diff --git a/index.src.html b/index.src.html
index da0fcc9c..94f6fffe 100644
--- a/index.src.html
+++ b/index.src.html
@@ -262,6 +262,7 @@
   readonly attribute CodecState state;
   readonly attribute unsigned long decodeQueueSize;
   attribute EventHandler ondequeue;
+  attribute EventHandler onDecoderChange;
 
   undefined configure(AudioDecoderConfig config);
   undefined decode(EncodedAudioChunk chunk);
@@ -353,7 +354,10 @@
 : <dfn event for=AudioDecoder>dequeue</dfn>
 :: Fired at the {{AudioDecoder}} when the {{AudioDecoder/decodeQueueSize}} has
     decreased.
-
+    
+: <dfn event for=AudioDecoder>onDecoderChange</dfn>
+:: Fired at the {{AudioDecoder}} when the {{AudioDecoder/powerEfficient}} or
+    {{AudioDecoder/decoderId}} value changes.
 
 Methods {#audiodecoder-methods}
 -------------------------------
@@ -589,6 +593,7 @@
   readonly attribute CodecState state;
   readonly attribute unsigned long decodeQueueSize;
   attribute EventHandler ondequeue;
+  attribute EventHandler onDecoderChange;
 
   undefined configure(VideoDecoderConfig config);
   undefined decode(EncodedVideoChunk chunk);
@@ -684,6 +689,10 @@
 : <dfn event for=VideoDecoder>dequeue</dfn>
 :: Fired at the {{VideoDecoder}} when the {{VideoDecoder/decodeQueueSize}} has
     decreased.
+    
+: <dfn event for=VideoDecoder>onDecoderChange</dfn>
+:: Fired at the {{VideoDecoder}} when the {{VideoDecoder/powerEfficient}} or
+    {{VideoDecoder/decoderId}} value changes.
 
 Methods {#videodecoder-methods}
 -------------------------------
@@ -943,6 +952,7 @@
   readonly attribute CodecState state;
   readonly attribute unsigned long encodeQueueSize;
   attribute EventHandler ondequeue;
+  attribute EventHandler onEncoderChange;
 
   undefined configure(AudioEncoderConfig config);
   undefined encode(AudioData data);
@@ -1038,6 +1048,10 @@
 : <dfn event for=AudioEncoder>dequeue</dfn>
 :: Fired at the {{AudioEncoder}} when the {{AudioEncoder/encodeQueueSize}} has
     decreased.
+    
+: <dfn event for=AudioEncoder>onEncoderChange</dfn>
+:: Fired at the {{AudioEncoder}} when the {{AudioEncoder/powerEfficient}} or
+    {{AudioEncoder/decoderId}} value changes.
 
 Methods {#audioencoder-methods}
 -------------------------------
@@ -1316,6 +1330,7 @@
   readonly attribute CodecState state;
   readonly attribute unsigned long encodeQueueSize;
   attribute EventHandler ondequeue;
+  attribute EventHandler onEncoderChange;
 
   undefined configure(VideoEncoderConfig config);
   undefined encode(VideoFrame frame, optional VideoEncoderEncodeOptions options = {});
@@ -1411,6 +1426,10 @@
 : <dfn event for=VideoEncoder>dequeue</dfn>
 :: Fired at the {{VideoEncoder}} when the {{VideoEncoder/encodeQueueSize}} has
     decreased.
+    
+: <dfn event for=VideoEncoder>onEncoderChange</dfn>
+:: Fired at the {{VideoEncoder}} when the {{VideoEncoder/powerEfficient}} or
+    {{VideoEncoder/decoderId}} value changes.
 
 Methods {#videoencoder-methods}
 -------------------------------