1056458-automation-server.patch

From abc8b82e37b4c0150e0471586c3b265b5d6a0434 Mon Sep 17 00:00:00 2001
From: Jordan Santell <jsantell@gmail.com>
Date: Fri, 26 Dec 2014 19:13:05 -0500
Subject: Bug 1056458 - Add backend for recording automation events in
 the web audio API for developer tools. r=vp

diff --git a/browser/devtools/webaudioeditor/test/browser.ini b/browser/devtools/webaudioeditor/test/browser.ini
index fd5e02e..1adf13e 100644
--- a/browser/devtools/webaudioeditor/test/browser.ini
+++ b/browser/devtools/webaudioeditor/test/browser.ini
@@ -5,31 +5,36 @@ support-files =
   doc_complex-context.html
   doc_simple-node-creation.html
   doc_buffer-and-array.html
   doc_media-node-creation.html
   doc_destroy-nodes.html
   doc_connect-param.html
   doc_connect-multi-param.html
   doc_iframe-context.html
+  doc_automation.html
   440hz_sine.ogg
   head.js
 
 [browser_audionode-actor-get-param-flags.js]
 [browser_audionode-actor-get-params-01.js]
 [browser_audionode-actor-get-params-02.js]
 [browser_audionode-actor-get-set-param.js]
 [browser_audionode-actor-get-type.js]
 [browser_audionode-actor-is-source.js]
 [browser_audionode-actor-bypass.js]
 [browser_audionode-actor-connectnode-disconnect.js]
 [browser_audionode-actor-connectparam.js]
+[browser_audionode-actor-add-automation-event.js]
+[browser_audionode-actor-get-automation-data-01.js]
+[browser_audionode-actor-get-automation-data-02.js]
 [browser_webaudio-actor-simple.js]
 [browser_webaudio-actor-destroy-node.js]
 [browser_webaudio-actor-connect-param.js]
+[browser_webaudio-actor-automation-event.js]
 
 [browser_wa_destroy-node-01.js]
 
