diff --git a/audio/channel_receive_frame_transformer_delegate_unittest.cc b/audio/channel_receive_frame_transformer_delegate_unittest.cc
index b08dcff78d..38ceb6d96d 100644
--- a/audio/channel_receive_frame_transformer_delegate_unittest.cc
+++ b/audio/channel_receive_frame_transformer_delegate_unittest.cc
@@ -146,7 +146,7 @@ TEST(ChannelReceiveFrameTransformerDelegateTest,
 
   delegate->Reset();
   EXPECT_CALL(mock_channel, ReceiveFrame).Times(0);
-  delegate->OnTransformedFrame(std::make_unique<MockTransformableFrame>());
+  delegate->OnTransformedFrame(std::make_unique<MockTransformableAudioFrame>());
   rtc::ThreadManager::ProcessAllMessageQueuesForTesting();
 }
 
diff --git a/audio/channel_send_frame_transformer_delegate.cc b/audio/channel_send_frame_transformer_delegate.cc
index a63f5706ba..e07e1a70c8 100644
--- a/audio/channel_send_frame_transformer_delegate.cc
+++ b/audio/channel_send_frame_transformer_delegate.cc
@@ -160,19 +160,25 @@ void ChannelSendFrameTransformerDelegate::SendFrame(
     std::unique_ptr<TransformableFrameInterface> frame) const {
   MutexLock lock(&send_lock_);
   RTC_DCHECK_RUN_ON(encoder_queue_);
-  RTC_CHECK_EQ(frame->GetDirection(),
-               TransformableFrameInterface::Direction::kSender);
   if (!send_frame_callback_)
     return;
+  uint32_t rtp_start_timestamp = 0;
+  if (frame->GetDirection() ==
+      TransformableFrameInterface::Direction::kSender) {
+    auto* outgoing_frame =
+        static_cast<TransformableOutgoingAudioFrame*>(frame.get());
+    rtp_start_timestamp = outgoing_frame->GetStartTimestamp();
+  }
   auto* transformed_frame =
-      static_cast<TransformableOutgoingAudioFrame*>(frame.get());
+      static_cast<TransformableAudioFrameInterface*>(frame.get());
   send_frame_callback_(
       InterfaceFrameTypeToInternalFrameType(transformed_frame->Type()),
       transformed_frame->GetPayloadType(),
-      transformed_frame->GetTimestamp() -
-          transformed_frame->GetStartTimestamp(),
+      transformed_frame->GetTimestamp() - rtp_start_timestamp,
       transformed_frame->GetData(),
-      *transformed_frame->AbsoluteCaptureTimestamp());
+      transformed_frame->AbsoluteCaptureTimestamp()
+          ? *transformed_frame->AbsoluteCaptureTimestamp()
+          : 0);
 }
 
 std::unique_ptr<TransformableAudioFrameInterface> CloneSenderAudioFrame(
diff --git a/audio/channel_send_frame_transformer_delegate_unittest.cc b/audio/channel_send_frame_transformer_delegate_unittest.cc
index 9196bcb41f..998a6e689a 100644
--- a/audio/channel_send_frame_transformer_delegate_unittest.cc
+++ b/audio/channel_send_frame_transformer_delegate_unittest.cc
@@ -22,7 +22,10 @@
 namespace webrtc {
 namespace {
 
+using ::testing::_;
+using ::testing::ElementsAre;
 using ::testing::NiceMock;
+using ::testing::Return;
 using ::testing::SaveArg;
 
 class MockChannelSend {
@@ -48,6 +51,18 @@ class MockChannelSend {
   }
 };
 
+std::unique_ptr<MockTransformableAudioFrame> CreateMockReceiverFrame() {
+  const uint8_t mock_data[] = {1, 2, 3, 4};
+  std::unique_ptr<MockTransformableAudioFrame> mock_frame =
+      std::make_unique<MockTransformableAudioFrame>();
+  rtc::ArrayView<const uint8_t> payload(mock_data);
+  ON_CALL(*mock_frame, GetData).WillByDefault(Return(payload));
+  ON_CALL(*mock_frame, GetPayloadType).WillByDefault(Return(0));
+  ON_CALL(*mock_frame, GetDirection)
+      .WillByDefault(Return(TransformableFrameInterface::Direction::kReceiver));
+  return mock_frame;
+}
+
 // Test that the delegate registers itself with the frame transformer on Init().
 TEST(ChannelSendFrameTransformerDelegateTest,
      RegisterTransformedFrameCallbackOnInit) {
@@ -104,6 +119,36 @@ TEST(ChannelSendFrameTransformerDelegateTest,
   channel_queue.WaitForPreviouslyPostedTasks();
 }
 
