media/engine/videoencodersoftwarefallbackwrapper.h

/*
 *  Copyright (c) 2016 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 MEDIA_ENGINE_VIDEOENCODERSOFTWAREFALLBACKWRAPPER_H_
#define MEDIA_ENGINE_VIDEOENCODERSOFTWAREFALLBACKWRAPPER_H_

#include <memory>
#include <string>
#include <vector>

#include "api/video_codecs/video_encoder.h"
#include "media/base/codec.h"

namespace webrtc {

// Class used to wrap external VideoEncoders to provide a fallback option on
// software encoding when a hardware encoder fails to encode a stream due to
// hardware restrictions, such as max resolution.
class VideoEncoderSoftwareFallbackWrapper : public VideoEncoder {
 public:
  VideoEncoderSoftwareFallbackWrapper(
      std::unique_ptr<webrtc::VideoEncoder> sw_encoder,
      std::unique_ptr<webrtc::VideoEncoder> hw_encoder);
  ~VideoEncoderSoftwareFallbackWrapper() override;

  int32_t InitEncode(const VideoCodec* codec_settings,
                     int32_t number_of_cores,
                     size_t max_payload_size) override;

  int32_t RegisterEncodeCompleteCallback(
      EncodedImageCallback* callback) override;

  int32_t Release() override;
  int32_t Encode(const VideoFrame& frame,
                 const CodecSpecificInfo* codec_specific_info,
                 const std::vector<FrameType>* frame_types) override;
  int32_t SetChannelParameters(uint32_t packet_loss, int64_t rtt) override;
  int32_t SetRateAllocation(const VideoBitrateAllocation& bitrate_allocation,
                            uint32_t framerate) override;
  bool SupportsNativeHandle() const override;
  ScalingSettings GetScalingSettings() const override;
  const char *ImplementationName() const override;

 private:
  bool InitFallbackEncoder();

  // If |forced_fallback_possible_| is true:
  // The forced fallback is requested if the resolution is less than or equal to
  // |max_pixels_|. The resolution is allowed to be scaled down to
  // |min_pixels_|.
  class ForcedFallbackParams {
   public:
    bool IsValid(const VideoCodec& codec) const {
      return codec.width * codec.height <= max_pixels_;
    }

    bool active_ = false;
    int min_pixels_ = 320 * 180;
    int max_pixels_ = 320 * 240;
  };

  bool TryInitForcedFallbackEncoder();
  bool TryReInitForcedFallbackEncoder();
  void ValidateSettingsForForcedFallback();
  bool IsForcedFallbackActive() const;
  void MaybeModifyCodecForFallback();

  // Settings used in the last InitEncode call and used if a dynamic fallback to
  // software is required.
  VideoCodec codec_settings_;
  int32_t number_of_cores_;
  size_t max_payload_size_;

  // The last bitrate/framerate set, and a flag for noting they are set.
  bool rates_set_;
  VideoBitrateAllocation bitrate_allocation_;
  uint32_t framerate_;

  // The last channel parameters set, and a flag for noting they are set.
  bool channel_parameters_set_;
  uint32_t packet_loss_;
  int64_t rtt_;

  bool use_fallback_encoder_;
  const std::unique_ptr<webrtc::VideoEncoder> encoder_;

  const std::unique_ptr<webrtc::VideoEncoder> fallback_encoder_;
  EncodedImageCallback* callback_;

  bool forced_fallback_possible_;
  ForcedFallbackParams forced_fallback_;
};

}  // namespace webrtc

#endif  // MEDIA_ENGINE_VIDEOENCODERSOFTWAREFALLBACKWRAPPER_H_