 [browser_wa_first-run.js]
 [browser_wa_reset-01.js]
 [browser_wa_reset-02.js]
 [browser_wa_reset-03.js]
 [browser_wa_reset-04.js]
diff --git a/browser/devtools/webaudioeditor/test/browser_audionode-actor-add-automation-event.js b/browser/devtools/webaudioeditor/test/browser_audionode-actor-add-automation-event.js
new file mode 100644
index 0000000..0e96b83
--- /dev/null
+++ b/browser/devtools/webaudioeditor/test/browser_audionode-actor-add-automation-event.js
@@ -0,0 +1,52 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * Test AudioNode#addAutomationEvent();
+ */
+
+add_task(function*() {
+  let { target, front } = yield initBackend(SIMPLE_CONTEXT_URL);
+  let [_, [destNode, oscNode, gainNode]] = yield Promise.all([
+    front.setup({ reload: true }),
+    get3(front, "create-node")
+  ]);
+  let count = 0;
+  let counter = () => count++;
+  front.on("automation-event", counter);
+
+  let t0 = 0, t1 = 0.1, t2 = 0.2, t3 = 0.3, t4 = 0.4, t5 = 0.6, t6 = 0.7, t7 = 1;
+  let curve = [-1, 0, 1];
+  yield oscNode.addAutomationEvent("frequency", "setValueAtTime", [0.2, t0]);
+  yield oscNode.addAutomationEvent("frequency", "setValueAtTime", [0.3, t1]);
+  yield oscNode.addAutomationEvent("frequency", "setValueAtTime", [0.4, t2]);
+  yield oscNode.addAutomationEvent("frequency", "linearRampToValueAtTime", [1, t3]);
+  yield oscNode.addAutomationEvent("frequency", "linearRampToValueAtTime", [0.15, t4]);
+  yield oscNode.addAutomationEvent("frequency", "exponentialRampToValueAtTime", [0.75, t5]);
+  yield oscNode.addAutomationEvent("frequency", "exponentialRampToValueAtTime", [0.5, t6]);
+  yield oscNode.addAutomationEvent("frequency", "setValueCurveAtTime", [curve, t7, t7 - t6]);
+  yield oscNode.addAutomationEvent("frequency", "setTargetAtTime", [20, 2, 5]);
+
+  ok(true, "successfully set automation events for valid automation events");
+
+  try {
+    yield oscNode.addAutomationEvent("frequency", "notAMethod", 20, 2, 5);
+    ok(false, "non-automation methods should not be successful");
+  } catch (e) {
+    ok(/invalid/.test(e.message), "AudioNode:addAutomationEvent fails for invalid automation methods");
+  }
+
+  try {
+    yield oscNode.addAutomationEvent("invalidparam", "setValueAtTime", 0.2, t0);
+    ok(false, "automating non-AudioParams should not be successful");
+  } catch (e) {
+    ok(/invalid/.test(e.message), "AudioNode:addAutomationEvent fails for a non AudioParam");
+  }
+
+  front.off("automation-event", counter);
+
+  is(count, 9,
+    "when calling `addAutomationEvent`, the WebAudioActor should still fire `automation-event`.");
+
+  yield removeTab(target.tab);
+});
diff --git a/browser/devtools/webaudioeditor/test/browser_audionode-actor-get-automation-data-01.js b/browser/devtools/webaudioeditor/test/browser_audionode-actor-get-automation-data-01.js
new file mode 100644
index 0000000..8bb35d2
--- /dev/null
+++ b/browser/devtools/webaudioeditor/test/browser_audionode-actor-get-automation-data-01.js
@@ -0,0 +1,53 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * Test AudioNode#addAutomationEvent() checking automation values, also using
+ * a curve as the last event to check duration spread.
+ */
+
+add_task(function*() {
+  let { target, front } = yield initBackend(SIMPLE_CONTEXT_URL);
+  let [_, [destNode, oscNode, gainNode]] = yield Promise.all([
+    front.setup({ reload: true }),
+    get3(front, "create-node")
+  ]);
+
+  let t0 = 0, t1 = 0.1, t2 = 0.2, t3 = 0.3, t4 = 0.4, t5 = 0.6, t6 = 0.7, t7 = 1;
+  let curve = [-1, 0, 1];
+  yield oscNode.addAutomationEvent("frequency", "setValueAtTime", [0.2, t0]);
+  yield oscNode.addAutomationEvent("frequency", "setValueAtTime", [0.3, t1]);
+  yield oscNode.addAutomationEvent("frequency", "setValueAtTime", [0.4, t2]);
+  yield oscNode.addAutomationEvent("frequency", "linearRampToValueAtTime", [1, t3]);
+  yield oscNode.addAutomationEvent("frequency", "linearRampToValueAtTime", [0.15, t4]);
+  yield oscNode.addAutomationEvent("frequency", "exponentialRampToValueAtTime", [0.75, t5]);
+  yield oscNode.addAutomationEvent("frequency", "exponentialRampToValueAtTime", [0.05, t6]);
+  // End with a curve here so we can get proper results on the last event (which takes into account
+  // duration)
+  yield oscNode.addAutomationEvent("frequency", "setValueCurveAtTime", [curve, t6, t7 - t6]);
+
+  let { events, values } = yield oscNode.getAutomationData("frequency");
+
+  is(events.length, 8, "8 recorded events returned.");
+  is(values.length, 2000, "2000 value points returned.");
+
+  checkAutomationValue(values, 0.05, 0.2);
+  checkAutomationValue(values, 0.1, 0.3);
+  checkAutomationValue(values, 0.15, 0.3);
+  checkAutomationValue(values, 0.2, 0.4);
+  checkAutomationValue(values, 0.25, 0.7);
+  checkAutomationValue(values, 0.3, 1);
+  checkAutomationValue(values, 0.35, 0.575);
+  checkAutomationValue(values, 0.4, 0.15);
+  checkAutomationValue(values, 0.45, 0.15 * Math.pow(0.75/0.15,0.05/0.2));
+  checkAutomationValue(values, 0.5, 0.15 * Math.pow(0.75/0.15,0.5));
+  checkAutomationValue(values, 0.55, 0.15 * Math.pow(0.75/0.15,0.15/0.2));
+  checkAutomationValue(values, 0.6, 0.75);
+  checkAutomationValue(values, 0.65, 0.75 * Math.pow(0.05/0.75, 0.5));
+  checkAutomationValue(values, 0.705, -1); // Increase this time a bit to prevent off by the previous exponential amount
+  checkAutomationValue(values, 0.8, 0);
+  checkAutomationValue(values, 0.9, 1);
