--- a/dom/media/webm/WebMDemuxer.cpp
+++ b/dom/media/webm/WebMDemuxer.cpp
@@ -3,16 +3,19 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "nsError.h"
 #include "MediaDecoderStateMachine.h"
 #include "AbstractMediaDecoder.h"
 #include "MediaResource.h"
+#ifdef MOZ_AV1
+#include "AOMDecoder.h"
+#endif
 #include "OpusDecoder.h"
 #include "VPXDecoder.h"
 #include "WebMDemuxer.h"
 #include "WebMBufferedParser.h"
 #include "gfx2DGlue.h"
 #include "mozilla/Atomics.h"
 #include "mozilla/EndianUtils.h"
 #include "mozilla/SharedThreadPool.h"
@@ -322,16 +325,19 @@ WebMDemuxer::ReadMetadata()
       mVideoCodec = nestegg_track_codec_id(context, track);
       switch(mVideoCodec) {
         case NESTEGG_CODEC_VP8:
           mInfo.mVideo.mMimeType = "video/webm; codecs=vp8";
           break;
         case NESTEGG_CODEC_VP9:
           mInfo.mVideo.mMimeType = "video/webm; codecs=vp9";
           break;
+        case NESTEGG_CODEC_AV1:
+          mInfo.mVideo.mMimeType = "video/webm; codecs=av1";
+          break;
         default:
           NS_WARNING("Unknown WebM video codec");
           return NS_ERROR_FAILURE;
       }
       // Picture region, taking into account cropping, before scaling
       // to the display size.
       unsigned int cropH = params.crop_right + params.crop_left;
       unsigned int cropV = params.crop_bottom + params.crop_top;
@@ -677,27 +683,42 @@ WebMDemuxer::GetNextPacket(TrackInfo::Tr
         auto sample = MakeSpan(data, length);
         switch (mVideoCodec) {
         case NESTEGG_CODEC_VP8:
           isKeyframe = VPXDecoder::IsKeyframe(sample, VPXDecoder::Codec::VP8);
           break;
         case NESTEGG_CODEC_VP9:
           isKeyframe = VPXDecoder::IsKeyframe(sample, VPXDecoder::Codec::VP9);
           break;
+#ifdef MOZ_AV1
+        case NESTEGG_CODEC_AV1:
+          isKeyframe = AOMDecoder::IsKeyframe(sample);
+          break;
+#endif
         default:
           NS_WARNING("Cannot detect keyframes in unknown WebM video codec");
           return NS_ERROR_FAILURE;
         }
         if (isKeyframe) {
           // For both VP8 and VP9, we only look for resolution changes
           // on keyframes. Other resolution changes are invalid.
-          auto codec = mVideoCodec == NESTEGG_CODEC_VP8
-                       ? VPXDecoder::Codec::VP8
-                       : VPXDecoder::Codec::VP9;
-          auto dimensions = VPXDecoder::GetFrameSize(sample, codec);
+          auto dimensions = nsIntSize(0, 0);
+          switch (mVideoCodec) {
+          case NESTEGG_CODEC_VP8:
+            dimensions = VPXDecoder::GetFrameSize(sample, VPXDecoder::Codec::VP8);
+            break;
+          case NESTEGG_CODEC_VP9:
+            dimensions = VPXDecoder::GetFrameSize(sample, VPXDecoder::Codec::VP9);
+            break;
+#ifdef MOZ_AV1
+          case NESTEGG_CODEC_AV1:
+            dimensions = AOMDecoder::GetFrameSize(sample);
+            break;
+#endif
+          }
           if (mLastSeenFrameSize.isSome()
               && (dimensions != mLastSeenFrameSize.value())) {
             mInfo.mVideo.mDisplay = dimensions;
             mSharedVideoTrackInfo =
               new TrackInfoSharedPtr(mInfo.mVideo, ++sStreamSourceID);
           }
           mLastSeenFrameSize = Some(dimensions);
         }