text: /*
   *  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 {
  
  // Owns the frame payload data.
  class TransformableFrameInterface {
   public:
    virtual ~TransformableFrameInterface() = default;
  
    // Returns the frame payload data. The data is valid until the next non-const
    // method call.
    virtual rtc::ArrayView<const uint8_t> GetData() const = 0;
  
    // Copies |data| into the owned frame payload data.
    virtual void SetData(rtc::ArrayView<const uint8_t> data) = 0;
  
    virtual uint32_t GetTimestamp() const = 0;
    virtual uint32_t GetSsrc() const = 0;
  };
  
  class TransformableVideoFrameInterface : public TransformableFrameInterface {
   public:
    virtual ~TransformableVideoFrameInterface() = default;
    virtual bool IsKeyFrame() const = 0;
  
    // Returns data needed in the frame transformation logic; for example,
    // when the transformation applied to the frame is encryption/decryption, the
    // additional data holds the serialized generic frame descriptor extension
    // calculated in webrtc::RtpDescriptorAuthentication.
    // TODO(bugs.webrtc.org/11380) remove from interface once
    // webrtc::RtpDescriptorAuthentication is exposed in api/.
    virtual std::vector<uint8_t> GetAdditionalData() const = 0;
  };
  
  // Extends the TransformableFrameInterface to expose audio-specific information.
  class TransformableAudioFrameInterface : public TransformableFrameInterface {
   public:
    virtual ~TransformableAudioFrameInterface() = default;
  
    // Exposes the frame header, enabling the interface clients to use the
    // information in the header as needed, for example to compile the list of
    // csrcs.
    virtual const RTPHeader& GetHeader() const = 0;
  };
  
  // Objects implement this interface to be notified with the transformed frame.
  class TransformedFrameCallback : public rtc::RefCountInterface {
   public:
    // TODO(bugs.webrtc.org/11380) remove after updating downstream dependencies
    // to use new OnTransformedFrame signature.
    virtual void OnTransformedFrame(
        std::unique_ptr<video_coding::EncodedFrame> transformed_frame) {}
    // TODO(bugs.webrtc.org/11380) make pure virtual after updating usage
    // downstream.
    virtual void OnTransformedFrame(
        std::unique_ptr<TransformableFrameInterface> transformed_frame) {}
  
   protected:
    ~TransformedFrameCallback() override = default;
  };
  
  // Transforms encoded frames. The transformed frame is sent in a callback using
  // the TransformedFrameCallback interface (see above).
  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.
    // TODO(bugs.webrtc.org/11380) remove after updating downstream dependencies
    // to use new OnTransformedFrame() signature.
    virtual void TransformFrame(std::unique_ptr<video_coding::EncodedFrame> frame,
                                std::vector<uint8_t> additional_data,
                                uint32_t ssrc) {}
  
    // Transforms |frame| using the implementing class' processing logic.
    // TODO(bugs.webrtc.org/11380) make pure virtual after updating usage
    // downstream.
    virtual void Transform(
        std::unique_ptr<TransformableFrameInterface> transformable_frame) {}
  
    virtual void RegisterTransformedFrameCallback(
        rtc::scoped_refptr<TransformedFrameCallback>) {}
    virtual void RegisterTransformedFrameSinkCallback(
        rtc::scoped_refptr<TransformedFrameCallback>,
        uint32_t ssrc) {}
    virtual void UnregisterTransformedFrameCallback() {}
    virtual void UnregisterTransformedFrameSinkCallback(uint32_t ssrc) {}
  
   protected:
    ~FrameTransformerInterface() override = default;
  };
  
  }  // namespace webrtc
  
  #endif  // API_FRAME_TRANSFORMER_INTERFACE_H_
  