+  checkAutomationValue(values, 1, 1);
+
+  yield removeTab(target.tab);
+});
diff --git a/browser/devtools/webaudioeditor/test/browser_audionode-actor-get-automation-data-02.js b/browser/devtools/webaudioeditor/test/browser_audionode-actor-get-automation-data-02.js
new file mode 100644
index 0000000..b7bd141
--- /dev/null
+++ b/browser/devtools/webaudioeditor/test/browser_audionode-actor-get-automation-data-02.js
@@ -0,0 +1,38 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * Test AudioNode#addAutomationEvent() when automation series ends with
+ * `setTargetAtTime`, which approaches its target to infinity.
+ */
+
+add_task(function*() {
+  let { target, front } = yield initBackend(SIMPLE_CONTEXT_URL);
+  let [_, [destNode, oscNode, gainNode]] = yield Promise.all([
+    front.setup({ reload: true }),
+    get3(front, "create-node")
+  ]);
+
+  let t0 = 0, t1 = 0.1, t2 = 0.2, t3 = 0.3, t4 = 0.4, t5 = 0.6, t6 = 0.7, t7 = 1;
+  yield oscNode.addAutomationEvent("frequency", "setValueAtTime", [0.2, t0]);
+  yield oscNode.addAutomationEvent("frequency", "setValueAtTime", [0.3, t1]);
+  yield oscNode.addAutomationEvent("frequency", "setValueAtTime", [0.4, t2]);
+  yield oscNode.addAutomationEvent("frequency", "linearRampToValueAtTime", [1, t3]);
+  yield oscNode.addAutomationEvent("frequency", "linearRampToValueAtTime", [0.15, t4]);
+  yield oscNode.addAutomationEvent("frequency", "exponentialRampToValueAtTime", [0.75, t5]);
+  yield oscNode.addAutomationEvent("frequency", "exponentialRampToValueAtTime", [0.05, t6]);
+  // End with a setTargetAtTime event, as the target approaches infinity, which will
+  // give us more points to render than the default 2000
+  yield oscNode.addAutomationEvent("frequency", "setTargetAtTime", [1, t7, 0.5]);
+
+  let { events, values } = yield oscNode.getAutomationData("frequency");
+
+  is(events.length, 8, "8 recorded events returned.");
+  is(values.length, 4000, "6000 value points returned when ending with exponentiall approaching automator.");
+
+  checkAutomationValue(values, 1, 0.05);
+  checkAutomationValue(values, 2, 0.87);
+  checkAutomationValue(values, 3, 0.98);
+
+  yield removeTab(target.tab);
+});
diff --git a/browser/devtools/webaudioeditor/test/browser_webaudio-actor-automation-event.js b/browser/devtools/webaudioeditor/test/browser_webaudio-actor-automation-event.js
new file mode 100644
index 0000000..407754e
--- /dev/null
+++ b/browser/devtools/webaudioeditor/test/browser_webaudio-actor-automation-event.js
@@ -0,0 +1,51 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * Test that the WebAudioActor receives and emits the `automation-event` events
+ * with correct arguments from the content.
+ */
+
+add_task(function*() {
+  let { target, front } = yield initBackend(AUTOMATION_URL);
+  let events = [];
+
+  let expected = [
+    ["setValueAtTime", 0.2, 0],
+    ["linearRampToValueAtTime", 1, 0.3],
+    ["exponentialRampToValueAtTime", 0.75, 0.6],
+    ["setValueCurveAtTime", [-1, 0 ,1], 0.7, 0.3],
+  ];
+
+  front.on("automation-event", onAutomationEvent);
+
+  let [_, __, [destNode, oscNode, gainNode], [connect1, connect2]] = yield Promise.all([
+    front.setup({ reload: true }),
+    once(front, "start-context"),
+    get3(front, "create-node"),
+    get2(front, "connect-node")
+  ]);
+
+  is(events.length, 4, "correct number of events fired");
+
+  function onAutomationEvent (e) {
+    let { eventName, paramName, args } = e;
+    let exp = expected[events.length];
+
+    is(eventName, exp[0], "correct eventName in event");
+    is(paramName, "frequency", "correct paramName in event");
+    is(args.length, exp.length - 1, "correct length in args");
+    args.forEach((a, i) => {
+      // In the case of an array
+      if (typeof a === "object") {
+        a.forEach((f, j) => is(f, exp[i + 1][j], "correct argument in args"));
+      } else {
+        is(a, exp[i + 1], "correct argument in args");
+      }
+    });
+    events.push([eventName].concat(args));
+  }
+
+  front.off("automation-event", onAutomationEvent);
+  yield removeTab(target.tab);
+});
diff --git a/browser/devtools/webaudioeditor/test/doc_automation.html b/browser/devtools/webaudioeditor/test/doc_automation.html
new file mode 100644
index 0000000..6f07420
--- /dev/null
+++ b/browser/devtools/webaudioeditor/test/doc_automation.html
@@ -0,0 +1,30 @@
+<!-- Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/ -->
+<!doctype html>
+
+<html>
+  <head>
+    <meta charset="utf-8"/>
+    <title>Web Audio Editor test page</title>
+  </head>
+
+  <body>
+
+    <script type="text/javascript;version=1.8">
+      "use strict";
+
+      let ctx = new AudioContext();
+      let osc = ctx.createOscillator();
+      let gain = ctx.createGain();
+      gain.gain.value = 0;
+      osc.frequency.setValueAtTime(0.2, 0);
+      osc.frequency.linearRampToValueAtTime(1, 0.3);
+      osc.frequency.exponentialRampToValueAtTime(0.75, 0.6);
+      osc.frequency.setValueCurveAtTime(new Float32Array([-1, 0, 1]), 0.7, 0.3);
+      osc.connect(gain);
+      gain.connect(ctx.destination);
+      osc.start(0);
+    </script>
+  </body>
+
+</html>
diff --git a/browser/devtools/webaudioeditor/test/head.js b/browser/devtools/webaudioeditor/test/head.js
index 7306798..d9a0d2f 100644
--- a/browser/devtools/webaudioeditor/test/head.js
+++ b/browser/devtools/webaudioeditor/test/head.js
@@ -4,17 +4,17 @@
 
