diff --git a/api/BUILD.gn b/api/BUILD.gn
index 517a0db0a0..b48247ce0f 100644
--- a/api/BUILD.gn
+++ b/api/BUILD.gn
@@ -162,6 +162,7 @@ rtc_library("libjingle_peerconnection_api") {
     ":audio_options_api",
     ":callfactory_api",
     ":fec_controller_api",
+    ":frame_transformer_interface",
     ":libjingle_logging_api",
     ":media_stream_interface",
     ":network_state_predictor_api",
@@ -213,6 +214,16 @@ rtc_library("libjingle_peerconnection_api") {
   ]
 }
 
+rtc_source_set("frame_transformer_interface") {
+  visibility = [ "*" ]
+  sources = [ "frame_transformer_interface.h" ]
+  deps = [
+    ":scoped_refptr",
+    "../rtc_base:refcount",
+    "video:encoded_frame",
+  ]
+}
+
 rtc_library("rtc_error") {
   visibility = [ "*" ]
   sources = [
diff --git a/api/DEPS b/api/DEPS
index ef9db30804..1e92b12281 100644
--- a/api/DEPS
+++ b/api/DEPS
@@ -90,6 +90,10 @@ specific_include_rules = {
     "+modules/include/module_fec_types.h",
   ],
 
+  "frame_transformer_interface\.h": [
+    "+rtc_base/ref_count.h",
+  ],
+
   "ice_transport_interface\.h": [
     "+rtc_base/ref_count.h",
   ],
diff --git a/api/frame_transformer_interface.h b/api/frame_transformer_interface.h
new file mode 100644
index 0000000000..666a791f91
--- /dev/null
+++ b/api/frame_transformer_interface.h
@@ -0,0 +1,58 @@
+/*
+ *  Copyright 2020 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_FRAME_TRANSFORMER_INTERFACE_H_
+#define API_FRAME_TRANSFORMER_INTERFACE_H_
+
+#include <memory>
+#include <vector>
+
+#include "api/scoped_refptr.h"
+#include "api/video/encoded_frame.h"
+#include "rtc_base/ref_count.h"
+
+namespace webrtc {
+
+// Objects implement this interface to be notified with the transformed frame.
+class TransformedFrameCallback : public rtc::RefCountInterface {
+ public:
+  virtual void OnTransformedFrame(
+      std::unique_ptr<video_coding::EncodedFrame> transformed_frame) = 0;
+
+ protected:
+  ~TransformedFrameCallback() override = default;
+};
+
+// Transformes encoded frames. The transformed frame is sent in a callback using
+// the TransformedFrameCallback interface (see below).
+class FrameTransformerInterface : public rtc::RefCountInterface {
+ public:
+  // Transforms |frame| using the implementing class' processing logic.
+  // |additional_data| holds data that is needed in the frame transformation
+  // logic, but is not included in |frame|; for example, when the transform
+  // function is used for encrypting/decrypting the frame, the additional data
+  // holds the serialized generic frame descriptor extension calculated in
+  // webrtc::RtpDescriptorAuthentication, needed in the encryption/decryption
+  // algorithms.
+  virtual void TransformFrame(std::unique_ptr<video_coding::EncodedFrame> frame,
+                              std::vector<uint8_t> additional_data,
+                              uint32_t ssrc) = 0;
+
+  virtual void RegisterTransformedFrameCallback(
+      rtc::scoped_refptr<TransformedFrameCallback>) = 0;
+  virtual void UnregisterTransformedFrameCallback() = 0;
+
+ protected:
+  ~FrameTransformerInterface() override = default;
+};
+
+}  // namespace webrtc
+
+#endif  // API_FRAME_TRANSFORMER_INTERFACE_H_