         length: u32,
         sample_rate: f32,
-        initial_data: Option<&[f32]>,
+        initial_data: Option<&[Vec<f32>]>,
     ) -> DomRoot<AudioBuffer> {
         let buffer = AudioBuffer::new_inherited(number_of_channels, length, sample_rate);
         let buffer = reflect_dom_object(Box::new(buffer), global, AudioBufferBinding::Wrap);
@@ -93,20 +93,19 @@ impl AudioBuffer {
     }
 
     #[allow(unsafe_code)]
-    pub fn set_channels(&self, initial_data: Option<&[f32]>) {
+    pub fn set_channels(&self, initial_data: Option<&[Vec<f32>]>) {
         let global = self.global();
         let cx = global.get_cx();
         let _ac = JSAutoCompartment::new(cx, global.reflector().get_jsobject().get());
         let chans = self.js_channels.borrow_mut();
         for channel in 0..self.number_of_channels {
             rooted!(in (cx) let mut array = ptr::null_mut::<JSObject>());
-            let offset = (channel * self.length) as usize;
             match initial_data {
                 Some(data) => {
                     let _ = unsafe {
                         Float32Array::create(
                             cx,
-                            CreateWith::Slice(&data[offset..offset + (self.length as usize) - 1]),
+                            CreateWith::Slice(data[channel as usize].as_slice()),
                             array.handle_mut(),
                         )
                     };

components/script/dom/baseaudiocontext.rs

@@ -405,6 +405,7 @@ impl BaseAudioContextMethods for BaseAudioContext {
             let audio_data = audio_data.to_vec();
             let decoded_audio = Arc::new(Mutex::new(Vec::new()));
             let decoded_audio_ = decoded_audio.clone();
+            let decoded_audio__ = decoded_audio.clone();
             let this = Trusted::new(self);
             let this_ = this.clone();
             let task_source = window.dom_manipulation_task_source();
@@ -412,15 +413,30 @@ impl BaseAudioContextMethods for BaseAudioContext {
             let canceller = window.task_canceller(TaskSourceName::DOMManipulation);
             let canceller_ = window.task_canceller(TaskSourceName::DOMManipulation);
             let callbacks = AudioDecoderCallbacks::new()
+                .ready(move |channel_count| {
+                    decoded_audio
+                        .lock()
+                        .unwrap()
+                        .resize(channel_count as usize, Vec::new());
+                })
+                .progress(move |buffer, channel| {
+                    let mut decoded_audio = decoded_audio_.lock().unwrap();
+                    decoded_audio[(channel - 1) as usize].extend_from_slice((*buffer).as_ref());
+                })
                 .eos(move || {
                     let _ = task_source.queue_with_canceller(
                         task!(audio_decode_eos: move || {
                             let this = this.root();
-                            let decoded_audio = decoded_audio.lock().unwrap();
+                            let decoded_audio = decoded_audio__.lock().unwrap();
+                            let length = if decoded_audio.len() >= 1 {
+                                decoded_audio[0].len()
+                            } else {
+                                0
+                            };
                             let buffer = AudioBuffer::new(
                                 &this.global().as_window(),
-                                1, // XXX servo-media should provide this info
-                                decoded_audio.len() as u32,
+                                decoded_audio.len() as u32 /* number of channels */,
+                                length as u32,
                                 this.sample_rate,
                                 Some(decoded_audio.as_slice()));
                             let mut resolvers = this.decode_resolvers.borrow_mut();
@@ -451,12 +467,6 @@ impl BaseAudioContextMethods for BaseAudioContext {
                         &canceller_,
                     );
                 })
-                .progress(move |buffer| {
-                    decoded_audio_
-                        .lock()
-                        .unwrap()
-                        .extend_from_slice((*buffer).as_ref());
-                })
                 .build();
             self.audio_context_impl
                 .decode_audio_data(audio_data, callbacks);

components/script/dom/offlineaudiocontext.rs

@@ -144,6 +144,10 @@ impl OfflineAudioContextMethods for OfflineAudioContext {
                     task!(resolve: move || {
                         let this = this.root();
                         let processed_audio = processed_audio.lock().unwrap();
+                        let processed_audio: Vec<_> = processed_audio
+                            .chunks(this.length as usize)
+                            .map(|channel| channel.to_vec())
+                            .collect();
                         let buffer = AudioBuffer::new(
                             &this.global().as_window(),
                             this.channel_count,