 const { classes: Cc, interfaces: Ci, utils: Cu, results: Cr } = Components;
 
 let { Services } = Cu.import("resource://gre/modules/Services.jsm", {});
 
 // Enable logging for all the tests. Both the debugger server and frontend will
 // be affected by this pref.
 let gEnableLogging = Services.prefs.getBoolPref("devtools.debugger.log");
-Services.prefs.setBoolPref("devtools.debugger.log", true);
+Services.prefs.setBoolPref("devtools.debugger.log", false);
 
 let { Task } = Cu.import("resource://gre/modules/Task.jsm", {});
 let { Promise } = Cu.import("resource://gre/modules/Promise.jsm", {});
 let { gDevTools } = Cu.import("resource:///modules/devtools/gDevTools.jsm", {});
 let { devtools } = Cu.import("resource://gre/modules/devtools/Loader.jsm", {});
 let { DebuggerServer } = Cu.import("resource://gre/modules/devtools/dbg-server.jsm", {});
 
 let { WebAudioFront } = devtools.require("devtools/server/actors/webaudio");
@@ -25,16 +25,17 @@ const SIMPLE_CONTEXT_URL = EXAMPLE_URL + "doc_simple-context.html";
 const COMPLEX_CONTEXT_URL = EXAMPLE_URL + "doc_complex-context.html";
 const SIMPLE_NODES_URL = EXAMPLE_URL + "doc_simple-node-creation.html";
 const MEDIA_NODES_URL = EXAMPLE_URL + "doc_media-node-creation.html";
 const BUFFER_AND_ARRAY_URL = EXAMPLE_URL + "doc_buffer-and-array.html";
 const DESTROY_NODES_URL = EXAMPLE_URL + "doc_destroy-nodes.html";
 const CONNECT_PARAM_URL = EXAMPLE_URL + "doc_connect-param.html";
 const CONNECT_MULTI_PARAM_URL = EXAMPLE_URL + "doc_connect-multi-param.html";
 const IFRAME_CONTEXT_URL = EXAMPLE_URL + "doc_iframe-context.html";
+const AUTOMATION_URL = EXAMPLE_URL + "doc_automation.html";
 
 // All tests are asynchronous.
 waitForExplicitFinish();
 
 let gToolEnabled = Services.prefs.getBoolPref("devtools.webaudioeditor.enabled");
 
 gDevTools.testing = true;
 
@@ -389,16 +390,46 @@ function countGraphObjects (win) {
 */
 function forceCC () {
   SpecialPowers.DOMWindowUtils.cycleCollect();
   SpecialPowers.DOMWindowUtils.garbageCollect();
   SpecialPowers.DOMWindowUtils.garbageCollect();
 }
 