+// Test that when the delegate receives a Incoming frame from the frame
+// transformer, it passes it to the channel using the SendFrameCallback.
+TEST(ChannelSendFrameTransformerDelegateTest,
+     TransformRunsChannelSendCallbackForIncomingFrame) {
+  TaskQueueForTest channel_queue("channel_queue");
+  rtc::scoped_refptr<MockFrameTransformer> mock_frame_transformer =
+      rtc::make_ref_counted<NiceMock<MockFrameTransformer>>();
+  MockChannelSend mock_channel;
+  rtc::scoped_refptr<ChannelSendFrameTransformerDelegate> delegate =
+      rtc::make_ref_counted<ChannelSendFrameTransformerDelegate>(
+          mock_channel.callback(), mock_frame_transformer, &channel_queue);
+  rtc::scoped_refptr<TransformedFrameCallback> callback;
+  EXPECT_CALL(*mock_frame_transformer, RegisterTransformedFrameCallback)
+      .WillOnce(SaveArg<0>(&callback));
+  delegate->Init();
+  ASSERT_TRUE(callback);
+
+  const uint8_t data[] = {1, 2, 3, 4};
+  EXPECT_CALL(mock_channel, SendFrame).Times(0);
+  EXPECT_CALL(mock_channel, SendFrame(_, 0, 0, ElementsAre(1, 2, 3, 4), _));
+  ON_CALL(*mock_frame_transformer, Transform)
+      .WillByDefault(
+          [&callback](std::unique_ptr<TransformableFrameInterface> frame) {
+            callback->OnTransformedFrame(CreateMockReceiverFrame());
+          });
+  delegate->Transform(AudioFrameType::kEmptyFrame, 0, 0, 0, data, sizeof(data),
+                      0, 0);
+  channel_queue.WaitForPreviouslyPostedTasks();
+}
+
 // Test that if the delegate receives a transformed frame after it has been
 // reset, it does not run the SendFrameCallback, as the channel is destroyed
 // after resetting the delegate.
@@ -119,7 +164,7 @@ TEST(ChannelSendFrameTransformerDelegateTest,
 
   delegate->Reset();
   EXPECT_CALL(mock_channel, SendFrame).Times(0);
-  delegate->OnTransformedFrame(std::make_unique<MockTransformableFrame>());
+  delegate->OnTransformedFrame(std::make_unique<MockTransformableAudioFrame>());
   channel_queue.WaitForPreviouslyPostedTasks();
 }
 
diff --git a/test/mock_transformable_frame.h b/test/mock_transformable_frame.h
index 9361aaeb06..35b8d92d22 100644
--- a/test/mock_transformable_frame.h
+++ b/test/mock_transformable_frame.h
@@ -16,14 +16,19 @@
 
 namespace webrtc {
 
-class MockTransformableFrame : public TransformableFrameInterface {
+class MockTransformableAudioFrame : public TransformableAudioFrameInterface {
  public:
   MOCK_METHOD(rtc::ArrayView<const uint8_t>, GetData, (), (const, override));
+  MOCK_METHOD(rtc::ArrayView<const uint32_t>,
+              GetContributingSources,
+              (),
+              (const, override));
   MOCK_METHOD(void, SetData, (rtc::ArrayView<const uint8_t>), (override));
   MOCK_METHOD(uint8_t, GetPayloadType, (), (const, override));
   MOCK_METHOD(uint32_t, GetSsrc, (), (const, override));
   MOCK_METHOD(uint32_t, GetTimestamp, (), (const, override));
   MOCK_METHOD(void, SetRTPTimestamp, (uint32_t), (override));
+  MOCK_METHOD(Direction, GetDirection, (), (const, override));
 };
 
 }  // namespace webrtc