2 files changed, 12 insertions, 6 deletions
diff --git a/testing/web-platform/tests/webrtc-svc/RTCRtpParameters-scalability.html b/testing/web-platform/tests/webrtc-svc/RTCRtpParameters-scalability.html
index ff28c2b5e9..134a28bd5e 100644
--- a/testing/web-platform/tests/webrtc-svc/RTCRtpParameters-scalability.html
+++ b/testing/web-platform/tests/webrtc-svc/RTCRtpParameters-scalability.html
@@ -78,13 +78,17 @@
     const param = transceiver.sender.getParameters();
     const encoding = param.encodings[0];
     assert_true('scalabilityMode' in encoding);
+
     // If L3T3 is not supported at all, abort test.
     assert_implements_optional(encoding.scalabilityMode === 'L3T3');
-    // Pick a codec known to not have L3T3 support
-    const capabilities = RTCRtpSender.getCapabilities('video');
-    const codec = capabilities.codecs.find(c => c.mimeType === 'video/VP8');
-    assert_true(codec !== undefined);
-    transceiver.setCodecPreferences([codec]);
+
+    pc2.ontrack = e => {
+      // Pick a codec known to not have L3T3 support.
+      const capabilities = RTCRtpReceiver.getCapabilities('video');
+      const codec = capabilities.codecs.find(c => c.mimeType === 'video/VP8');
+      assert_true(codec !== undefined);
+      e.transceiver.setCodecPreferences([codec]);
+    }
     exchangeIceCandidates(pc1, pc2);
     await exchangeOfferAnswer(pc1, pc2);
     const sendParams = pc1.getSenders()[0].getParameters();
diff --git a/testing/web-platform/tests/webrtc-svc/svc-helper.js b/testing/web-platform/tests/webrtc-svc/svc-helper.js
index e73ccfa750..6a357f085b 100644
--- a/testing/web-platform/tests/webrtc-svc/svc-helper.js
+++ b/testing/web-platform/tests/webrtc-svc/svc-helper.js
@@ -36,7 +36,9 @@ function createScalabilityTest(mimeType, scalabilityModes) {
       const transceiver = pc1.addTransceiver(track1, {
         sendEncodings: [{ scalabilityMode: scalabilityMode }],
       });
-      transceiver.setCodecPreferences(RTCRtpSender.getCapabilities('video').codecs.filter(c => c.mimeType == mimeType));
+      pc2.addEventListener('track', e => {
+        e.transceiver.setCodecPreferences(RTCRtpReceiver.getCapabilities('video').codecs.filter(c => c.mimeType == mimeType));
+      });
       const haveTrackEvent = new Promise(r => pc2.ontrack = r);
       exchangeIceCandidates(pc1, pc2);
       await exchangeOfferAnswer(pc1, pc2);