 /**
+ * Takes a `values` array of automation value entries,
+ * looking for the value at `time` seconds, checking
+ * to see if the value is close to `expected`.
+ */
+function checkAutomationValue (values, time, expected) {
+  // Remain flexible on values as we can approximate points
+  let EPSILON = 0.01;
+
+  let value = getValueAt(values, time);
+  ok(Math.abs(value - expected) < EPSILON, "Timeline value at " + time + " with value " + value + " should have value very close to " + expected);
+
+  /**
+   * Entries are ordered in `values` according to time, so if we can't find an exact point
+   * on a time of interest, return the point in between the threshold. This should
+   * get us a very close value.
+   */
+  function getValueAt (values, time) {
+    for (let i = 0; i < values.length; i++) {
+      if (values[i].t === time) {
+        return values[i].value;
+      }
+      if (values[i].t > time) {
+        return (values[i - 1].value + values[i].value) / 2;
+      }
+    }
+    return values[values.length - 1].value;
+  }
+}
+
+/**
  * List of audio node properties to test against expectations of the AudioNode actor
  */
 
 const NODE_DEFAULT_VALUES = {
   "AudioDestinationNode": {},
   "MediaElementAudioSourceNode": {},
   "MediaStreamAudioSourceNode": {},
   "MediaStreamAudioDestinationNode": {
diff --git a/toolkit/devtools/server/actors/webaudio.js b/toolkit/devtools/server/actors/webaudio.js
index 09aebd6..2988999 100644
--- a/toolkit/devtools/server/actors/webaudio.js
+++ b/toolkit/devtools/server/actors/webaudio.js
@@ -8,32 +8,41 @@ const {Cc, Ci, Cu, Cr} = require("chrome");
 const Services = require("Services");
 
 const { Promise: promise } = Cu.import("resource://gre/modules/Promise.jsm", {});
 const events = require("sdk/event/core");
 const { on: systemOn, off: systemOff } = require("sdk/system/events");
 const protocol = require("devtools/server/protocol");
 const { CallWatcherActor, CallWatcherFront } = require("devtools/server/actors/call-watcher");
 const { ThreadActor } = require("devtools/server/actors/script");
+const AutomationTimeline = require("./utils/automation-timeline");
 
 const { on, once, off, emit } = events;
 const { types, method, Arg, Option, RetVal } = protocol;
 
+const AUTOMATION_GRANULARITY = 2000;
+const AUTOMATION_GRANULARITY_MAX = 6000;
+
 const AUDIO_GLOBALS = [
-  "AudioContext", "AudioNode"
+  "AudioContext", "AudioNode", "AudioParam"
 ];
 
 const NODE_CREATION_METHODS = [
   "createBufferSource", "createMediaElementSource", "createMediaStreamSource",
   "createMediaStreamDestination", "createScriptProcessor", "createAnalyser",
   "createGain", "createDelay", "createBiquadFilter", "createWaveShaper",
   "createPanner", "createConvolver", "createChannelSplitter", "createChannelMerger",
   "createDynamicsCompressor", "createOscillator"
 ];
 
+const AUTOMATION_METHODS = [
+  "setValueAtTime", "linearRampToValueAtTime", "exponentialRampToValueAtTime",
+  "setTargetAtTime", "setValueCurveAtTime"
+];
+
 const NODE_ROUTING_METHODS = [
   "connect", "disconnect"
 ];
 
 const NODE_PROPERTIES = {
   "OscillatorNode": {
     "type": {},
     "frequency": {},
@@ -125,21 +134,31 @@ let AudioNodeActor = exports.AudioNodeActor = protocol.ActorClass({
     protocol.Actor.prototype.initialize.call(this, conn);
 
     // Store ChromeOnly property `id` to identify AudioNode,
     // rather than storing a strong reference, and store a weak
     // ref to underlying node for controlling.
     this.nativeID = node.id;
     this.node = Cu.getWeakReference(node);
 
+    // Stores the AutomationTimelines for this node's AudioParams.
+    this.automation = {};
+
     try {
       this.type = getConstructorName(node);
     } catch (e) {
       this.type = "";
     }
+
+    // Create automation timelines for all AudioParams
+    Object.keys(NODE_PROPERTIES[this.type])
+      .filter(isAudioParam.bind(null, node))
+      .forEach(paramName => {
+        this.automation[paramName] = new AutomationTimeline(node[paramName].defaultValue);
+      });
   },
 
   /**
    * Returns the name of the audio type.
    * Examples: "OscillatorNode", "MediaElementAudioSourceNode"
    */
   getType: method(function () {
     return this.type;
@@ -207,20 +226,23 @@ let AudioNodeActor = exports.AudioNodeActor = protocol.ActorClass({
   setParam: method(function (param, value) {
     let node = this.node.get();
 
     if (node === null) {
       return CollectedAudioNodeError();
     }
 
     try {
-      if (isAudioParam(node, param))
+      if (isAudioParam(node, param)) {
         node[param].value = value;
-      else
+        this.automation[param].setValue(value);
+      }
+      else {
         node[param] = value;
+      }
       return undefined;
     } catch (e) {
       return constructError(e);
     }
   }, {
     request: {
       param: Arg(0, "string"),
       value: Arg(1, "nullable:primitive")
@@ -279,17 +301,17 @@ let AudioNodeActor = exports.AudioNodeActor = protocol.ActorClass({
     request: { param: Arg(0, "string") },
     response: { flags: RetVal("nullable:primitive") }
   }),
 
   /**
    * Get an array of objects each containing a `param` and `value` property,
    * corresponding to a property name and current value of the audio node.
    */
-  getParams: method(function (param) {
+  getParams: method(function () {
     let props = Object.keys(NODE_PROPERTIES[this.type]);
     return props.map(prop =>
       ({ param: prop, value: this.getParam(prop), flags: this.getParamFlags(prop) }));
   }, {
     response: { params: RetVal("json") }
   }),
 
   /**
@@ -367,18 +389,143 @@ let AudioNodeActor = exports.AudioNodeActor = protocol.ActorClass({
       // patched method that fires the webaudio actor's `disconnect` event.
       XPCNativeWrapper.unwrap(node).disconnect(output);
     } catch (e) {
       return constructError(e);
     }
   }, {
     request: { output: Arg(0, "nullable:number") },
     response: { error: RetVal("nullable:json") }
-  })
+  }),
+
+  getAutomationData: method(function (paramName) {
+    let timeline = this.automation[paramName];
+    let events = timeline.events;
+    let values = [];
+    let i = 0;
+
+    if (!timeline) {
+      return null;
+    }
+
+    if (!timeline.events.length) {
+      return { events, values };
+    }
+
+    let firstEvent = events[0];
+    let lastEvent = events[timeline.events.length - 1];
+    // `setValueCurveAtTime` will have a duration value -- other
+    // events will have duration of `0`.
+    let timeDelta = (lastEvent.time + lastEvent.duration) - firstEvent.time;
+    let scale = timeDelta / AUTOMATION_GRANULARITY;
+
+    for (; i < AUTOMATION_GRANULARITY; i++) {
+      let t = firstEvent.time + (i * scale);
+      let value = timeline.getValueAtTime(t);
+      values.push({ t, value });
+    }
+
+    // If the last event is setTargetAtTime, the automation
+    // doesn't actually begin until the event's time, and exponentially
+    // approaches the target value. In this case, we add more values
+    // until we're "close enough" to the target.
+    if (lastEvent.type === "setTargetAtTime") {
+      for (; i < AUTOMATION_GRANULARITY_MAX; i++) {
+        let t = firstEvent.time + (++i * scale);
+        let value = timeline.getValueAtTime(t);
+        values.push({ t, value });
+      }
+    }
+
+    return { events, values };
+  }, {
+    request: { paramName: Arg(0, "string") },
+    response: { values: RetVal("nullable:json") }
+  }),
+
+  /**
+   * Called via WebAudioActor, registers an automation event
+   * for the AudioParam called.
+   *
+   * @param String paramName
+   *        Name of the AudioParam.
+   * @param String eventName
+   *        Name of the automation event called.
+   * @param Array args
+   *        Arguments passed into the automation call.
+   */
+  addAutomationEvent: method(function (paramName, eventName, args=[]) {
+    let node = this.node.get();
+    let timeline = this.automation[paramName];
+
+    if (node === null) {
+      return CollectedAudioNodeError();
+    }
+
+    if (!timeline || !node[paramName][eventName]) {
+      return InvalidCommandError();
+    }
+
+    try {
+      // Using the unwrapped node and parameter, the corresponding
+      // WebAudioActor event will be fired, subsequently calling
+      // `_recordAutomationEvent`. Some finesse is required to handle
+      // the cast of TypedArray arguments over the protocol, which is
+      // taken care of below. The event will cast the argument back
+      // into an array to be broadcasted from WebAudioActor, but the
+      // double-casting will only occur when starting from `addAutomationEvent`,
+      // which is only used in tests.
+      let param = XPCNativeWrapper.unwrap(node[paramName]);
+
+      // If calling `setValueCurveAtTime`, the first argument
+      // is a Float32Array, which won't be able to be serialized
+      // over the protocol. Cast a normal array to a Float32Array here.
+      if (eventName === "setValueCurveAtTime") {
+        let contentGlobal = Cu.getGlobalForObject(param);
+        // Since we cannot iterate over and modify the actual Float32Array
+        // in the content, we'll have to pass in an array to the constructor
+        // from the same context, since we can iterate over non-TypedArrays.
+        let contentArray = copyInto(new contentGlobal.Array(), args[0]);
+
+        // Create a Float32Array from the content, seeding with an array
+        // from the same scope.
+        let curve = new contentGlobal.Float32Array(contentArray);
+        args[0] = curve;
+      }
+
+      param[eventName].apply(param, args);
+    } catch (e) {
+      return constructError(e);
+    }
+  }, {
+    request: {
+      paramName: Arg(0, "string"),
+      eventName: Arg(1, "string"),
+      args: Arg(2, "nullable:json")
+    },
+    response: { error: RetVal("nullable:json") }
+  }),
 
+  /**
+   * Registers the automation event in the AudioNodeActor's
+   * internal timeline. Called when setting automation via
+   * `addAutomationEvent`, or from the WebAudioActor's listening
+   * to the event firing via content.
+   *
+   * @param String paramName
+   *        Name of the AudioParam.
+   * @param String eventName
+   *        Name of the automation event called.
+   * @param Array args
+   *        Arguments passed into the automation call.
+   */
+  _recordAutomationEvent: function (paramName, eventName, args) {
+    let timeline = this.automation[paramName];
+    timeline[eventName].apply(timeline, args);
+  }
 });
 
 /**
  * The corresponding Front object for the AudioNodeActor.
  */
 let AudioNodeFront = protocol.FrontClass(AudioNodeActor, {
   initialize: function (client, form) {
     protocol.Front.prototype.initialize.call(this, client, form);
@@ -470,20 +617,23 @@ let WebAudioActor = exports.WebAudioActor = protocol.ActorClass({
     // All Web Audio nodes inherit from AudioNode's prototype, so
     // hook into the `connect` and `disconnect` methods
     if (WebAudioFront.NODE_ROUTING_METHODS.has(name)) {
       this._handleRoutingCall(functionCall);
     }
     else if (WebAudioFront.NODE_CREATION_METHODS.has(name)) {
       this._handleCreationCall(functionCall);
     }
+    else if (WebAudioFront.AUTOMATION_METHODS.has(name)) {
+      this._handleAutomationCall(functionCall);
+    }
   },
 
   _handleRoutingCall: function(functionCall) {
-    let { caller, args, window, name } = functionCall.details;
+    let { caller, args, name } = functionCall.details;
     let source = caller;
     let dest = args[0];
     let isAudioParam = dest ? getConstructorName(dest) === "AudioParam" : false;
 
     // audionode.connect(param)
     if (name === "connect" && isAudioParam) {
       this._onConnectParam(source, dest);
     }
@@ -508,16 +658,36 @@ let WebAudioActor = exports.WebAudioActor = protocol.ActorClass({
       // and trigger a `create-node` event for the context destination
       this._onStartContext();
       this._onCreateNode(caller.destination);
       this._firstNodeCreated = true;
     }
     this._onCreateNode(result);
   },
 
+  _handleAutomationCall: function (functionCall) {
+    let { caller, name, args } = functionCall.details;
+    let wrappedParam = new XPCNativeWrapper(caller);
+
+    // Sanitize arguments, as these should all be numbers,
+    // with the exception of a TypedArray, which needs
+    // casted to an Array
+    args = sanitizeAutomationArgs(args);
+
+    let nodeActor = this._getActorByNativeID(wrappedParam._parentID);
+    nodeActor._recordAutomationEvent(wrappedParam._paramName, name, args);
+
+    this._onAutomationEvent({
+      node: nodeActor,
+      paramName: wrappedParam._paramName,
+      eventName: name,
+      args: args
+    });
+  },
+
   /**
    * Stops listening for document global changes and puts this actor
    * to hibernation. This method is called automatically just before the
    * actor is destroyed.
    */
   finalize: method(function() {
     if (!this._initialized) {
       return;
@@ -566,16 +736,23 @@ let WebAudioActor = exports.WebAudioActor = protocol.ActorClass({
     },
     "create-node": {
       type: "createNode",
       source: Arg(0, "audionode")
     },
     "destroy-node": {
       type: "destroyNode",
       source: Arg(0, "audionode")
+    },
+    "automation-event": {
+      type: "automationEvent",
+      node: Option(0, "audionode"),
+      paramName: Option(0, "string"),
+      eventName: Option(0, "string"),
+      args: Option(0, "json")
     }
   },
 
   /**
    * Helper for constructing an AudioNodeActor, assigning to
    * internal weak map, and tracking via `manage` so it is assigned
    * an `actorID`.
    */
@@ -707,16 +884,28 @@ let WebAudioActor = exports.WebAudioActor = protocol.ActorClass({
    * Ensures that the new global has recording on
    * so we can proxy the function calls.
    */
   _onGlobalCreated: function () {
     this._callWatcher.resumeRecording();
   },
 
   /**
+   * Fired when an automation event is added to an AudioNode.
+   */
+  _onAutomationEvent: function ({node, paramName, eventName, args}) {
+    emit(this, "automation-event",  {
+      node: node,
+      paramName: paramName,
+      eventName: eventName,
+      args: args
+    });
+  },
+
+  /**
    * Called when the underlying ContentObserver fires `global-destroyed`
    * so we can cleanup some things between the global being destroyed and
    * when the actor's `finalize` method gets called.
    */
   _onGlobalDestroyed: function ({id}) {
     if (this._callWatcher._tracedWindowId !== id) {
       return;
     }
@@ -733,16 +922,17 @@ let WebAudioActor = exports.WebAudioActor = protocol.ActorClass({
  */
 let WebAudioFront = exports.WebAudioFront = protocol.FrontClass(WebAudioActor, {
   initialize: function(client, { webaudioActor }) {
     protocol.Front.prototype.initialize.call(this, client, { actor: webaudioActor });
     this.manage(this);
   }
 });
 
+WebAudioFront.AUTOMATION_METHODS = new Set(AUTOMATION_METHODS);
 WebAudioFront.NODE_CREATION_METHODS = new Set(NODE_CREATION_METHODS);
 WebAudioFront.NODE_ROUTING_METHODS = new Set(NODE_ROUTING_METHODS);
 
 /**
  * Determines whether or not property is an AudioParam.
  *
  * @param AudioNode node
  *        An AudioNode.
@@ -776,16 +966,23 @@ function constructError (err) {
  */
 function CollectedAudioNodeError () {
   return {
     message: "AudioNode has been garbage collected and can no longer be reached.",
     type: "UnreachableAudioNode"
   };
 }
 
+function InvalidCommandError () {
+  return {
+    message: "The command on AudioNode is invalid.",
+    type: "InvalidCommand"
+  };
+}
+
 /**
  * Takes an object and converts it's `toString()` form, like
  * "[object OscillatorNode]" or "[object Float32Array]",
  * or XrayWrapper objects like "[object XrayWrapper [object Array]]"
  * to a string of just the constructor name, like "OscillatorNode",
  * or "Float32Array".
  */
 function getConstructorName (obj) {
@@ -802,8 +999,42 @@ function createObjectGrip (value) {
     type: "object",
     preview: {
       kind: "ObjectWithText",
       text: ""
     },
     class: getConstructorName(value)
   };
 }
+
+/**
+ * Converts all TypedArrays of the array that cannot
+ * be passed over the wire into a normal Array equivilent.
+ */
+function sanitizeAutomationArgs (args) {
+  return args.reduce((newArgs, el) => {
+    newArgs.push(typeof el === "object" && getConstructorName(el) === "Float32Array" ? castToArray(el) : el);
+    return newArgs;
+  }, []);
+}
+
+/**
+ * Casts TypedArray to a normal array via a
+ * new scope.
+ */
+function castToArray (typedArray) {
+  // The Xray machinery for TypedArrays denies indexed access on the grounds
+  // that it's slow, and advises callers to do a structured clone instead.
+  let global = Cu.getGlobalForObject(this);
+  let safeView = Cu.cloneInto(typedArray.subarray(), global);
+  return copyInto([], safeView);
+}
+
+/**
+ * Copies values of an array-like `source` into
+ * a similarly array-like `dest`.
+ */
+function copyInto (dest, source) {
+  for (let i = 0; i < source.length; i++) {
+    dest[i] = source[i];
+  }
+  return dest;
+}
-- 
2.2.1